The predominance of quarter-power scaling in biology

Authors


†Author to whom correspondence should be sent. E-mail: van@santafe.edu

Summary

  • 1Recent studies have resurrected the debate over the value for the allometric scaling exponent that relates whole-organism metabolic rate to body size. Is it 3/4 or 2/3? This question has been raised before and resolved in favour of 3/4. Like previous ones, recent claims for a value of 2/3 are based almost entirely on basal metabolic rate (BMR) in mammals.
  • 2Here we compile and analyse a new, larger data set for mammalian BMR. We show that interspecific variation in BMR, as well as field metabolic rates of mammals, and basal or standard metabolic rates for many other organisms, including vertebrates, invertebrates, protists and plants, all scale with exponents whose confidence intervals include 3/4 and exclude 2/3. Our analysis of maximal metabolic rate gives a slope that is greater than and confidence intervals that exclude both 3/4 and 2/3.
  • 3Additionally, numerous other physiological rates that are closely tied to metabolism in a wide variety of organisms, including heart and respiratory rates in mammals, scale as M−1/4.
  • 4The fact that quarter-power allometric scaling is so pervasive in biology suggests that different allometric relations have a common, mechanistic origin and provides an empirical basis for theoretical models that derive these scaling exponents.

Introduction

Many fundamental characteristics of organisms scale with body size as power laws of the form:

Y  =  Y0Mb,(eqn 1)

where Y is some characteristic such as metabolic rate, stride length or life span, Y0 is a normalization constant, M is body mass and b is the allometric scaling exponent. A longstanding puzzle in biology is why the exponent b is usually some simple multiple of 1/4 rather than a multiple of 1/3, as would be expected from Euclidean scaling.

Renewed interest in allometry is due at least in part to recent theories that purport to explain the quarter-power scaling (West, Brown & Enquist 1997, 1999a; Banavar, Maritan & Rinaldo 1999; Banavar et al. 2002). These theories derive the scaling for metabolic rate based on the designs of resource distribution networks, such as animal and plant vascular systems. In particular, the model of West et al. assumes that these networks have three properties: (1) they branch hierarchically to supply all parts of three dimensional organisms; (2) they have terminal units, such as capillaries or petioles, that do not vary with body size; and (3) natural selection has optimized hydrodynamic flow through the network so that the work required to distribute resources has been minimized. This model predicts many other characteristics of plant and animal circulatory systems, including dimensions of vessels, total volume of fluid, rates of flow and delivery times. This model has been extended to explain the quarter-power scaling of many biological traits, including mitochondrial densities (West, Woodruff & Brown 2002), ontogenetic growth rates (West, Brown & Enquist 2001), the partitioning and allocation of production between plant organs such as roots, stems, leaves, and reproductive structures (Enquist & Niklas 2002; Niklas & Enquist 2002), times of life-history events (Gillooly et al. 2002; Savage et al. 2004), and population growth rates (Savage et al. 2004).

Ever since the seminal studies of Kleiber (1932) and Brody et al. (1934, 1945), some biologists have questioned whether the exponent for whole-organism metabolic rate really is 3/4 or whether it might be 2/3 as expected from Euclidean geometric scaling (Heusner 1982a,b, 1987, 1991; Kooijman 2000; Dodds, Rothman & Weitz 2001; White & Seymour 2003). These questions have focused on metabolic rate because it is such a fundamental characteristic for all organisms. It is the rate at which energy and materials are transformed within organisms and exchanged with the environment.

In the present study, we evaluate the evidence for the scaling exponents for basal metabolic rate (BMR) and other traits. We analyse three kinds of data. First, we compile and analyse a new comprehensive data set for the basal metabolic rate of mammals. Second, we present analyses of field and maximal metabolic rates for mammals, because these rates are more relevant to the normal function of free-living mammals than BMR, and we present reanalyses of data for mammalian heart and respiratory rates. Third, we perform meta-analyses (i.e. we calculate the mean and standard error) of scaling exponents reported in the literature for other biological rates and times, some of which can be measured more accurately than BMR. Finally, we identify problems with recent studies that have claimed that BMR of mammals scales as M2/3(at least over a limited range of M) (Dodds et al. 2001; White & Seymour 2003). We conclude that the evidence supports the pervasiveness of quarter-power allometric scaling in biology and, by extension, the models of West et al. (1997, 1999a).

Historical perspective

The idea that power laws characterize size-related variation is old and well established in biology. Rubner (1883) originally observed that metabolic rate depended on organismal body size and proposed that the relationship followed from a surface-area rule (see also Bergman 1847). In the 1920s Julian Huxley investigated the body size dependence of ontogenetic growth and other biological attributes and coined the term ‘allometric equation’ for equation 1 (Huxley 1932; see also Thompson 1942). In the 1930s, Brody (1934, 1945) and Kleiber (1932) independently measured the whole-organism metabolic rates of diverse kinds of birds and mammals and fitted the data with allometric equations. Their results were slightly different: Brody obtained a value of 0·73, whereas Kleiber concluded the exponent was exactly 3/4. Both investigators were surprised that the value was different from 2/3, because they expected that metabolic rate in endotherms would vary with heat dissipation and therefore scale with body surface area, as hypothesized by Rubner. Explaining the observed exponents established a puzzle that has challenged biologists ever since.

Subsequent studies have given similar results. In a major monograph, Hemmingsen (1960) compiled data for endothermic birds and mammals, ectothermic vertebrates and invertebrates, and unicellular prokaryotes and eukaryotes. The fitted data for each group had allometric exponents of b ≈ 3/4. Extensive research on allometry in the 1970s and early 1980s was synthesized in four influential books by Peters (1983), McMahon & Bonner (1983), Calder (1984) and Schmidt-Nielsen (1984). These volumes reviewed the empirical evidence and found that it overwhelmingly supported quarter-power scaling for BMR and numerous other attributes of organismal form, function, physiology and life history. Peters (1983) remarks, ‘one cannot but wonder why the power formula, in general, and the mass exponents of 3/4, 1/4, and –1/4, in particular, are so effective in describing biological phenomenon.’Calder (1984) claims, ‘Despite shortcomings and criticisms [including the lack of a theoretical model], empirically most of the scaling does seem to fit M1/4 scaling …’. Schmidt-Nielsen (1984) declares that, ‘It has been widely accepted that the slope of the metabolic regression line for mammals is 0·75 or very close to it, and most definitely not 0·67 (as far as the “surface rule” would suggest)’, and that ‘… it is overwhelmingly certain that the exponent differs from 0·67 …’.

As suggested by the last quote, empirical studies forced scientists to conclude that biological allometry does not reflect simple geometric scaling. Not only does whole-organism metabolism scale as M3/4, but mass-specific metabolic rate and most other biological rates scale as M−1/4(e.g. heart and respiratory rates, stride frequencies) and most biological times scale as M1/4(e.g. life spans, times to first reproduction, muscle twitch contraction times) (Lindstedt & Calder 1981).

So compelling was the empirical evidence for quarter-power scaling that several mechanistic theories were developed to explain it. None of these, however, were sufficiently general to account for the ubiquity of quarter-power scaling across diverse kinds of organisms and environments. McMahon proposed a theory of elastic similarity based on biomechanical adaptations to gravitational forces (McMahon 1973, 1975). While his arguments might apply to the bones of mammals or the trunks of trees, it is doubtful that they are applicable to aquatic or unicellular organisms. Blum (1977) suggested that quarter powers could be attributed to a fourth dimension, which he identified as time. He did not, however, present an explicit, testable model. Patterson (1992) developed a model based on diffusion of respiratory gases across boundary layers in aquatic organisms. Its application to terrestrial organisms has not been attempted and would be problematic. Barenblatt & Monin (1983) proposed that quarter-power scaling might reflect the fractal-like nature of biology, thereby anticipating West et al. (1997), but again, they did not provide a mechanistic, dynamical model.

However, quarter-power scaling has not been universally accepted. For a decade, beginning in the 1980s, Heusner presented analyses and arguments that the exponent for mammalian BMR was 2/3 rather than 3/4 (Heusner 1982a, 1982b). Heusner's criticisms were answered by Bartels (1982) and Feldman & McMahon (1983) (see also Schmidt-Nielsen 1984, pp. 60–62). As a consequence, the debate subsided, the ubiquity of quarter powers was widely accepted, and there was relatively little research in allometry until the late 1990s when a series of theoretical papers appeared (West et al. 1997, 1999a, 2001, 2002; Enquist, Brown & West 1998; Banavar et al. 1999, 2002; West, Brown & Enquist 1999b; Enquist & Niklas 2001, 2002; Niklas & Enquist 2001, 2002; Gillooly et al. 2002; Savage et al. 2004).

West, Brown, Enquist and their collaborators developed detailed models for the geometry and hydrodynamics of hierarchically branched mammal and plant vascular systems that accurately predicted empirically determined allometric scaling relations for many structural and functional traits (West et al. 1997, 1999a). Extensions of these models predict the allometries of ontogenetic growth trajectories (West et al. 2001), population growth rates and other life-history attributes (Savage et al. 2004), variability in biomass, abundance and productivity of plant communities (Enquist et al. 1998; West et al. 1999b; Enquist & Niklas 2001, 2002; Niklas & Enquist 2001, 2002; Belgrano et al. 2002; Niklas, Midgely & Enquist 2003), and metabolic rates at cellular, organelle and molecular levels (West et al. 2002). The theory of West, Brown & Enquist and its extensions quantitatively explain and predict a large body of empirical measurements taken across broad scales for a variety of biological phenomena; this includes not only quarter-power allometric exponents but, just as importantly, details of hierarchical branching and hydrodynamic flow.

Analyses: basal metabolic rate of mammals

The debate as to whether BMR scales as M3/4 or M2/3 has recently been resurrected. Dodds et al. (2001) reanalysed Heusner's (1991) and some other existing data sets using different statistical methods and concluded that the 2/3 exponent for BMR in mammals and birds cannot be statistically rejected and that over a limited range it is, in fact, favoured. White & Seymour (2003) compiled and analysed a large data set on BMR in mammals and reached similar conclusions. We argue here that there are two reasons why these studies are inadequate to address the generality of quarter- vs third-power allometric scaling. First, each study uses questionable, ad hoc methods. Second, these studies focus exclusively on the BMR of mammals and birds and ignore the large number of published empirical scaling relations for different taxonomic groups and for other traits, many of which are easier to measure accurately and are closely tied to metabolism.

question 1: how does mammalian bmr scale?

Much of the interest in allometry has focused on mammalian BMR. There have been many studies, which have generated a large quantity of data, representing measurements for hundreds of species. The vast majority of these studies were designed to address specific questions about the physiology of mammals in particular environments or taxonomic groups. They were not designed to address the question of allometric scaling of BMR across all mammals. Consequently, these large compilations of data represent an opportunistic collection that may not be representative of the Class Mammalia. In addition, these data seriously violate assumptions of the parametric statistics used to fit regression lines and calculate allometric exponents (Sokal & Rohlf 1981). Two problems are especially serious. First, the vast majority of data are for small mammals (i.e. M < 1 kg) (see Fig. 1). Unless some correction is made for this imbalance, the calculated regression statistics (slope, intercept and confidence intervals) will be biased. Second, because BMR databases contain multiple values for species in certain genera or families and few or no values for other genera or families, the data are neither independent nor representative. For example, measurements for rodents are abundant and thus contribute an undue influence on the scaling of BMR.

Figure 1.

Plot of the combined mammalian data sets of Hart (1971), Heusner (1991), Lovegrove (2000, 2003) and White & Seymour (2003), which yields a total of 626 species data points. The numerous bars are the raw data. The regression line is fitted to the average of the logarithms for every 0·1 log unit interval of mass, represented by the squares. Note that the slope is very close to 3/4, b = 0·737 (P < 0·0001, n = 52, 95% C.I. 0·711, 0·762), and the 95% C.I. exclude 2/3.

Methods

We compiled data on mammalian BMR from the large data sets used in the previous studies of Hart (1971), Heusner (1991), Lovegrove (2000, 2003) and White & Seymour (2003). In compiling this data set we found several discrepancies between the data sets of Heusner (1991), Lovegrove (2000, 2003) and White & Seymour (2003), e.g. values that differed by an order of magnitude in mass and BMR for the same species taken from the same study. These discrepancies were the result of incorrect or changed scientific names in Heusner (1991), apparent transcription and conversion errors in Lovegrove (2000, 2003), and misplaced decimal points (e.g. the reported mass for Ursus ursinus) and the shifting of rows in the BMR column for the Order Chiroptera in the appendix of White & Seymour (2003). When different data sets contained significantly different values for the same species from the same study, we referred to the original source and used the values reported there. The original sources that were consulted are given in the References section and are listed by the relevant species data in Appendix 1. Moreover, there were many species whose scientific names have changed over the period spanned by these data sets, so the list was checked extensively in order to standardize the scientific names. All names were standardized according to Wilson & Reeder (1993), and consequently, some scientific names given here differ from the ones given in the original studies. We then eliminated duplicate data, i.e. values for the same species taken from the same study that appear in multiple data sets, keeping only one datum for each of these cases. Often, for the duplicate data there were slight differences between values reported in Heusner (1991), Lovegrove (2000, 2003) and White & Seymour (2003) due either to different methods of averaging or to differing procedures for rounding before and after conversions. In an attempt to further standardize the data, we took the datum from the most recent compilation when there was this sort of discrepancy.

Table Appendix 1. 
OrderFamilySpeciesMass (g)BMR (W)Species avg. mass (g)Species avg. BMR (W)References
ArtiodactylaAntilocapridaeAntilocapra americana32 00049·98434 779·350·973Lovegrove (2000)
ArtiodactylaAntilocapridaeAntilocapra americana37 80051·981  White & Seymour (2003)
ArtiodactylaBovidaeBos taurus347 000306·770347 000·0306·770Heusner (1991)
ArtiodactylaBovidaeCephalophus monticola4 20010·0754 200·010·075Lovegrove (2000)
ArtiodactylaBovidaeConnochaetes taurinus196 500230·073196 500·0230·073White & Seymour (2003), Rogerson (1968)
ArtiodactylaBovidaeKobus ellipsiprymnus100 000148·949100 000·0148·949Lovegrove (2000)
ArtiodactylaBovidaeMadoqua kirkii4 29011·9664 290·011·966Lovegrove (2000)
ArtiodactylaBovidaeOreamnos americanus32 00046·41432 000·046·414Lovegrove (2000)
ArtiodactylaBovidaeOvis canadensis65 000123·28767 030·8114·674Lovegrove (2000)
ArtiodactylaBovidaeOvis canadensis69 125106·663  White & Seymour (2003)
ArtiodactylaBovidaeRaphicerus campestris9 60020·6199 600·020·619Lovegrove (2000)
ArtiodactylaBovidaeTaurotragus oryx133 300180·150141 403·7190·209Heusner (1991)
ArtiodactylaBovidaeTaurotragus oryx150 000200·830  Lovegrove (2000)
ArtiodactylaCamelidaeCamelus dromedarius407 000224·779407 000·0224·779Lovegrove (2000)
ArtiodactylaCamelidaeLama glama115 000148·940115 000·0148·940Heusner (1991)
ArtiodactylaCanidaeCervus elaphus67 000112·43067 000·0112·430Heusner (1991)
ArtiodactylaCervidaeAlces alces325 000286·847325 000·0286·847White & Seymour (2003)
ArtiodactylaCervidaeCapreolus capreolus21 50046·34721 500·046·347Weiner (1977)
ArtiodactylaCervidaeOdocoileus virginianus58 588142·86361 862·5123·447White & Seymour (2003)
ArtiodactylaCervidaeOdocoileus virginianus65 320106·670  Heusner (1991)
ArtiodactylaCervidaeRangifer tarandus85 000119·66085 000·0119·660Heusner (1991)
ArtiodactylaSuidaeSus scrofa135 000104·150135 000·0104·150Heusner (1991)
ArtiodactylaTayassuidaePecari tajacu20 50033·16520 500·033·165White & Seymour (2003)
ArtiodactylaTragulidaeTragulus javanicus1 6134·9001 615·54·883Heusner (1991)
ArtiodactylaTragulidaeTragulus javanicus1 6184·865  Lovegrove (2000)
CarnivoraCanidaeAlopex lagopus3 6007·6653 600·07·665White & Seymour (2003)
CarnivoraCanidaeCanis latrans10 00014·99010 148·919·423White & Seymour (2003)
CarnivoraCanidaeCanis latrans10 30025·167  Lovegrove (2000)
CarnivoraCanidaeCanis mesomelas7 72021·5337 720·021·533White & Seymour (2003)
CarnivoraCanidaeCerdocyon thous5 4448·5025 444·08·502White & Seymour (2003)
CarnivoraCanidaeLycaon pictus8 75033·0108 750·033·010Heusner (1991)
CarnivoraCanidaeVulpes velox1 7694·9481 769·04·948White & Seymour (2003)
CarnivoraCanidaeVulpes vulpes4 44013·6234 580·313·731White & Seymour (2003)
CarnivoraCanidaeVulpes vulpes4 72513·841  White & Seymour (2003)
CarnivoraCanidaeVulpes zerda1 1062·2301 159·22·693Heusner (1991)
CarnivoraCanidaeVulpes zerda1 2153·252  White & Seymour (2003)
CarnivoraFelidaeAcinonyx jubatus37 90050·10738 446·161·770White & Seymour (2003)
CarnivoraFelidaeAcinonyx jubatus39 00076·148  Lovegrove (2000)
CarnivoraFelidaeFelis concolor37 20049·32637 200·049·326White & Seymour (2003)
CarnivoraFelidaeHerpailurus yaguarondi8 4009·6908 400·09·690White & Seymour (2003)
CarnivoraFelidaeLeopardus pardalis10 50017·43910 500·017·439White & Seymour (2003)
CarnivoraFelidaeLeopardus wiedii3 6005·2273 600·05·227White & Seymour (2003)
CarnivoraFelidaeLeptailurus serval1 0121·4401 012·01·440Lovegrove (2000)
CarnivoraFelidaeLynx rufus9 40023·5429 400·023·542White & Seymour (2003)
CarnivoraFelidaePanthera leo98 00094·58098 000·094·580White & Seymour (2003)
CarnivoraFelidaePanthera onca50 40062·41950 400·062·419White & Seymour (2003)
CarnivoraFelidaePanthera tigris137 900133·859137 900·0133·859White & Seymour (2003)
CarnivoraHerpestidaeGalerella sanguinea5002·120519·62·202Kamau et al. (1979)
CarnivoraHerpestidaeGalerella sanguinea5402·287  White & Seymour (2003)
CarnivoraHerpestidaeHerpestes javanicus6112·248611·02·248White & Seymour (2003)
CarnivoraHerpestidaeSuricata suricatta8501·729850·01·729White & Seymour (2003)
CarnivoraHyaenidaeHyaena hyaena34 30031·95434 300·031·954White & Seymour (2003)
CarnivoraHyaenidaeProteles cristatus7 71010·9257 902·611·563Lovegrove (2000)
CarnivoraHyaenidaeProteles cristatus8 10012·239  White & Seymour (2003)
CarnivoraMustelidaeEira barbara2 9506·8112 950·06·811White & Seymour (2003)
CarnivoraMustelidaeEnhydra lutris18 00067·27826 832·898·479Lovegrove (2000)
CarnivoraMustelidaeEnhydra lutris40 000144·150  Heusner (1991)
CarnivoraMustelidaeGulo gulo12 70031·76512 700·031·765White & Seymour (2003)
CarnivoraMustelidaeLutra lutra10 00025·10410 000·025·104White & Seymour (2003)
CarnivoraMustelidaeMartes americana9003·319966·53·579White & Seymour (2003)
CarnivoraMustelidaeMartes americana1 0383·860  Heusner (1991)
CarnivoraMustelidaeMartes martes9204·000920·04·000White & Seymour (2003)
CarnivoraMustelidaeMeles meles11 05016·64711 050·016·647White & Seymour (2003)
CarnivoraMustelidaeMustela erminea750·930125·51·276Heusner (1991)
CarnivoraMustelidaeMustela erminea2101·750  Heusner (1991)
CarnivoraMustelidaeMustela frenata2251·344225·01·344White & Seymour (2003)
CarnivoraMustelidaeMustela vison6602·722660·02·722White & Seymour (2003)
CarnivoraMustelidaeSpilogale putorius6241·674624·01·674White & Seymour (2003)
CarnivoraMustelidaeTaxidea taxus9 00015·0629 000·015·062White & Seymour (2003)
CarnivoraPhocidaePhoca fasciata54 000118·59054 000·0118·590Heusner (1991)
CarnivoraPhocidaePhoca groenlandica150 000168·930150 000·0168·930Heusner (1991)
CarnivoraPhocidaePhoca vitulina27 40073·29027 400·073·290Heusner (1991)
CarnivoraProcyonidaeAilurus fulgens5 7404·8985 740·04·898White & Seymour (2003)
CarnivoraProcyonidaeBassariscus sumichrasti1 2803·5371 280·03·537White & Seymour (2003)
CarnivoraProcyonidaeNasua narica3 6706·7333 670·06·733White & Seymour (2003)
CarnivoraProcyonidaeNasua nasua3 8505·6493 924·35·591Lovegrove (2000)
CarnivoraProcyonidaeNasua nasua4 0005·534  White & Seymour (2003)
CarnivoraProcyonidaePotos flavus2 2154·1772 318·04·294Lovegrove (2000)
CarnivoraProcyonidaePotos flavus2 3434·441  White & Seymour (2003)
CarnivoraProcyonidaePotos flavus2 4004·270  Heusner (1991)
CarnivoraProcyonidaeProcyon cancrivorus1 1602·5881 160·02·588White & Seymour (2003)
CarnivoraProcyonidaeProcyon lotor4 62012·1914 842·210·428Lovegrove (2000)
CarnivoraProcyonidaeProcyon lotor5 0758·920  White & Seymour (2003)
CarnivoraUrsidaeMelursus ursinus66 95747·06466 957·047·064McNab (1992)
CarnivoraViverridaeArctictis binturong14 28012·74714 280·012·747White & Seymour (2003)
CarnivoraViverridaeArctogalidia trivirgata2 0103·0852 010·03·085White & Seymour (2003)
CarnivoraViverridaeFossa fossana2 2605·0902 260·05·090Heusner (1991)
CarnivoraViverridaeGenetta tigrina1 6984·1671 699·04·189White & Seymour (2003)
CarnivoraViverridaeGenetta tigrina1 7004·210  Heusner (1991)
CarnivoraViverridaeNandinia binotata4 2704·8144 270·05·565White & Seymour (2003)
CarnivoraViverridaeNandinia binotata4 2706·432  Lovegrove (2000)
CarnivoraViverridaeParadoxurus hermaphroditus3 1607·6653 282·65·534White & Seymour (2003)
CarnivoraViverridaeParadoxurus hermaphroditus3 4103·995  Lovegrove (2000)
ChiropteraEmballonuridaePeropteryx macrotis50·0655·00·065White & Seymour (2003)
ChiropteraEmballonuridaeSaccopteryx bilineata7·80·0817·80·081Lovegrove (2000)
ChiropteraHipposideridaeRhinonycteris aurantius8·270·0908·30·090Baudinette et al. (2000)
ChiropteraMegadermatidaeMacroderma gigas107·20·526126·00·639Baudinette et al. (2000)
ChiropteraMegadermatidaeMacroderma gigas1480·776  McNab (1969)
ChiropteraMolossidaeEumops perotis560·22256·00·222White & Seymour (2003)
ChiropteraMolossidaeMolossus molossus15·60·12615·60·126White & Seymour (2003)
ChiropteraMolossidaeNyctinomops laticaudatus140·06214·00·062Lovegrove (2000)
ChiropteraMolossidaeTadarida brasiliensis10·40·12013·30·117Heusner (1991)
ChiropteraMolossidaeTadarida brasiliensis16·90·113  White & Seymour (2003)
ChiropteraMormoopidaeMormoops blainvillii8·60·0458·60·045White & Seymour (2003)
ChiropteraMormoopidaeMormoops megalophylla16·50·13616·50·136White & Seymour (2003)
ChiropteraMormoopidaePteronotus davyi9·40·0859·40·085Lovegrove (2000)
ChiropteraMormoopidaePteronotus parnellii19·20·17119·20·171Lovegrove (2000)
ChiropteraMormoopidaePteronotus personatus140·12814·00·128Lovegrove (2000)
ChiropteraMormoopidaePteronotus quadridens4·90·0344·90·034White & Seymour (2003)
ChiropteraNatalidaeNatalus tumidirostris5·40·0465·40·046White & Seymour (2003)
ChiropteraNoctilionidaeNoctilio albiventris270·17627·00·176McNab (1969)
ChiropteraNoctilionidaeNoctilio leporinus610·40061·00·400McNab (1969)
ChiropteraPhyllostomidaeAnoura caudifera11·50·23811·50·238McNab (1969)
ChiropteraPhyllostomidaeArtibeus concolor19·70·22219·70·222McNab (1969)
ChiropteraPhyllostomidaeArtibeus fimbriatus63·90·43563·90·435White & Seymour (2003)
ChiropteraPhyllostomidaeArtibeus jamaicensis45·20·42846·10·359McNab (1969)
ChiropteraPhyllostomidaeArtibeus jamaicensis470·300  Heusner (1991)
ChiropteraPhyllostomidaeArtibeus lituratus70·10·60270·10·602McNab (1969)
ChiropteraPhyllostomidaeCarollia perspicillata14·90·24014·90·240McNab (1969)
ChiropteraPhyllostomidaeChiroderma doriae19·90·17319·90·173White & Seymour (2003)
ChiropteraPhyllostomidaeChrotopterus auritus96·10·78896·10·788McNab (1969)
ChiropteraPhyllostomidaeDesmodus rotundus29·40·19429·40·194McNab (1969)
ChiropteraPhyllostomidaeDiaemus youngi36·60·20836·60·208McNab (1969)
ChiropteraPhyllostomidaeDiphylla ecaudata27·80·21527·80·215McNab (1969)
ChiropteraPhyllostomidaeErophylla sezekorni16·10·09916·10·099White & Seymour (2003)
ChiropteraPhyllostomidaeGlossophaga soricina9·60·1649·60·164McNab (1969)
ChiropteraPhyllostomidaeLeptonycteris curasoae220·24522·00·245White & Seymour (2003)
ChiropteraPhyllostomidaeMacrotus californicus11·70·08211·70·082Lovegrove (2000)
ChiropteraPhyllostomidaeMonophyllus redmani8·70·0628·70·062White & Seymour (2003)
ChiropteraPhyllostomidaePhyllostomus discolor33·50·26733·50·267McNab (1969)
ChiropteraPhyllostomidaePhyllostomus elongatus35·60·21635·60·216White & Seymour (2003)
ChiropteraPhyllostomidaePhyllostomus hastatus84·20·55984·20·559McNab (1969)
ChiropteraPhyllostomidaePlatyrrhinus lineatus21·90·25021·90·250McNab (1969)
ChiropteraPhyllostomidaeRhinophylla fischerae9·50·0919·50·091Lovegrove (2000)
ChiropteraPhyllostomidaeRhinophylla pumilio9·50·1049·50·104McNab (1969)
ChiropteraPhyllostomidaeSturnira lilium210·19021·40·237Heusner (1991)
ChiropteraPhyllostomidaeSturnira lilium21·90·297  McNab (1969)
ChiropteraPhyllostomidaeSturnira tildae20·50·22320·50·223White & Seymour (2003)
ChiropteraPhyllostomidaeTonatia bidens27·40·30727·40·307McNab (1969)
ChiropteraPhyllostomidaeUroderma bilobatum16·20·17616·20·176McNab (1969)
ChiropteraPhyllostomidaeVampyressa pusilla8·80·1048·80·104White & Seymour (2003)
ChiropteraPteropodidaeCynopterus brachyotis370·26037·20·262Heusner (1991)
ChiropteraPteropodidaeCynopterus brachyotis37·40·265  White & Seymour (2003)
ChiropteraPteropodidaeDobsonia minor73·70·41580·10·504White & Seymour (2003)
ChiropteraPteropodidaeDobsonia minor870·612  Lovegrove (2000)
ChiropteraPteropodidaeDobsonia moluccensis241·40·971312·41·411White & Seymour (2003)
ChiropteraPteropodidaeDobsonia moluccensis404·32·052  White & Seymour (2003)
ChiropteraPteropodidaeDobsonia praedatrix179·50·795179·50·795White & Seymour (2003)
ChiropteraPteropodidaeEonycteris spelaea51·60·26851·60·268Lovegrove (2000)
ChiropteraPteropodidaeMacroglossus minimus15·90·10315·90·103White & Seymour (2003)
ChiropteraPteropodidaeMegaloglossus woermanni12·40·12112·40·121Lovegrove (2000)
ChiropteraPteropodidaeMelonycteris melanops53·30·24253·30·242White & Seymour (2003)
ChiropteraPteropodidaeNyctimene albiventer28·20·22529·50·185Lovegrove (2000)
ChiropteraPteropodidaeNyctimene albiventer30·90·152  White & Seymour (2003)
ChiropteraPteropodidaeNyctimene cyclotis40·40·36040·40·360White & Seymour (2003)
ChiropteraPteropodidaeNyctimene major13·60·11413·60·114White & Seymour (2003)
ChiropteraPteropodidaeParanyctimene raptor21·30·17022·40·152Heusner (1991)
ChiropteraPteropodidaeParanyctimene raptor23·60·137  White & Seymour (2003)
ChiropteraPteropodidaePteropus giganteus562·21·622562·21·622White & Seymour (2003)
ChiropteraPteropodidaePteropus hypomelanus520·81·618520·81·618White & Seymour (2003)
ChiropteraPteropodidaePteropus poliocephalus5981·768598·01·768White & Seymour (2003)
ChiropteraPteropodidaePteropus pumilus194·20·705194·20·705White & Seymour (2003)
ChiropteraPteropodidaePteropus rodricensis254·50·753254·50·753White & Seymour (2003)
ChiropteraPteropodidaePteropus scapulatus3621·353362·01·353White & Seymour (2003)
ChiropteraPteropodidaePteropus vampyrus1024·34·4861024·34·486White & Seymour (2003)
ChiropteraPteropodidaeRousettus aegyptiacus1460·684146·00·684White & Seymour (2003)
ChiropteraPteropodidaeRousettus amplexicaudatus91·50·58291·50·582White & Seymour (2003)
ChiropteraPteropodidaeSyconycteris australis15·90·12216·70·152White & Seymour (2003)
ChiropteraPteropodidaeSyconycteris australis17·50·188  McNab (1969)
ChiropteraRhinolophidaeHipposideros galeritus8·50·0508·50·050Heusner (1991)
ChiropteraVespertilionidaeAntrozous pallidus220·10422·00·104Lovegrove (2000)
ChiropteraVespertilionidaeChalinolobus gouldii17·50·14117·50·141White & Seymour (2003)
ChiropteraVespertilionidaeEptesicus fuscus10·40·11613·30·113White & Seymour (2003)
ChiropteraVespertilionidaeEptesicus fuscus16·90·110  Heusner (1991)
ChiropteraVespertilionidaeHistiotus velatus11·20·08811·20·088White & Seymour (2003)
ChiropteraVespertilionidaeMiniopterus schreibersi10·910·14510·90·145Baudinette et al. (2000)
ChiropteraVespertilionidaeMyotis lucifugus5·20·0505·80·051White & Seymour (2003)
ChiropteraVespertilionidaeMyotis lucifugus6·50·052  Lovegrove (2000)
ChiropteraVespertilionidaeMyotis nigricans3·70·0273·70·027Lovegrove (2000)
ChiropteraVespertilionidaeMyotis velifer11·890·04011·90·040Heusner (1991)
ChiropteraVespertilionidaeMyotis vivesi250·19925·00·199Lovegrove (2000)
ChiropteraVespertilionidaeMyotis yumanensis50·0475·00·047Lovegrove (2000)
ChiropteraVespertilionidaeNyctophilus geoffroyi80·0628·00·062White & Seymour (2003)
ChiropteraVespertilionidaePlecotus auritus10·250·08210·20·082White & Seymour (2003)
DasyuromorphaCaluromyidaeCaluromys derbianus3291·255342·71·194White & Seymour (2003)
DasyuromorphaCaluromyidaeCaluromys derbianus3571·135  Lovegrove (2000)
DasyuromorphaDasyuridaeAntechinus flavipes46·50·25246·50·252White & Seymour (2003)
DasyuromorphaDasyuridaeAntechinus stuartii22·10·19025·00·189Heusner (1991)
DasyuromorphaDasyuridaeAntechinus stuartii28·20·189  White & Seymour (2003)
DasyuromorphaDasyuridaeAntechinus swainsonii66·90·35166·90·351White & Seymour (2003)
DasyuromorphaDasyuridaeDasycercus byrnei890·440100·00·439Heusner (1991)
DasyuromorphaDasyuridaeDasycercus byrnei91·70·400  White & Seymour (2003)
DasyuromorphaDasyuridaeDasycercus byrnei103·50·456  Lovegrove (2000)
DasyuromorphaDasyuridaeDasycercus byrnei118·20·462  Lovegrove (2003)
DasyuromorphaDasyuridaeDasycercus cristicauda860·24091·00·260Lovegrove (2003)
DasyuromorphaDasyuridaeDasycercus cristicauda88·80·260  Heusner (1991)
DasyuromorphaDasyuridaeDasycercus cristicauda890·258  Lovegrove (2000)
DasyuromorphaDasyuridaeDasycercus cristicauda1010·285  White & Seymour (2003)
DasyuromorphaDasyuridaeDasyurus geoffroii1 3002·8201 326·72·991Heusner (1991)
DasyuromorphaDasyuridaeDasyurus geoffroii1 3543·172  Lovegrove (2000)
DasyuromorphaDasyuridaeDasyurus hallucatus5581·356571·01·501White & Seymour (2003)
DasyuromorphaDasyuridaeDasyurus hallucatus584·41·663  Lovegrove (2003)
DasyuromorphaDasyuridaeDasyurus maculatus1 7823·0101 782·03·142Heusner (1991)
DasyuromorphaDasyuridaeDasyurus maculatus1 7823·281  White & Seymour (2003)
DasyuromorphaDasyuridaeDasyurus viverrinus909·92·310945·32·260Heusner (1991)
DasyuromorphaDasyuridaeDasyurus viverrinus9822·210  White & Seymour (2003)
DasyuromorphaDasyuridaeNingaui yvonnae11·60·08811·60·088White & Seymour (2003)
DasyuromorphaDasyuridaePhascogale tapoatafa1470·664153·70·694Lovegrove (2000)
DasyuromorphaDasyuridaePhascogale tapoatafa1570·710  White & Seymour (2003)
DasyuromorphaDasyuridaePhascogale tapoatafa157·20·710  Lovegrove (2003)
DasyuromorphaDasyuridaePlanigale gilesi8·90·0719·10·058Lovegrove (2000)
DasyuromorphaDasyuridaePlanigale gilesi9·10·039  White & Seymour (2003)
DasyuromorphaDasyuridaePlanigale gilesi9·40·070  Heusner (1991)
DasyuromorphaDasyuridaePlanigale ingrami7·10·0638·80·065White & Seymour (2003)
DasyuromorphaDasyuridaePlanigale ingrami10·80·067  White & Seymour (2003)
DasyuromorphaDasyuridaePlanigale maculata8·50·06010·60·067Heusner (1991)
DasyuromorphaDasyuridaePlanigale maculata13·10·074  Lovegrove (2000)
DasyuromorphaDasyuridaePlanigale tenuirostris7·10·0637·10·063White & Seymour (2003)
DasyuromorphaDasyuridaePseudantechinus macdonnellensis43·10·15243·10·152White & Seymour (2003)
DasyuromorphaDasyuridaeSarcophilus laniarius5 7757·3946 126·88·664White & Seymour (2003)
DasyuromorphaDasyuridaeSarcophilus laniarius6 50010·153  Lovegrove (2000)
DasyuromorphaDasyuridaeSminthopsis crassicaudata14·10·11016·00·121Heusner (1991)
DasyuromorphaDasyuridaeSminthopsis crassicaudata15·90·114  Lovegrove (2000)
DasyuromorphaDasyuridaeSminthopsis crassicaudata16·40·140  White & Seymour (2003)
DasyuromorphaDasyuridaeSminthopsis crassicaudata17·70·123  Lovegrove (2003)
DasyuromorphaDasyuridaeSminthopsis laniger24·20·13225·80·141White & Seymour (2003)
DasyuromorphaDasyuridaeSminthopsis laniger25·80·141  White & Seymour (2003)
DasyuromorphaDasyuridaeSminthopsis laniger27·40·150  Lovegrove (2003)
DasyuromorphaDasyuridaeSminthopsis macroura19·350·12620·60·128White & Seymour (2003)
DasyuromorphaDasyuridaeSminthopsis macroura220·131  Lovegrove (2000)
DasyuromorphaDasyuridaeSminthopsis murina12·90·11415·70·117Lovegrove (2000)
DasyuromorphaDasyuridaeSminthopsis murina190·120  White & Seymour (2003)
DasyuromorphaDidelphidaeChironectes minimus9352·549940·52·793White & Seymour (2003)
DasyuromorphaDidelphidaeChironectes minimus9463·061  Lovegrove (2000)
DasyuromorphaDidelphidaeDidelphis marsupialis1 1653·1851 244·33·310White & Seymour (2003)
DasyuromorphaDidelphidaeDidelphis marsupialis1 3293·440  Heusner (1991)
DasyuromorphaDidelphidaeDidelphis virginiana2 4884·6412 846·65·299White & Seymour (2003)
DasyuromorphaDidelphidaeDidelphis virginiana3 2576·050  Heusner (1991)
DasyuromorphaDidelphidaeLutreolina crassicaudata8122·265812·02·265White & Seymour (2003)
DasyuromorphaDidelphidaePhilander opossum7511·886751·01·886White & Seymour (2003)
DasyuromorphaMarmosidaeGracilinanus microtarsus130·10613·00·106White & Seymour (2003)
DasyuromorphaMarmosidaeMarmosa robinsoni1220·547122·00·547White & Seymour (2003)
DasyuromorphaMarmosidaeMetachirus nudicaudatus3361·144336·01·144White & Seymour (2003)
DasyuromorphaMarmosidaeMonodelphis brevicaudata75·50·31891·50·366White & Seymour (2003)
DasyuromorphaMarmosidaeMonodelphis brevicaudata1110·421  Lovegrove (2000)
DasyuromorphaMarmosidaeMonodelphis domestica1040·335104·00·335White & Seymour (2003)
DasyuromorphaMyrmecobiidaeMyrmecobius fasciatus4000·794438·20·907White & Seymour (2003)
DasyuromorphaMyrmecobiidaeMyrmecobius fasciatus4801·036  Lovegrove (2003)
DiprotodontiaAcrobatidaeAcrobates pygmaeus140·08414·00·084White & Seymour (2003)
DiprotodontiaBurramyidaeBurramys parvus44·30·20544·30·205White & Seymour (2003)
DiprotodontiaBurramyidaeCercartetus lepidus12·60·10512·60·105White & Seymour (2003)
DiprotodontiaBurramyidaeCercartetus nanus600·28864·80·311Lovegrove (2000)
DiprotodontiaBurramyidaeCercartetus nanus700·336  White & Seymour (2003)
DiprotodontiaMacropodidaeDendrolagus matschiei6 9607·9606 960·07·960White & Seymour (2003)
DiprotodontiaMacropodidaeLagorchestes conspicillatus2 6604·7492 660·04·749White & Seymour (2003)
DiprotodontiaMacropodidaeMacropus eugenii4 7967·7804 796·07·780Heusner (1991)
DiprotodontiaMacropodidaeMacropus robustus29 30031·71029 647·933·056White & Seymour (2003)
DiprotodontiaMacropodidaeMacropus robustus30 00034·460  Heusner (1991)
DiprotodontiaMacropodidaeMacropus rufus25 00030·13028 500·031·353Heusner (1991)
DiprotodontiaMacropodidaeMacropus rufus32 49032·625  White & Seymour (2003)
DiprotodontiaMacropodidaeSetonix brachyurus2 5104·5202 702·34·695Heusner (1991)
DiprotodontiaMacropodidaeSetonix brachyurus2 6744·654  White & Seymour (2003)
DiprotodontiaMacropodidaeSetonix brachyurus2 9404·920  Lovegrove (2000)
DiprotodontiaPetauridaeGymnobelideus leadbeateri1660·574166·00·574White & Seymour (2003)
DiprotodontiaPetauridaePetaurus breviceps1270·502129·30·517White & Seymour (2003)
DiprotodontiaPetauridaePetaurus breviceps128·10·500  Heusner (1991)
DiprotodontiaPetauridaePetaurus breviceps1300·522  Lovegrove (2000)
DiprotodontiaPetauridaePetaurus breviceps132·20·546  Lovegrove (2003)
DiprotodontiaPhalangeridaeSpilocuscus maculatus4 2506·1644 250·06·270Lovegrove (2000)
DiprotodontiaPhalangeridaeSpilocuscus maculatus4 2506·378  White & Seymour (2003)
DiprotodontiaPhalangeridaeTrichosurus vulpecula1 9823·5381 993·53·800Lovegrove (2000)
DiprotodontiaPhalangeridaeTrichosurus vulpecula2 0054·081  White & Seymour (2003)
DiprotodontiaPhascolarctidaePhascolarctos cinereus4 7005·7204 732·45·744Heusner (1991)
DiprotodontiaPhascolarctidaePhascolarctos cinereus4 7655·768  White & Seymour (2003)
DiprotodontiaPotoroidaeAepyprymnus rufescens2 8205·9782 820·05·978White & Seymour (2003)
DiprotodontiaPotoroidaeBettongia gaimardi1 3853·5781 385·03·578White & Seymour (2003)
DiprotodontiaPotoroidaeBettongia penicillata1 0183·1321 018·03·132White & Seymour (2003)
DiprotodontiaPotoroidaePotorous tridactylus9762·3231 045·52·556White & Seymour (2003)
DiprotodontiaPotoroidaePotorous tridactylus1 1202·812  Lovegrove (2000)
DiprotodontiaPseudocheiridaeCercartetus concinnus18·60·12518·60·125Lovegrove (2000)
DiprotodontiaPseudocheiridaePetauroides volans1 1403·1801 140·53·191Lovegrove (2000)
DiprotodontiaPseudocheiridaePetauroides volans1 1413·202  White & Seymour (2003)
DiprotodontiaPseudocheiridaePseudocheirus peregrinus8282·210859·32·270Heusner (1991)
DiprotodontiaPseudocheiridaePseudocheirus peregrinus8352·194  Lovegrove (2003)
DiprotodontiaPseudocheiridaePseudocheirus peregrinus8612·282  White & Seymour (2003)
DiprotodontiaPseudocheiridaePseudocheirus peregrinus9162·402  White & Seymour (2003)
DiprotodontiaTarsipedidaeTarsipes rostratus100·16210·00·162White & Seymour (2003)
DiprotodontiaVombatidaeLasiorhinus latifrons25 00015·34127 348·216·001Lovegrove (2000)
DiprotodontiaVombatidaeLasiorhinus latifrons29 91716·690  White & Seymour (2003)
HyracoideaProcaviidaeDendrohyrax dorsalis2 2104·1902 210·04·190White & Seymour (2003)
HyracoideaProcaviidaeHeterohyrax brucei1 2873·7331 604·43·872Lovegrove (2000)
HyracoideaProcaviidaeHeterohyrax brucei2 0004·017  White & Seymour (2003)
HyracoideaProcaviidaeProcavia capensis2 2505·0212 458·04·954White & Seymour (2003)
HyracoideaProcaviidaeProcavia capensis2 4003·682  White & Seymour (2003)
HyracoideaProcaviidaeProcavia capensis2 7506·577  White & Seymour (2003)
InsectivoraChrysochloridaeAmblysomus hottentotus700·47370·00·473White & Seymour (2003)
InsectivoraChrysochloridaeChrysochloris asiatica330·22036·70·243Heusner (1991)
InsectivoraChrysochloridaeChrysochloris asiatica340·228  Lovegrove (2000)
InsectivoraChrysochloridaeChrysochloris asiatica440·287  White & Seymour (2003)
InsectivoraChrysochloridaeEremitalpa granti200·05622·80·069White & Seymour (2003)
InsectivoraChrysochloridaeEremitalpa granti26·10·086  Lovegrove (2000)
InsectivoraErinaceidaeAtelerix albiventris4500·828450·00·828White & Seymour (2003)
InsectivoraErinaceidaeEchinosorex gymnura721·22·816721·22·816White & Seymour (2003)
InsectivoraErinaceidaeErinaceus concolor822·71·937822·71·937White & Seymour (2003)
InsectivoraErinaceidaeErinaceus europaeus7501·8831 213·52·434White & Seymour (2003)
InsectivoraErinaceidaeErinaceus europaeus1 191·22·632  Lovegrove (2000)
InsectivoraErinaceidaeErinaceus europaeus2 0002·910  Heusner (1991)
InsectivoraErinaceidaeHemiechinus aethiopicus4500·628451·50·630White & Seymour (2003)
InsectivoraErinaceidaeHemiechinus aethiopicus4530·632  Lovegrove (2000)
InsectivoraErinaceidaeHemiechinus auritus3970·842398·50·845Lovegrove (2000)
InsectivoraErinaceidaeHemiechinus auritus4000·848  White & Seymour (2003)
InsectivoraErinaceidaeHylomys suillus57·80·33557·80·335White & Seymour (2003)
InsectivoraSoricidaeBlarina brevicauda20·40·33120·90·344Lovegrove (2000)
InsectivoraSoricidaeBlarina brevicauda20·50·366  White & Seymour (2003)
InsectivoraSoricidaeBlarina brevicauda20·70·290  Heusner (1991)
InsectivoraSoricidaeBlarina brevicauda22·10·397  Lovegrove (2003)
InsectivoraSoricidaeBlarina carolinensis10·20·18810·20·188White & Seymour (2003)
InsectivoraSoricidaeCrocidura crossei9·50·1179·80·121Lovegrove (2003)
InsectivoraSoricidaeCrocidura crossei10·20·125  White & Seymour (2003)
InsectivoraSoricidaeCrocidura flavescens33·20·24833·20·248White & Seymour (2003)
InsectivoraSoricidaeCrocidura hildegardeae100·14510·70·156White & Seymour (2003)
InsectivoraSoricidaeCrocidura hildegardeae11·50·167  Lovegrove (2000)
InsectivoraSoricidaeCrocidura leucodon11·70·16611·70·166Lovegrove (2003)
InsectivoraSoricidaeCrocidura luna11·80·13812·30·144White & Seymour (2003)
InsectivoraSoricidaeCrocidura luna12·80·150  Lovegrove (2000)
InsectivoraSoricidaeCrocidura olivieri38·30·32038·60·323Lovegrove (2000)
InsectivoraSoricidaeCrocidura olivieri38·90·326  White & Seymour (2003)
InsectivoraSoricidaeCrocidura poensis16·90·17017·10·172Lovegrove (2000)
InsectivoraSoricidaeCrocidura poensis17·30·173  White & Seymour (2003)
InsectivoraSoricidaeCrocidura russula9·60·13110·80·143Lovegrove (2003)
InsectivoraSoricidaeCrocidura russula10·10·166  Lovegrove (2000)
InsectivoraSoricidaeCrocidura russula10·40·128  White & Seymour (2003)
InsectivoraSoricidaeCrocidura russula13·70·150  Heusner (1991)
InsectivoraSoricidaeCrocidura suaveolens6·50·1056·90·112White & Seymour (2003)
InsectivoraSoricidaeCrocidura suaveolens6·80·110  Lovegrove (2003)
InsectivoraSoricidaeCrocidura suaveolens7·50·120  Heusner (1991)
InsectivoraSoricidaeCrocidura viaria14·70·12315·00·126White & Seymour (2003)
InsectivoraSoricidaeCrocidura viaria15·30·128  Lovegrove (2000)
InsectivoraSoricidaeCryptotis parva6·20·1076·30·164White & Seymour (2003)
InsectivoraSoricidaeCryptotis parva6·40·250  Lovegrove (2000)
InsectivoraSoricidaeNeomys anomalus13·10·37313·10·373White & Seymour (2003)
InsectivoraSoricidaeNeomys fodiens14·10·37316·00·328Lovegrove (2000)
InsectivoraSoricidaeNeomys fodiens17·10·310  Heusner (1991)
InsectivoraSoricidaeNeomys fodiens17·10·305  White & Seymour (2003)
InsectivoraSoricidaeNotiosorex crawfordi40·0744·00·074White & Seymour (2003)
InsectivoraSoricidaeSorex alpinus7·80·2657·80·267Lovegrove (2000)
InsectivoraSoricidaeSorex alpinus7·90·269  White & Seymour (2003)
InsectivoraSoricidaeSorex araneus8·050·3368·40·348White & Seymour (2003)
InsectivoraSoricidaeSorex araneus8·70·361  Lovegrove (2003)
InsectivoraSoricidaeSorex cinereus3·50·1765·20·238White & Seymour (2003)
InsectivoraSoricidaeSorex cinereus50·249  Lovegrove (2000)
InsectivoraSoricidaeSorex cinereus7·90·310  Heusner (1991)
InsectivoraSoricidaeSorex coronatus9·10·2909·10·290White & Seymour (2003)
InsectivoraSoricidaeSorex minutus3·80·1824·10·179Lovegrove (2003)
InsectivoraSoricidaeSorex minutus40·172  White & Seymour (2003)
InsectivoraSoricidaeSorex minutus4·20·183  Lovegrove (2000)
InsectivoraSoricidaeSorex minutus4·60·180  Heusner (1991)
InsectivoraSoricidaeSorex ornatus9·70·2929·70·292White & Seymour (2003)
InsectivoraSoricidaeSorex vagrans5·20·1575·20·157White & Seymour (2003)
InsectivoraSoricidaeSuncus etruscus2·40·0802·40·063White & Seymour (2003)
InsectivoraSoricidaeSuncus etruscus2·50·050  Heusner (1991)
InsectivoraSoricidaeSuncus murinus30·20·33239·70·403White & Seymour (2003)
InsectivoraSoricidaeSuncus murinus52·30·490  Heusner (1991)
InsectivoraTalpidaeCondylura cristata490·61549·00·615White & Seymour (2003)
InsectivoraTalpidaeNeurotrichus gibbsii11·80·25911·80·259White & Seymour (2003)
InsectivoraTalpidaeScalopus aquaticus480·37848·00·378White & Seymour (2003)
InsectivoraTalpidaeScapanus latimanus610·42561·00·425White & Seymour (2003)
InsectivoraTalpidaeScapanus orarius61·20·35861·20·358White & Seymour (2003)
InsectivoraTalpidaeScapanus townsendii130·10·607130·10·607Lovegrove (2000)
InsectivoraTenrecidaeEchinops telfairi116·40·750116·40·750Heusner (1991)
InsectivoraTenrecidaeGeogale aurita6·90·0436·90·043White & Seymour (2003)
InsectivoraTenrecidaeHemicentetes semispinosus101·90·404116·40·380White & Seymour (2003)
InsectivoraTenrecidaeHemicentetes semispinosus1330·358  White & Seymour (2003)
InsectivoraTenrecidaeLimnogale mergulus77·70·31277·70·355White & Seymour (2003)
InsectivoraTenrecidaeLimnogale mergulus77·70·404  Lovegrove (2000)
InsectivoraTenrecidaeMicrogale cowani12·20·17912·20·179White & Seymour (2003)
InsectivoraTenrecidaeMicrogale dobsoni44·60·31544·60·315White & Seymour (2003)
InsectivoraTenrecidaeMicrogale talazaci440·24344·00·243White & Seymour (2003)
InsectivoraTenrecidaeSetifer setosus3450·483427·60·573Lovegrove (2000)
InsectivoraTenrecidaeSetifer setosus5300·680  White & Seymour (2003)
InsectivoraTenrecidaeTenrec ecaudatus6500·729650·00·729White & Seymour (2003)
LagomorphaLeporidaeBrachylagus idahoensis4322·145432·02·145Lovegrove (2003)
LagomorphaLeporidaeLepus alleni3 0009·2053 200·49·220White & Seymour (2003)
LagomorphaLeporidaeLepus alleni3 2509·972  Lovegrove (2000)
LagomorphaLeporidaeLepus alleni3 3628·540  Heusner (1991)
LagomorphaLeporidaeLepus americanus1 3805·2351 603·46·708Hart (1971)
LagomorphaLeporidaeLepus americanus1 4806·605  Hart (1971)
LagomorphaLeporidaeLepus americanus1 562·86·975  Lovegrove (2000)
LagomorphaLeporidaeLepus americanus1 5818·468  White & Seymour (2003)
LagomorphaLeporidaeLepus americanus2 1006·650  Heusner (1991)
LagomorphaLeporidaeLepus arcticus3 004·46·0363 004·46·036White & Seymour (2003)
LagomorphaLeporidaeLepus californicus2 3007·3142 300·07·314White & Seymour (2003)
LagomorphaLeporidaeLepus timidus3 0046·0333 014·58·443Lovegrove (2000)
LagomorphaLeporidaeLepus timidus3 02511·815  White & Seymour (2003)
LagomorphaLeporidaeLepus townsendii2 4307·0512 523·27·698White & Seymour (2003)
LagomorphaLeporidaeLepus townsendii2 6208·404  Lovegrove (2000)
LagomorphaLeporidaeOryctolagus cuniculus2 0006·3602167·97·395White & Seymour (2003)
LagomorphaLeporidaeOryctolagus cuniculus2 3508·600  Heusner (1991)
LagomorphaLeporidaeSylvilagus audubonii672·42·443686·92·506White & Seymour (2003)
LagomorphaLeporidaeSylvilagus audubonii701·72·570  Heusner (1991)
LagomorphaOchotonidaeOchotona dauurica127·71·389127·71·389White & Seymour (2003)
LagomorphaOchotonidaeOchotona princeps1090·932109·00·932White & Seymour (2003)
MacroscelidaeMacroscelididaeElephantulus brachyrhynchus45·30·24445·30·244White & Seymour (2003)
MacroscelidaeMacroscelididaeElephantulus edwardii49·80·30349·90·303Lovegrove (2000)
MacroscelidaeMacroscelididaeElephantulus edwardii500·304  White & Seymour (2003)
MacroscelidaeMacroscelididaeElephantulus intufi46·490·29046·50·290White & Seymour (2003)
MacroscelidaeMacroscelididaeElephantulus myurus610·35863·00·387Lovegrove (2003)
MacroscelidaeMacroscelididaeElephantulus myurus62·970·370  White & Seymour (2003)
MacroscelidaeMacroscelididaeElephantulus myurus65·20·436  Lovegrove (2000)
MacroscelidaeMacroscelididaeElephantulus rozeti45·310·26749·00·288White & Seymour (2003)
MacroscelidaeMacroscelididaeElephantulus rozeti530·312  Lovegrove (2003)
MacroscelidaeMacroscelididaeElephantulus rufescens530·31753·00·317White & Seymour (2003)
MacroscelidaeMacroscelididaeMacroscelides proboscideus390·29239·00·292White & Seymour (2003)
MacroscelidaeMacroscelididaePetrodromus tetradactylus206·11·001208·00·852Lovegrove (2003)
MacroscelidaeMacroscelididaePetrodromus tetradactylus2080·859  Lovegrove (2000)
MacroscelidaeMacroscelididaePetrodromus tetradactylus2100·720  Heusner (1991)
MonotremataOrnithorhynchidaeOrnithorhynchus anatinus6931·0821 030·31·931White & Seymour (2003)
MonotremataOrnithorhynchidaeOrnithorhynchus anatinus1 2002·500  Heusner (1991)
MonotremataOrnithorynchidaeOrnithorhynchus anatinus1 3152·663  Lovegrove (2000)
MonotremataTachyglossidaeTachyglossus aculeatus2 1401·5642 909·02·327Lovegrove (2000)
MonotremataTachyglossidaeTachyglossus aculeatus2 7252·404  White & Seymour (2003)
MonotremataTachyglossidaeTachyglossus aculeatus3 4302·550  Heusner (1991)
MonotremataTachyglossidaeTachyglossus aculeatus3 5803·056  Lovegrove (2000)
MonotremataTachyglossidaeZaglossus bruijni10 3006·77811 848·66·493White & Seymour (2003)
MonotremataTachyglossidaeZaglossus bruijni13 6306·220  Heusner (1991)
NotoryctomorphiaNotoryctidaeNotoryctes caurinus340·11934·00·119White & Seymour (2003)
PeramelemorphiaPeramelidaeIsoodon auratus4280·837428·00·837White & Seymour (2003)
PeramelemorphiaPeramelidaeIsoodon macrourus1 5513·2021 551·03·202White & Seymour (2003)
PeramelemorphiaPeramelidaeIsoodon obesulus7171·238717·01·238White & Seymour (2003)
PeramelemorphiaPeramelidaeMacrotis lagotis1 0111·9741 245·52·400Lovegrove (2000)
PeramelemorphiaPeramelidaeMacrotis lagotis1 2942·510  White & Seymour (2003)
PeramelemorphiaPeramelidaeMacrotis lagotis1 4772·790  Heusner (1991)
PeramelemorphiaPeramelidaePerameles gunnii8372·343837·02·343White & Seymour (2003)
PeramelemorphiaPeramelidaePerameles nasuta6451·763645·01·763White & Seymour (2003)
PeramelemorphiaPeroryctidaeEchymipera rufescens6161·685886·62·255White & Seymour (2003)
PeramelemorphiaPeroryctidaeEchymipera rufescens1 2763·018  White & Seymour (2003)
PeramelemorphiaPeroryctidaePerameles gunnii6951·902695·01·902White & Seymour (2003)
PerissodactylaEquidaeEquus asinus177 500164·920177 500·0164·920Heusner (1991)
PholidotaManidaeManis crassicaudata15 9106·92315 910·06·923White & Seymour (2003)
PholidotaManidaeManis javanica4 2206·2304 220·06·230Heusner (1991)
PholidotaManidaeManis pentadactyla3 637·53·7273 637·53·727White & Seymour (2003)
PholidotaManidaeManis tetradactyla1 4301·2781 430·01·278White & Seymour (2003)
PholidotaManidaeManis tricuspis1 3651·5401 930·42·670White & Seymour (2003)
PholidotaManidaeManis tricuspis2 7304·630  Heusner (1991)
PrimatesCallitrichidaeCallithrix jacchus1900·848190·00·848White & Seymour (2003)
PrimatesCallitrichidaeCallithrix pygmaea1050·550110·70·599Heusner (1991)
PrimatesCallitrichidaeCallithrix pygmaea116·80·653  White & Seymour (2003)
PrimatesCallitrichidaeSaguinus geoffroyi2251·305225·01·305White & Seymour (2003)
PrimatesCebidaeAlouatta palliata4 67011·4644 670·011·464White & Seymour (2003)
PrimatesCebidaeAotus trivirgatus8202·466914·52·499White & Seymour (2003)
PrimatesCebidaeAotus trivirgatus1 0202·532  Lovegrove (2000)
PrimatesCebidaeSaimiri sciureus8004·390836·74·429Heusner (1991)
PrimatesCebidaeSaimiri sciureus8754·468  White & Seymour (2003)
PrimatesCercopithecidaeCercopithecus mitis8 50018·9238 648·719·276White & Seymour (2003)
PrimatesCercopithecidaeCercopithecus mitis8 80019·637  Lovegrove (2000)
PrimatesCercopithecidaeColobus guereza10 45016·61310 623·617·037White & Seymour (2003)
PrimatesCercopithecidaeColobus guereza10 80017·472  Lovegrove (2000)
PrimatesCercopithecidaeErythrocebus patas3 0005·9583 000·05·958White & Seymour (2003)
PrimatesCercopithecidaePapio hamadryas9 50015·49712 670·821·095White & Seymour (2003)
PrimatesCercopithecidaePapio hamadryas16 90028·713  White & Seymour (2003)
PrimatesCheirogaleidaeCheirogaleus medius3001·088300·01·088White & Seymour (2003)
PrimatesHominidaeHomo sapiens sapiens70 00082·78070 000·082·780Heusner (1991)
PrimatesIndriidaePropithecus verreauxi3 3503·7383 350·03·738White & Seymour (2003)
PrimatesLemuridaeEulemur fulvus2 3304·1622 374·14·239White & Seymour (2003)
PrimatesLemuridaeEulemur fulvus2 4194·318  Lovegrove (2000)
PrimatesLorisidaeArctocebus calabarensis2060·731206·00·731White & Seymour (2003)
PrimatesLorisidaeEuoticus elegantulus261·51·205261·51·205White & Seymour (2003)
PrimatesLorisidaeGalago moholi1700·285170·00·285White & Seymour (2003)
PrimatesLorisidaeGalago senegalensis171·50·764171·50·764White & Seymour (2003)
PrimatesLorisidaeGalagoides demidoff610·42062·40·372Heusner (1991)
PrimatesLorisidaeGalagoides demidoff63·80·329  White & Seymour (2003)
PrimatesLorisidaeLoris tardigradus2840·714284·00·714White & Seymour (2003)
PrimatesLorisidaeNycticebus coucang953·31·2921 128·61·504Lovegrove (2000)
PrimatesLorisidaeNycticebus coucang1 1601·523  White & Seymour (2003)
PrimatesLorisidaeNycticebus coucang1 3001·730  Heusner (1991)
PrimatesLorisidaeOtolemur crassicaudatus9502·298993·52·595White & Seymour (2003)
PrimatesLorisidaeOtolemur crassicaudatus1 0392·930  Heusner (1991)
PrimatesLorisidaeOtolemur garnettii1 3143·9271 314·03·927White & Seymour (2003)
PrimatesLorisidaePerodicticus potto932·51·940968·61·942Lovegrove (2000)
PrimatesLorisidaePerodicticus potto9641·824  White & Seymour (2003)
PrimatesLorisidaePerodicticus potto1 0112·070  Heusner (1991)
PrimatesTarsiidaeTarsius spectrum1730·831173·00·831White & Seymour (2003)
PrimatesTarsiidaeTarsius syrichta1130·430113·00·430White & Seymour (2003)
ProboscideaElphantidaeElephas maximus3 672 0002336·5003 672 000·02336·500Heusner (1991)
RodentiaAgoutidaeAgouti paca9 15615·3239 156·015·323White & Seymour (2003)
RodentiaAplodontidaeAplodontia rufa6301·546706·81·892White & Seymour (2003)
RodentiaAplodontidaeAplodontia rufa7932·314  Lovegrove (2000)
RodentiaBathyergidaeBathyergus janetta4061·201406·01·201White & Seymour (2003)
RodentiaBathyergidaeBathyergus suillus6201·695664·41·798White & Seymour (2003)
RodentiaBathyergidaeBathyergus suillus7121·907  Lovegrove (2000)
RodentiaBathyergidaeCryptomys bocagei940·38894·00·388White & Seymour (2003)
RodentiaBathyergidaeCryptomys damarensis1250·397131·30·418Lovegrove (2000)
RodentiaBathyergidaeCryptomys damarensis1380·439  White & Seymour (2003)
RodentiaBathyergidaeCryptomys hottentotus600·32878·90·350Lovegrove (2000)
RodentiaBathyergidaeCryptomys hottentotus710·380  Heusner (1991)
RodentiaBathyergidaeCryptomys hottentotus750·377  White & Seymour (2003)
RodentiaBathyergidaeCryptomys hottentotus770·271  Lovegrove (2000)
RodentiaBathyergidaeCryptomys hottentotus79·50·310  White & Seymour (2003)
RodentiaBathyergidaeCryptomys hottentotus950·360  Lovegrove (2000)
RodentiaBathyergidaeCryptomys hottentotus1020·455  White & Seymour (2003)
RodentiaBathyergidaeCryptomys mechowi2670·894269·50·902White & Seymour (2003)
RodentiaBathyergidaeCryptomys mechowi2720·910  Lovegrove (2000)
RodentiaBathyergidaeGeorychus capensis1910·629193·00·637Lovegrove (2000)
RodentiaBathyergidaeGeorychus capensis1950·645  White & Seymour (2003)
RodentiaBathyergidaeHeliophobius argenteocinereus880·42088·50·430Heusner (1991)
RodentiaBathyergidaeHeliophobius argenteocinereus890·440  Heusner (1991)
RodentiaBathyergidaeHeterocephalus glaber320·11435·30·128White & Seymour (2003)
RodentiaBathyergidaeHeterocephalus glaber390·144  Lovegrove (2000)
RodentiaCapromyidaeCapromys pilorides2 6303·3752 630·03·375White & Seymour (2003)
RodentiaCapromyidaeGeocapromys brownii2 4564·1102 456·04·110White & Seymour (2003)
RodentiaCapromyidaeGeocapromys ingrahami7751·483775·01·483White & Seymour (2003)
RodentiaCaviidaeCavia porcellus5702·226639·12·130Hart (1971)
RodentiaCaviidaeCavia porcellus6291·930  White & Seymour (2003)
RodentiaCaviidaeCavia porcellus7282·250  Heusner (1991)
RodentiaCaviidaeDolichotis salinicola1 6134·0501 613·04·050White & Seymour (2003)
RodentiaCaviidaeGalea musteloides3221·473322·01·473White & Seymour (2003)
RodentiaCaviidaeKerodon rupestris8012·011801·02·011White & Seymour (2003)
RodentiaCaviidaeMicrocavia niata2550·980255·00·980White & Seymour (2003)
RodentiaChinchillidaeChinchilla lanigera4031·574436·71·310Lovegrove (2000)
RodentiaChinchillidaeChinchilla lanigera4261·117  White & Seymour (2003)
RodentiaChinchillidaeChinchilla lanigera4851·280  Heusner (1991)
RodentiaChinchillidaeLagostomus maximus6 78410·5976 794·010·623Lovegrove (2000)
RodentiaChinchillidaeLagostomus maximus6 80410·650  Heusner (1991)
RodentiaCtenomyidaeCtenomys australis3400·650340·00·650White & Seymour (2003)
RodentiaCtenomyidaeCtenomys fulvus3001·054300·01·054White & Seymour (2003)
RodentiaCtenomyidaeCtenomys maulinus2151·044215·01·044White & Seymour (2003)
RodentiaCtenomyidaeCtenomys peruanus4901·230490·01·230White & Seymour (2003)
RodentiaCtenomyidaeCtenomys talarum1210·611121·00·611White & Seymour (2003)
RodentiaDasyproctidaeDasyprocta azarae3 84910·5213 849·010·521White & Seymour (2003)
RodentiaDasyproctidaeDasyprocta leporina2 6878·6942 687·08·694White & Seymour (2003)
RodentiaDasyproctidaeMyoprocta acouchy9142·804914·02·804White & Seymour (2003)
RodentiaDipodidaeDipus sagitta?1600·676160·00·676White & Seymour (2003)
RodentiaDipodidaeJaculus jaculus750·51575·00·515White & Seymour (2003)
RodentiaDipodidaeJaculus orientalis1390·775139·00·775White & Seymour (2003)
RodentiaDipodidaeNapaeozapus insignis21·60·22021·80·220Heusner (1991)
RodentiaDipodidaeNapaeozapus insignis220·221  White & Seymour (2003)
RodentiaDipodidaeSicista betulina100·17910·00·179White & Seymour (2003)
RodentiaDipodidaeZapus hudsonius23·80·19926·10·219White & Seymour (2003)
RodentiaDipodidaeZapus hudsonius250·209  Hart (1971)
RodentiaDipodidaeZapus hudsonius300·251  Lovegrove (2000)
RodentiaEchimyidaeProechimys semispinosus4981·750498·01·750White & Seymour (2003)
RodentiaEchimyidaeThrichomys apereoides3231·153323·01·153White & Seymour (2003)
RodentiaErethizontidaeCoendou prehensilis3 2805·1233 280·05·123White & Seymour (2003)
RodentiaErethizontidaeErethizon dorsatum4 29011·9666 871·013·675Hart (1971)
RodentiaErethizontidaeErethizon dorsatum6 79013·760  Heusner (1991)
RodentiaErethizontidaeErethizon dorsatum11 13615·531  White & Seymour (2003)
RodentiaGeomyidaeGeomys bursarius1970·769197·00·769Bradley & Yousef (1975)
RodentiaGeomyidaeGeomys pinetis1730·743191·50·768White & Seymour (2003)
RodentiaGeomyidaeGeomys pinetis2000·792  Lovegrove (2000)
RodentiaGeomyidaeGeomys pinetis2030·770  Heusner (1991)
RodentiaGeomyidaeThomomys bottae1430·670143·00·670White & Seymour (2003)
RodentiaGeomyidaeThomomys talpoides82·60·55097·60·679Heusner (1991)
RodentiaGeomyidaeThomomys talpoides105·50·719  Lovegrove (2000)
RodentiaGeomyidaeThomomys talpoides106·80·792  White & Seymour (2003)
RodentiaGeomyidaeThomomys umbrinus850·40390·00·427White & Seymour (2003)
RodentiaGeomyidaeThomomys umbrinus95·30·452  Lovegrove (2000)
RodentiaHeteromyidaeChaetodipus baileyi29·10·19229·10·192White & Seymour (2003)
RodentiaHeteromyidaeChaetodipus californicus220·11922·00·119White & Seymour (2003)
RodentiaHeteromyidaeChaetodipus fallax19·60·15019·60·150Hinds & MacMillen (1985)
RodentiaHeteromyidaeChaetodipus formosus15·10·10315·10·103Lovegrove (2003)
RodentiaHeteromyidaeChaetodipus hispidus320·25635·60·266Lovegrove (2003)
RodentiaHeteromyidaeChaetodipus hispidus35·80·268  Lovegrove (2000)
RodentiaHeteromyidaeChaetodipus hispidus39·50·276  White & Seymour (2003)
RodentiaHeteromyidaeChaetodipus intermedius14·60·08715·90·106Lovegrove (2000)
RodentiaHeteromyidaeChaetodipus intermedius150·100  White & Seymour (2003)
RodentiaHeteromyidaeChaetodipus intermedius18·30·136  Lovegrove (2003)
RodentiaHeteromyidaeChaetodipus penicillatus160·12516·00·125White & Seymour (2003)
RodentiaHeteromyidaeDipodomys agilis60·60·35560·60·355White & Seymour (2003)
RodentiaHeteromyidaeDipodomys deserti104·70·541105·80·517Lovegrove (2003)
RodentiaHeteromyidaeDipodomys deserti104·90·524  Lovegrove (2000)
RodentiaHeteromyidaeDipodomys deserti1060·514  White & Seymour (2003)
RodentiaHeteromyidaeDipodomys deserti107·50·490  Heusner (1991)
RodentiaHeteromyidaeDipodomys heermanni63·30·40863·30·408White & Seymour (2003)
RodentiaHeteromyidaeDipodomys merriami350·23437·60·246Hart (1971)
RodentiaHeteromyidaeDipodomys merriami35·80·295  Lovegrove (2003)
RodentiaHeteromyidaeDipodomys merriami36·50·237  White & Seymour (2003)
RodentiaHeteromyidaeDipodomys merriami37·70·248  Lovegrove (2000)
RodentiaHeteromyidaeDipodomys merriami380·240  Hart (1971)
RodentiaHeteromyidaeDipodomys merriami43·40·230  Heusner (1991)
RodentiaHeteromyidaeDipodomys microps51·50·30554·60·335Lovegrove (2003)
RodentiaHeteromyidaeDipodomys microps54·20·330  Heusner (1991)
RodentiaHeteromyidaeDipodomys microps55·70·336  Lovegrove (2000)
RodentiaHeteromyidaeDipodomys microps57·20·373  White & Seymour (2003)
RodentiaHeteromyidaeDipodomys nitratoides37·80·25737·80·204White & Seymour (2003)
RodentiaHeteromyidaeDipodomys nitratoides37·80·162  Lovegrove (2003)
RodentiaHeteromyidaeDipodomys ordii46·80·35847·80·339White & Seymour (2003)
RodentiaHeteromyidaeDipodomys ordii48·80·320  Heusner (1991)
RodentiaHeteromyidaeDipodomys panamintinus56·90·38060·40·397Heusner (1991)
RodentiaHeteromyidaeDipodomys panamintinus64·20·414  White & Seymour (2003)
RodentiaHeteromyidaeHeteromys anomalus69·30·56169·30·561White & Seymour (2003)
RodentiaHeteromyidaeHeteromys desmarestianus75·80·55375·80·553White & Seymour (2003)
RodentiaHeteromyidaeLiomys irroratus44·90·33646·50·318Lovegrove (2003)
RodentiaHeteromyidaeLiomys irroratus48·10·301  White & Seymour (2003)
RodentiaHeteromyidaeLiomys salvini42·70·31343·70·281Lovegrove (2003)
RodentiaHeteromyidaeLiomys salvini43·80·262  White & Seymour (2003)
RodentiaHeteromyidaeLiomys salvini44·50·270  Lovegrove (2000)
RodentiaHeteromyidaeMicrodipodops megacephalus110·16811·00·168White & Seymour (2003)
RodentiaHeteromyidaeMicrodipodops pallidus15·20·11015·20·110Lovegrove (2000)
RodentiaHeteromyidaePerognathus flavus8·30·0978·30·097White & Seymour (2003)
RodentiaHeteromyidaePerognathus longimembris8·20·0708·50·061Lovegrove (2000)
RodentiaHeteromyidaePerognathus longimembris8·90·053  White & Seymour (2003)
RodentiaHeteromyidaePerognathus parvus19·20·16019·20·160Heusner (1991)
RodentiaHydrochaeridaeHydrochaeris hydrochaeris26 38536·79826 385·036·798White & Seymour (2003)
RodentiaHystricidaeHystrix africaeaustralis11 30013·17511 300·013·175White & Seymour (2003)
RodentiaMuridaeAcomys cahirinus420·25842·00·258White & Seymour (2003)
RodentiaMuridaeAcomys russatus51·10·23055·40·240Heusner (1991)
RodentiaMuridaeAcomys russatus55·550·239  White & Seymour (2003)
RodentiaMuridaeAcomys russatus600·251  Lovegrove (2003)
RodentiaMuridaeAcomys spinosissimus27·020·24627·00·246White & Seymour (2003)
RodentiaMuridaeAcomys subspinosus32·250·46532·30·465White & Seymour (2003)
RodentiaMuridaeAethomys namaquensis57·30·26962·60·292Lovegrove (2000)
RodentiaMuridaeAethomys namaquensis64·20·317  White & Seymour (2003)
RodentiaMuridaeAethomys namaquensis66·60·293  Lovegrove (2003)
RodentiaMuridaeAkodon albiventer310·25931·00·259White & Seymour (2003)
RodentiaMuridaeAkodon azarae23·50·22323·70·225Lovegrove (2000)
RodentiaMuridaeAkodon azarae240·228  White & Seymour (2003)
RodentiaMuridaeAkodon lanosus240·25424·00·254White & Seymour (2003)
RodentiaMuridaeAkodon longipilis42·30·32142·30·321White & Seymour (2003)
RodentiaMuridaeAkodon olivaceus270·27627·00·276White & Seymour (2003)
RodentiaMuridaeAlticola argentatus37·70·67537·70·675White & Seymour (2003)
RodentiaMuridaeApodemus agrarius21·20·37321·20·373Lovegrove (2003)
RodentiaMuridaeApodemus flavicollis23·40·23628·30·365Lovegrove (2003)
RodentiaMuridaeApodemus flavicollis23·90·242  White & Seymour (2003)
RodentiaMuridaeApodemus flavicollis40·50·850  Lovegrove (2000)
RodentiaMuridaeApodemus hermonensis20·50·27920·60·280White & Seymour (2003)
RodentiaMuridaeApodemus hermonensis20·70·282  Lovegrove (2000)
RodentiaMuridaeApodemus mystacinus40·40·31241·30·351White & Seymour (2003)
RodentiaMuridaeApodemus mystacinus42·30·394  Lovegrove (2000)
RodentiaMuridaeApodemus sylvaticus220·31823·80·264Lovegrove (2000)
RodentiaMuridaeApodemus sylvaticus23·90·242  White & Seymour (2003)
RodentiaMuridaeApodemus sylvaticus25·70·241  Lovegrove (2003)
RodentiaMuridaeArborimus longicaudus21·80·32921·80·329White & Seymour (2003)
RodentiaMuridaeArvicola terrestris920·59594·70·613White & Seymour (2003)
RodentiaMuridaeArvicola terrestris97·50·631  Lovegrove (2000)
RodentiaMuridaeAuliscomys boliviensis76·80·61776·80·617White & Seymour (2003)
RodentiaMuridaeAuliscomys micropus62·30·54662·30·546White & Seymour (2003)
RodentiaMuridaeBaiomys taylori7·150·0957·20·095White & Seymour (2003)
RodentiaMuridaeCalomys callosus480·31149·20·371Lovegrove (2000)
RodentiaMuridaeCalomys callosus49·50·395  Lovegrove (2000)
RodentiaMuridaeCalomys callosus50·10·417  White & Seymour (2003)
RodentiaMuridaeCalomys lepidus160·16116·00·161Lovegrove (2003)
RodentiaMuridaeCalomys musculinus16·90·15416·90·154White & Seymour (2003)
RodentiaMuridaeCannomys badius3440·960344·00·960White & Seymour (2003)
RodentiaMuridaeChionomys nivalis32·80·45232·80·452White & Seymour (2003)
RodentiaMuridaeChroeomys andinus34·60·36134·70·353White & Seymour (2003)
RodentiaMuridaeChroeomys andinus34·90·345  Lovegrove (2003)
RodentiaMuridaeClethrionomys californicus18·30·34118·30·341Lovegrove (2000)
RodentiaMuridaeClethrionomys gapperi22·30·27523·40·291White & Seymour (2003)
RodentiaMuridaeClethrionomys gapperi23·30·270  Lovegrove (2003)
RodentiaMuridaeClethrionomys gapperi24·60·332  Lovegrove (2000)
RodentiaMuridaeClethrionomys glareolus180·31121·50·312Hart (1971)
RodentiaMuridaeClethrionomys glareolus20·50·270  Heusner (1991)
RodentiaMuridaeClethrionomys glareolus23·40·354  White & Seymour (2003)
RodentiaMuridaeClethrionomys glareolus24·60·320  Lovegrove (2003)
RodentiaMuridaeClethrionomys rufocanus270·33127·20·321White & Seymour (2003)
RodentiaMuridaeClethrionomys rufocanus27·50·310  Heusner (1991)
RodentiaMuridaeClethrionomys rutilus280·43028·00·430White & Seymour (2003)
RodentiaMuridaeConilurus penicillatus213·20·908213·20·908White & Seymour (2003)
RodentiaMuridaeCricetomys gambianus1 521·45·7031 686·76·024Lovegrove (2000)
RodentiaMuridaeCricetomys gambianus1 8706·364  White & Seymour (2003)
RodentiaMuridaeCricetulus migratorius30·70·24530·70·245White & Seymour (2003)
RodentiaMuridaeCricetus cricetus336·71·190365·31·251Heusner (1991)
RodentiaMuridaeCricetus cricetus3621·293  White & Seymour (2003)
RodentiaMuridaeCricetus cricetus4001·272  Hart (1971)
RodentiaMuridaeDesmodillus auricularis71·930·49071·90·490White & Seymour (2003)
RodentiaMuridaeDicrostonyx groenlandicus470·52056·80·459Heusner (1991)
RodentiaMuridaeDicrostonyx groenlandicus59·620·551  White & Seymour (2003)
RodentiaMuridaeDicrostonyx groenlandicus610·391  Hart (1971)
RodentiaMuridaeDicrostonyx groenlandicus610·395  Hart (1971)
RodentiaMuridaeEligmodontia typus17·50·16717·50·167White & Seymour (2003)
RodentiaMuridaeEuneomys chinchilloides65·40·47165·40·471White & Seymour (2003)
RodentiaMuridaeGerbillurus paeba33·90·19433·90·194White & Seymour (2003)
RodentiaMuridaeGerbillurus setzeri46·10·20646·10·206White & Seymour (2003)
RodentiaMuridaeGerbillurus tytonis29·90·17729·90·177White & Seymour (2003)
RodentiaMuridaeGerbillurus vallinus38·80·19438·80·194White & Seymour (2003)
RodentiaMuridaeGerbillus allenbyi35·30·21735·30·217Lovegrove (2000)
RodentiaMuridaeGerbillus dasyurus27·60·16327·60·163White & Seymour (2003)
RodentiaMuridaeGerbillus gerbillus29·70·23729·70·237White & Seymour (2003)
RodentiaMuridaeGerbillus nanus28·40·12429·70·129White & Seymour (2003)
RodentiaMuridaeGerbillus nanus310·135  Lovegrove (2000)
RodentiaMuridaeGerbillus perpallidus52·40·24356·30·261White & Seymour (2003)
RodentiaMuridaeGerbillus perpallidus60·50·280  Lovegrove (2003)
RodentiaMuridaeGerbillus pusillus12·60·07512·60·075White & Seymour (2003)
RodentiaMuridaeGerbillus pyramidum108·50·454108·50·454White & Seymour (2003)
RodentiaMuridaeGolunda ellioti56·20·33956·20·339Lovegrove (2003)
RodentiaMuridaeGraomys griseoflavus69·40·46969·40·469White & Seymour (2003)
RodentiaMuridaeHydromys chrysogaster9002·970900·02·970Heusner (1991)
RodentiaMuridaeIsthmomys pirrensis137·90·677137·90·677White & Seymour (2003)
RodentiaMuridaeLasiopodomys brandtii40·20·42840·20·428White & Seymour (2003)
RodentiaMuridaeLemmiscus curtatus30·30·28130·30·281White & Seymour (2003)
RodentiaMuridaeLemmus lemmus801·07180·01·071White & Seymour (2003)
RodentiaMuridaeLemmus sibiricus50·20·50360·80·667White & Seymour (2003)
RodentiaMuridaeLemmus sibiricus640·882  Lovegrove (2000)
RodentiaMuridaeLemmus sibiricus700·670  Heusner (1991)
RodentiaMuridaeLemniscomys griselda47·50·32147·50·321White & Seymour (2003)
RodentiaMuridaeLemniscomys rosalia50·530·34350·50·343White & Seymour (2003)
RodentiaMuridaeMalacothrix typica21·70·11521·70·115White & Seymour (2003)
RodentiaMuridaeMastomys natalensis41·490·18341·50·183Lovegrove (2000)
RodentiaMuridaeMegadontomys thomasi110·80·692110·80·692White & Seymour (2003)
RodentiaMuridaeMeriones hurrianae690·30470·60·301White & Seymour (2003)
RodentiaMuridaeMeriones hurrianae72·30·298  Lovegrove (2003)
RodentiaMuridaeMeriones tristrami1120·550112·00·550White & Seymour (2003)
RodentiaMuridaeMeriones unguiculatus58·10·69064·80·546Lovegrove (2003)
RodentiaMuridaeMeriones unguiculatus670·430  White & Seymour (2003)
RodentiaMuridaeMeriones unguiculatus700·547  Hart (1971)
RodentiaMuridaeMesocricetus auratus980·820108·20·690White & Seymour (2003)
RodentiaMuridaeMesocricetus auratus119·50·580  Heusner (1991)
RodentiaMuridaeMicromys minutus60·2247·60·201Hart (1971)
RodentiaMuridaeMicromys minutus7·370·118  White & Seymour (2003)
RodentiaMuridaeMicromys minutus8·70·240  Heusner (1991)
RodentiaMuridaeMicromys minutus8·710·260  Heusner (1991)
RodentiaMuridaeMicrotus agrestis22·30·38025·00·367Heusner (1991)
RodentiaMuridaeMicrotus agrestis280·355  White & Seymour (2003)
RodentiaMuridaeMicrotus arvalis200·34621·90·343White & Seymour (2003)
RodentiaMuridaeMicrotus arvalis23·90·340  Heusner (1991)
RodentiaMuridaeMicrotus breweri53·10·41253·10·412White & Seymour (2003)
RodentiaMuridaeMicrotus californicus440·38044·00·380White & Seymour (2003)
RodentiaMuridaeMicrotus guentheri43·80·44743·80·447White & Seymour (2003)
RodentiaMuridaeMicrotus longicaudus28·60·37732·50·383White & Seymour (2003)
RodentiaMuridaeMicrotus longicaudus30·20·347  Lovegrove (2003)
RodentiaMuridaeMicrotus longicaudus31·20·410  Lovegrove (2000)
RodentiaMuridaeMicrotus longicaudus41·40·400  Heusner (1991)
RodentiaMuridaeMicrotus mexicanus280·26028·40·261Heusner (1991)
RodentiaMuridaeMicrotus mexicanus28·80·262  White & Seymour (2003)
RodentiaMuridaeMicrotus montanus30·80·45532·90·460Lovegrove (2000)
RodentiaMuridaeMicrotus montanus35·10·465  White & Seymour (2003)
RodentiaMuridaeMicrotus ochrogaster46·70·44148·20·410White & Seymour (2003)
RodentiaMuridaeMicrotus ochrogaster470·459  Lovegrove (2000)
RodentiaMuridaeMicrotus ochrogaster510·340  Heusner (1991)
RodentiaMuridaeMicrotus oeconomus320·57032·80·566Heusner (1991)
RodentiaMuridaeMicrotus oeconomus33·70·563  White & Seymour (2003)
RodentiaMuridaeMicrotus pennsylvanicus37·80·45738·20·428Lovegrove (2000)
RodentiaMuridaeMicrotus pennsylvanicus380·410  Heusner (1991)
RodentiaMuridaeMicrotus pennsylvanicus38·90·419  White & Seymour (2003)
RodentiaMuridaeMicrotus pinetorum23·80·31224·80·305Lovegrove (2003)
RodentiaMuridaeMicrotus pinetorum250·280  Heusner (1991)
RodentiaMuridaeMicrotus pinetorum25·50·326  White & Seymour (2003)
RodentiaMuridaeMicrotus richardsoni510·50064·50·701Heusner (1991)
RodentiaMuridaeMicrotus richardsoni65·650·714  White & Seymour (2003)
RodentiaMuridaeMicrotus richardsoni800·964  Lovegrove (2003)
RodentiaMuridaeMicrotus subterraneus17·80·27617·80·276White & Seymour (2003)
RodentiaMuridaeMicrotus townsendii52·20·50452·20·504White & Seymour (2003)
RodentiaMuridaeMicrotus xanthognathus68·50·55068·50·550White & Seymour (2003)
RodentiaMuridaeMillardia meltada67·40·32767·40·327White & Seymour (2003)
RodentiaMuridaeMus minutoides7·920·1248·00·129Lovegrove (2000)
RodentiaMuridaeMus minutoides8·060·134  White & Seymour (2003)
RodentiaMuridaeMus musculus13·20·36518·00·271Lovegrove (2003)
RodentiaMuridaeMus musculus170·160  Heusner (1991)
RodentiaMuridaeMus musculus260·340  Heusner (1991)
RodentiaMuridaeMus spretus21·80·34521·80·345White & Seymour (2003)
RodentiaMuridaeMyopus schisticolor26·40·52226·40·522White & Seymour (2003)
RodentiaMuridaeMystromys albicaudatus93·780·70793·80·707White & Seymour (2003)
RodentiaMuridaeNannospalax ehrenbergi1280·614133·80·585Lovegrove (2000)
RodentiaMuridaeNannospalax ehrenbergi1340·568  White & Seymour (2003)
RodentiaMuridaeNannospalax ehrenbergi1340·462  White & Seymour (2003)
RodentiaMuridaeNannospalax ehrenbergi1350·640  White & Seymour (2003)
RodentiaMuridaeNannospalax ehrenbergi1380·662  White & Seymour (2003)
RodentiaMuridaeNannospalax leucodon151·90·713183·30·760Lovegrove (2000)
RodentiaMuridaeNannospalax leucodon177·90·630  Heusner (1991)
RodentiaMuridaeNannospalax leucodon2010·830  White & Seymour (2003)
RodentiaMuridaeNannospalax leucodon2080·893  Hart (1971)
RodentiaMuridaeNeofiber alleni258·11·209258·11·209White & Seymour (2003)
RodentiaMuridaeNeotoma albigula172·40·720177·60·735Heusner (1991)
RodentiaMuridaeNeotoma albigula1830·750  White & Seymour (2003)
RodentiaMuridaeNeotoma cinerea205·10·941256·51·152White & Seymour (2003)
RodentiaMuridaeNeotoma cinerea320·91·410  Heusner (1991)
RodentiaMuridaeNeotoma fuscipes1870·824187·00·824White & Seymour (2003)
RodentiaMuridaeNeotoma lepida98·70·413112·50·460Lovegrove (2003)
RodentiaMuridaeNeotoma lepida1060·360  Heusner (1991)
RodentiaMuridaeNeotoma lepida1100·485  White & Seymour (2003)
RodentiaMuridaeNeotoma lepida113·40·517  Lovegrove (2000)
RodentiaMuridaeNeotoma lepida1380·554  Hart (1971)
RodentiaMuridaeNotomys alexis32·30·25232·30·252White & Seymour (2003)
RodentiaMuridaeNotomys cervinus33·20·24633·70·239Lovegrove (2000)
RodentiaMuridaeNotomys cervinus34·20·233  White & Seymour (2003)
RodentiaMuridaeOchrotomys nuttalli19·50·15119·50·151White & Seymour (2003)
RodentiaMuridaeOligoryzomys longicaudatus28·20·28528·20·285White & Seymour (2003)
RodentiaMuridaeOndatra zibethicus8423·890976·34·363Heusner (1991)
RodentiaMuridaeOndatra zibethicus1 004·63·586  White & Seymour (2003)
RodentiaMuridaeOndatra zibethicus1 1005·952  Hart (1971)
RodentiaMuridaeOnychomys torridus19·10·16519·10·165White & Seymour (2003)
RodentiaMuridaeOtomys irroratus1020·474102·00·474White & Seymour (2003)
RodentiaMuridaeOtomys sloggetti113·290·746113·30·746White & Seymour (2003)
RodentiaMuridaeOtomys unisulcatus960·59596·00·595White & Seymour (2003)
RodentiaMuridaeOxymycterus roberti83·50·50883·50·508White & Seymour (2003)
RodentiaMuridaeParotomys brantsii86·50·46886·50·468White & Seymour (2003)
RodentiaMuridaePeromyscus boylii23·20·30323·20·303White & Seymour (2003)
RodentiaMuridaePeromyscus californicus45·50·26147·00·267Lovegrove (2003)
RodentiaMuridaePeromyscus californicus47·60·292  White & Seymour (2003)
RodentiaMuridaePeromyscus californicus480·250  Heusner (1991)
RodentiaMuridaePeromyscus crinitus13·60·10020·50·162Heusner (1991)
RodentiaMuridaePeromyscus crinitus15·90·140  Lovegrove (2003)
RodentiaMuridaePeromyscus crinitus160·143  Hart (1971)
RodentiaMuridaePeromyscus crinitus20·90·173  Lovegrove (2003)
RodentiaMuridaePeromyscus crinitus49·60·324  White & Seymour (2003)
RodentiaMuridaePeromyscus eremicus200·17921·00·173Hart (1971)
RodentiaMuridaePeromyscus eremicus20·70·150  Heusner (1991)
RodentiaMuridaePeromyscus eremicus21·50·185  White & Seymour (2003)
RodentiaMuridaePeromyscus eremicus220·182  Lovegrove (2000)
RodentiaMuridaePeromyscus gossypinus21·50·20621·50·206White & Seymour (2003)
RodentiaMuridaePeromyscus leucopus200·18522·30·213White & Seymour (2003)
RodentiaMuridaePeromyscus leucopus21·40·189  Lovegrove (2000)
RodentiaMuridaePeromyscus leucopus22·10·205  Lovegrove (2003)
RodentiaMuridaePeromyscus leucopus22·30·190  Heusner (1991)
RodentiaMuridaePeromyscus leucopus260·319  Hart (1971)
RodentiaMuridaePeromyscus maniculatus170·17020·50·219Heusner (1991)
RodentiaMuridaePeromyscus maniculatus18·70·203  Lovegrove (2000)
RodentiaMuridaePeromyscus maniculatus18·930·220  White & Seymour (2003)
RodentiaMuridaePeromyscus maniculatus190·212  Hart (1971)
RodentiaMuridaePeromyscus maniculatus190·223  Hart (1971)
RodentiaMuridaePeromyscus maniculatus19·10·217  Lovegrove (2003)
RodentiaMuridaePeromyscus maniculatus19·530·222  White & Seymour (2003)
RodentiaMuridaePeromyscus maniculatus20·380·209  White & Seymour (2003)
RodentiaMuridaePeromyscus maniculatus220·245  Hart (1971)
RodentiaMuridaePeromyscus maniculatus22·80·206  White & Seymour (2003)
RodentiaMuridaePeromyscus maniculatus23·190·257  White & Seymour (2003)
RodentiaMuridaePeromyscus maniculatus24·20·225  Lovegrove (2003)
RodentiaMuridaePeromyscus maniculatus250·251  Hart (1971)
RodentiaMuridaePeromyscus megalops660·51566·10·511Hart (1971)
RodentiaMuridaePeromyscus megalops66·20·506  White & Seymour (2003)
RodentiaMuridaePeromyscus oreas24·580·24324·60·243White & Seymour (2003)
RodentiaMuridaePeromyscus polionotus120·12012·00·120Lovegrove (2003)
RodentiaMuridaePeromyscus sitkensis28·30·26128·30·261White & Seymour (2003)
RodentiaMuridaePeromyscus truei330·25633·10·307Lovegrove (2000)
RodentiaMuridaePeromyscus truei330·350  Hart (1971)
RodentiaMuridaePeromyscus truei33·20·283  White & Seymour (2003)
RodentiaMuridaePeromyscus truei33·30·349  White & Seymour (2003)
RodentiaMuridaePetromyscus collinus20·410·11520·40·115Lovegrove (2003)
RodentiaMuridaePhenacomys intermedius21·50·37521·50·375White & Seymour (2003)
RodentiaMuridaePhodopus sungorus25·70·22831·30·313White & Seymour (2003)
RodentiaMuridaePhodopus sungorus31·40·329  Lovegrove (2003)
RodentiaMuridaePhodopus sungorus33·20·300  Heusner (1991)
RodentiaMuridaePhodopus sungorus35·90·425  Lovegrove (2000)
RodentiaMuridaePhyllotis darwini360·25347·00·333Lovegrove (2000)
RodentiaMuridaePhyllotis darwini490·367  White & Seymour (2003)
RodentiaMuridaePhyllotis darwini590·398  White & Seymour (2003)
RodentiaMuridaePhyllotis magister62·80·38562·80·385White & Seymour (2003)
RodentiaMuridaePhyllotis xanthopygus550·31655·00·316White & Seymour (2003)
RodentiaMuridaePodomys floridanus30·80·28830·80·288White & Seymour (2003)
RodentiaMuridaePseudomys gracilicaudatus79·80·46779·80·467White & Seymour (2003)
RodentiaMuridaePseudomys hermannsburgensis12·20·13012·20·130White & Seymour (2003)
RodentiaMuridaeRattus colletti165·70·686165·70·686White & Seymour (2003)
RodentiaMuridaeRattus fuscipes760·47176·00·471White & Seymour (2003)
RodentiaMuridaeRattus lutreolus1090·353109·00·353White & Seymour (2003)
RodentiaMuridaeRattus norvegicus1601·339206·91·404Hart (1971)
RodentiaMuridaeRattus norvegicus1601·169  Hart (1971)
RodentiaMuridaeRattus norvegicus1700·948  Hart (1971)
RodentiaMuridaeRattus norvegicus1700·960  Heusner (1991)
RodentiaMuridaeRattus norvegicus2251·506  Hart (1971)
RodentiaMuridaeRattus norvegicus2502·092  Hart (1971)
RodentiaMuridaeRattus norvegicus3902·393  Hart (1971)
RodentiaMuridaeRattus rattus1170·770117·00·770Heusner (1991)
RodentiaMuridaeRattus sordidus1870·595187·00·595White & Seymour (2003)
RodentiaMuridaeRattus villosissimus1850·585215·30·690Lovegrove (2003)
RodentiaMuridaeRattus villosissimus250·60·813  White & Seymour (2003)
RodentiaMuridaeReithrodon auritus78·70·42878·70·428Lovegrove (2003)
RodentiaMuridaeReithrodontomys megalotis90·1309·00·130Heusner (1991)
RodentiaMuridaeRhabdomys pumilio39·60·17939·60·179White & Seymour (2003)
RodentiaMuridaeSaccostomus campestris61·30·28768·10·274White & Seymour (2003)
RodentiaMuridaeSaccostomus campestris75·70·261  Lovegrove (2003)
RodentiaMuridaeScotinomys teguina120·17412·00·174White & Seymour (2003)
RodentiaMuridaeScotinomys xerampelinus15·20·17815·20·178White & Seymour (2003)
RodentiaMuridaeSekeetamys calurus56·90·24863·60·274White & Seymour (2003)
RodentiaMuridaeSekeetamys calurus71·20·303  Lovegrove (2003)
RodentiaMuridaeSigmodon alleni137·81·134137·81·134White & Seymour (2003)
RodentiaMuridaeSigmodon fulviventer137·81·157137·81·157White & Seymour (2003)
RodentiaMuridaeSigmodon hispidus139·31·285159·61·085White & Seymour (2003)
RodentiaMuridaeSigmodon hispidus152·40·710  Heusner (1991)
RodentiaMuridaeSigmodon hispidus191·61·400  Lovegrove (2003)
RodentiaMuridaeSigmodon leucotis128·61·040128·61·040White & Seymour (2003)
RodentiaMuridaeSigmodon ochrognathus115·10·860115·10·860White & Seymour (2003)
RodentiaMuridaeSteatomys pratensis37·540·10537·50·105White & Seymour (2003)
RodentiaMuridaeStochomys longicaudatus82·330·55083·30·547Heusner (1991)
RodentiaMuridaeStochomys longicaudatus84·20·544  White & Seymour (2003)
RodentiaMuridaeTachyoryctes splendens1710·811197·00·856Hart (1971)
RodentiaMuridaeTachyoryctes splendens1910·842  White & Seymour (2003)
RodentiaMuridaeTachyoryctes splendens2340·920  Heusner (1991)
RodentiaMuridaeTatera afra106·51·016106·51·016White & Seymour (2003)
RodentiaMuridaeTatera indica86·80·42186·90·422Lovegrove (2003)
RodentiaMuridaeTatera indica870·422  White & Seymour (2003)
RodentiaMuridaeTatera leucogaster133·80·764145·20·752Lovegrove (2000)
RodentiaMuridaeTatera leucogaster157·620·740  White & Seymour (2003)
RodentiaMuridaeThallomys nigricauda124·70·382124·70·382Lovegrove (2000)
RodentiaMuridaeThallomys paedulcus132·40·487132·40·487White & Seymour (2003)
RodentiaMuridaeUromys caudimaculatus8123·184812·03·184White & Seymour (2003)
RodentiaMyoxidaeGraphiurus murinus38·430·22538·40·225Lovegrove (2003)
RodentiaMyoxidaeGraphiurus ocularis67·80·37067·80·370White & Seymour (2003)
RodentiaMyoxidaeMuscardinus avellanarius23·50·35123·50·351White & Seymour (2003)
RodentiaMyoxidaeMyoxus glis1520·500174·40·664Heusner (1991)
RodentiaMyoxidaeMyoxus glis2000·881  White & Seymour (2003)
RodentiaOctodontidaeAconaemys fuscus1120·675112·00·675White & Seymour (2003)
RodentiaOctodontidaeOctodon bridgesi176·11·023176·11·023White & Seymour (2003)
RodentiaOctodontidaeOctodon degus1930·949199·60·958White & Seymour (2003)
RodentiaOctodontidaeOctodon degus206·40·966  Lovegrove (2000)
RodentiaOctodontidaeOctodon lunatus173·20·957173·20·957White & Seymour (2003)
RodentiaOctodontidaeOctodontomys gliroides1520·729154·10·715White & Seymour (2003)
RodentiaOctodontidaeOctodontomys gliroides156·30·702  Lovegrove (2000)
RodentiaOctodontidaeOctomys mimax118·60·642118·60·642White & Seymour (2003)
RodentiaOctodontidaeSpalacopus cyanus109·50·520126·20·561Lovegrove (2000)
RodentiaOctodontidaeSpalacopus cyanus1350·596  White & Seymour (2003)
RodentiaOctodontidaeSpalacopus cyanus1360·570  Heusner (1991)
RodentiaOctodontidaeTympanoctomys barrerae71·40·43071·40·430White & Seymour (2003)
RodentiaPeditidaePedetes capensis2 3004·4272 300·04·427White & Seymour (2003)
RodentiaSciuridaeAmmospermophilus leucurus75·60·43994·10·511Lovegrove (2003)
RodentiaSciuridaeAmmospermophilus leucurus95·70·524  White & Seymour (2003)
RodentiaSciuridaeAmmospermophilus leucurus960·540  Heusner (1991)
RodentiaSciuridaeAmmospermophilus leucurus112·80·550  Heusner (1991)
RodentiaSciuridaeCynomys ludovicianus1 112·32·3581 112·32·358White & Seymour (2003)
RodentiaSciuridaeEpixerus wilsoni4601·347460·01·347White & Seymour (2003)
RodentiaSciuridaeFunisciurus anerythrus630·58063·00·580Heusner (1991)
RodentiaSciuridaeFunisciurus congicus112·30·533112·30·533White & Seymour (2003)
RodentiaSciuridaeFunisciurus isabella600·57060·00·570White & Seymour (2003)
RodentiaSciuridaeFunisciurus lemniscatus950·50095·00·500Heusner (1991)
RodentiaSciuridaeFunisciurus pyrrhopus2441·011244·01·011White & Seymour (2003)
RodentiaSciuridaeGlaucomys volans62·80·37067·40·414Heusner (1991)
RodentiaSciuridaeGlaucomys volans64·250·377  White & Seymour (2003)
RodentiaSciuridaeGlaucomys volans760·509  Lovegrove (2000)
RodentiaSciuridaeHeliosciurus rufobrachium2300·744230·00·744White & Seymour (2003)
RodentiaSciuridaeMarmota flaviventris4 2958·6264 295·08·626White & Seymour (2003)
RodentiaSciuridaeMarmota monax2 6503·6962 650·03·696White & Seymour (2003)
RodentiaSciuridaeParaxerus cepapi223·60·811223·60·811White & Seymour (2003)
RodentiaSciuridaeParaxerus palliatus2060·977274·81·191White & Seymour (2003)
RodentiaSciuridaeParaxerus palliatus366·61·452  White & Seymour (2003)
RodentiaSciuridaeSciurus aberti6242·402624·02·402White & Seymour (2003)
RodentiaSciuridaeSciurus carolinensis4402·062440·02·062White & Seymour (2003)
RodentiaSciuridaeSpermophilus armatus3071·062313·20·915Lovegrove (2000)
RodentiaSciuridaeSpermophilus armatus312·80·880  Heusner (1991)
RodentiaSciuridaeSpermophilus armatus3200·821  White & Seymour (2003)
RodentiaSciuridaeSpermophilus beecheyi599·61·773599·61·773White & Seymour (2003)
RodentiaSciuridaeSpermophilus beldingi288·560·800293·70·796Heusner (1991)
RodentiaSciuridaeSpermophilus beldingi289·80·889  Lovegrove (2000)
RodentiaSciuridaeSpermophilus beldingi3030·710  White & Seymour (2003)
RodentiaSciuridaeSpermophilus citellus2401·272240·01·272White & Seymour (2003)
RodentiaSciuridaeSpermophilus franklinii6072·190607·02·190Heusner (1991)
RodentiaSciuridaeSpermophilus lateralis217·61·317249·60·967Lovegrove (2000)
RodentiaSciuridaeSpermophilus lateralis2370·800  White & Seymour (2003)
RodentiaSciuridaeSpermophilus lateralis270·160·740  Heusner (1991)
RodentiaSciuridaeSpermophilus lateralis278·71·119  Lovegrove (2003)
RodentiaSciuridaeSpermophilus mohavensis2400·629240·00·629White & Seymour (2003)
RodentiaSciuridaeSpermophilus parryii6502·901650·02·901White & Seymour (2003)
RodentiaSciuridaeSpermophilus richardsonii252·30·901266·30·788Lovegrove (2000)
RodentiaSciuridaeSpermophilus richardsonii273·070·740  Heusner (1991)
RodentiaSciuridaeSpermophilus richardsonii2740·734  White & Seymour (2003)
RodentiaSciuridaeSpermophilus saturatus252·20·900256·60·849Lovegrove (2000)
RodentiaSciuridaeSpermophilus saturatus261·150·800  Heusner (1991)
RodentiaSciuridaeSpermophilus spilosoma157·80·500170·40·543Heusner (1991)
RodentiaSciuridaeSpermophilus spilosoma1740·514  White & Seymour (2003)
RodentiaSciuridaeSpermophilus spilosoma180·30·624  Lovegrove (2000)
RodentiaSciuridaeSpermophilus tereticaudus90·80·334125·10·501Lovegrove (2003)
RodentiaSciuridaeSpermophilus tereticaudus1290·720  Hart (1971)
RodentiaSciuridaeSpermophilus tereticaudus1670·522  White & Seymour (2003)
RodentiaSciuridaeSpermophilus townsendii212·520·600224·00·634Heusner (1991)
RodentiaSciuridaeSpermophilus townsendii2290·587  White & Seymour (2003)
RodentiaSciuridaeSpermophilus townsendii2310·722  Lovegrove (2000)
RodentiaSciuridaeSpermophilus tridecemlineatus1820·579198·40·983Lovegrove (2000)
RodentiaSciuridaeSpermophilus tridecemlineatus205·40·783  White & Seymour (2003)
RodentiaSciuridaeSpermophilus tridecemlineatus2092·099  Hart (1971)
RodentiaSciuridaeSpermophilus undulatus5002·789698·03·601Hart (1971)
RodentiaSciuridaeSpermophilus undulatus6803·721  White & Seymour (2003)
RodentiaSciuridaeSpermophilus undulatus1 0004·500  Heusner (1991)
RodentiaSciuridaeTamias alpinus390·32239·00·322White & Seymour (2003)
RodentiaSciuridaeTamias amoenus52·70·43055·70·500Heusner (1991)
RodentiaSciuridaeTamias amoenus57·10·537  White & Seymour (2003)
RodentiaSciuridaeTamias amoenus57·30·540  Lovegrove (2003)
RodentiaSciuridaeTamias merriami750·44076·90·459White & Seymour (2003)
RodentiaSciuridaeTamias merriami78·90·480  Heusner (1991)
RodentiaSciuridaeTamias minimus45·80·40649·30·349White & Seymour (2003)
RodentiaSciuridaeTamias minimus530·300  Heusner (1991)
RodentiaSciuridaeTamias palmeri69·40·63169·40·631White & Seymour (2003)
RodentiaSciuridaeTamias striatus87·40·50289·60·813White & Seymour (2003)
RodentiaSciuridaeTamias striatus91·81·316  Lovegrove (2000)
RodentiaSciuridaeTamiasciurus hudsonicus2021·803219·61·615White & Seymour (2003)
RodentiaSciuridaeTamiasciurus hudsonicus2241·410  Heusner (1991)
RodentiaSciuridaeTamiasciurus hudsonicus2251·883  Hart (1971)
RodentiaSciuridaeTamiasciurus hudsonicus228·31·420  White & Seymour (2003)
RodentiaSciuridaeXerus inauris515·31·731528·51·775Lovegrove (2000)
RodentiaSciuridaeXerus inauris5421·820  White & Seymour (2003)
RodentiaSciuridaeXerus princeps6021·897614·41·936White & Seymour (2003)
RodentiaSciuridaeXerus princeps6271·976  Lovegrove (2000)
ScandentiaTupaiidaePtilocercus lowii57·50·24057·50·240Heusner (1991)
ScandentiaTupaiidaeTupaia glis1230·522123·00·522White & Seymour (2003)
ScandentiaTupaiidaeUrogale everetti260·61·250260·61·250White & Seymour (2003)
SireniaTrichechidaeTrichechus inunguis165 22364·520167 594·555·015Lovegrove (2000)
SireniaTrichechidaeTrichechus inunguis170 00046·910  Heusner (1991)
TubulidentataOrycteropodidaeOrycteropus afer48 00034·27548 000·034·275White & Seymour (2003)
XenarthraBradypodidaeBradypus variegatus3 7903·8273 790·03·827White & Seymour (2003)
XenarthraDasypodidaeCabassous centralis3 8104·5274 061·74·812Lovegrove (2000)
XenarthraDasypodidaeCabassous centralis4 3305·116  White & Seymour (2003)
XenarthraDasypodidaeChaetophractus nationi2 1503·1182 150·03·118White & Seymour (2003)
XenarthraDasypodidaeChaetophractus vellerosus1 1101·7071 110·01·707White & Seymour (2003)
XenarthraDasypodidaeChaetophractus villosus4 5404·5084 540·04·508White & Seymour (2003)
XenarthraDasypodidaeDasypus novemcinctus3 3204·4903 413·74·655Heusner (1991)
XenarthraDasypodidaeDasypus novemcinctus3 5104·825  White & Seymour (2003)
XenarthraDasypodidaeEuphractus sexcinctus8 1906·9018 190·06·901White & Seymour (2003)
XenarthraDasypodidaePriodontes maximus45 19016·89245 190·016·892White & Seymour (2003)
XenarthraDasypodidaeTolypeutes matacus1 1601·1721 160·01·172White & Seymour (2003)
XenarthraDasypodidaeZaedyus pichiy1 7402·1921 740·02·192White & Seymour (2003)
XenarthraMegalonychidaeCholoepus hoffmanni3 7703·3644 005·23·891White & Seymour (2003)
XenarthraMegalonychidaeCholoepus hoffmanni4 0103·892  Lovegrove (2000)
XenarthraMegalonychidaeCholoepus hoffmanni4 2504·500  Heusner (1991)
XenarthraMyrmecophagidaeCyclopes didactylus2400·636240·00·636White & Seymour (2003)
XenarthraMyrmecophagidaeMyrmecophaga tridactyla30 60014·54330 600·014·543White & Seymour (2003)
XenarthraMyrmecophagidaeTamandua mexicana3 5005·0773 884·25·124Lovegrove (2000)
XenarthraMyrmecophagidaeTamandua mexicana3 9775·534  White & Seymour (2003)
XenarthraMyrmecophagidaeTamandua mexicana4 2104·790  Heusner (1991)
XenarthraMyrmecophagidaeTamandua tetradactyla3 5005·0153 500·05·015White & Seymour (2003)

For the corrected, non-duplicate data, there were still multiple, independent values for the same species. In previous data sets, subspecies were often listed. We did not differentiate at the subspecies level. To address multiple data for the same species we calculated an average of the logarithms for each species, resulting in values for 626 species. The complete metabolic rate data set and the species averages are listed in Appendix 1. We then divided these species data into equally spaced logarithmic mass bins of size 0·1, resulting in 52 bins; thus, a typical bin covers a mass range from M to M + ΔM, where ΔM = 0·1M. All values within each bin were averaged to give a single data point for each size class. These values are also available in Appendix 2. Note that the values for M and BMR in Appendix 2 are computed from the average of the logarithms and then rounded. Then, the binned data were plotted, and since the error in the measurements of mass, corresponding to the x-axis, are much less than the error in the measurements of BMR, corresponding to the y-axis, regression lines were fitted using Ordinary Least Squares (OLS) (Type I) regression. By distributing samples uniformly with respect to mass, mass effectively becomes a treatment effect, and the regression statistics should reliably characterize the relationship between the dependent (logarithm of BMR) and independent (logarithm of M) variables. The slopes and confidence intervals represent the effects of mass on BMR.

Table Appendix 2. 
Binned log(mass (g))Binned log(BMR (W))Mass (g)BMR (W)
0·389 075 625−1·198 070 7082·40·063
0·568 201 724−1·571 328 8363·70·027
0·661 431 752−1·172 116 0154·60·067
0·745 139 266−0·968 529 7645·60·108
0·864 688 449−0·985 843 97·30·103
0·947 565 356−0·992 687 6418·90·102
1·052 690 015−0·884 366 83311·30·131
1·148 732 343−0·914 990 17514·10·122
1·243 318 579−0·784 506 41217·50·164
1·347 316 514−0·651 955 76622·20·223
1·454 764 674−0·612 176 62728·50·244
1·553 081 125−0·568 248 46635·70·270
1·656 886 834−0·512 975 40645·40·307
1·760 953 626−0·436 201 13857·70·366
1·844 213 326−0·355 015 96269·90·442
1·952 822 747−0·278 952 61389·70·526
2·055 702 395−0·232 303 347113·70·586
2·134 807 325−0·146 755 532136·40·713
2·253 844 347−0·135 624 546179·40·732
2·348 606 534−0·029 454 704223·20·934
2·439 805 622−0·001 765 502275·30·996
2·533 468 277 0·048 604 469341·61·118
2·645 402 525 0·045 198 384442·01·110
2·763 711 627 0·272 260 217580·41·872
2·838 103 042 0·292 155 678688·81·960
2·949 565 843 0·422 545 319890·42·646
3·048 280 513 0·365 582 3421 117·62·321
3·139 330 659 0·463 987 0911 378·32·911
3·237 087 401 0·604 685 2421 726·24·024
3·355 914 424 0·660 023 4152 269·44·571
3·446 405 262 0·727 139 5872 795·25·335
3·551 768 161 0·744 461 5243 562·65·552
3·643 742 43 0·867 574 0744 402·97·372
3·760 687 561 0·852 422 3085 763·57·119
3·859 428 015 1·091 854 6387 234·812·355
3·948 483 677 1·209 779 0168 881·416·210
4·031 997 885 1·187 784 3810 764·615·409
4·120 445 694 1·310 508 37813 196·120·441
4·201 670 18 0·840 297 86915 910·06·923
4·322 096 16 1·593 350 26120 994·039·206
4·448 180 523 1·543 794 69728 066·034·978
4·547 431 967 1·672 475 09935 272·247·041
4·668 141 789 1·381 329 62646 573·824·062
4·742 083 907 1·986 948 64455 218·497·040
4·830 810 77 1·925 241 60567 734·684·186
4·960 322 501 2·026 873 63291 268·8106·383
5·030 348 92 2·173 024 349107 238·1148·944
5·149 112 499 2·162 811 081140 965·4145·483
5·255 606 875 2·106 539 721180 138·6127·803
5·526 106 418 2·472 231 3  335 819·9296·641
5·609 594 409 2·351 755 691407 000·0224·779
6·564 902 673 3·368 565 7853 672 000·02 336·500

Results

The original data for all species together with the average values for the binned data are plotted in Fig. 1. A regression line (not shown) fitted to all data gives a slope of 0·712 (P < 0·0001, n = 626, 95% CI 0·699, 0·724). Notice that these 95% CI exclude both2/3 and 3/4. However, this analysis is biased by the disproportionately large representation of small body sizes. For our study there are 477 species with M < 1 kg, leaving only 149 species with M > 1 kg. After accounting for this bias by binning the data as described above in order to obtain a uniform distribution, the slope is 0·737 (P < 0·0001, n = 52, 95% CI 0·711, 0·762). The 95% CI include 3/4 and exclude 2/3. Thus, we find more support for an exponent of 3/4 than of 2/3.

question 2: how do other mammalian physiological rates scale?

There are two concerns in using BMR as a standard for assessing the scaling of metabolic rate and related physiological processes in mammals. First, BMR is notoriously difficult to measure according to the standard criteria. Metabolic rate is measured by a variety of techniques, including direct calorimetry, oxygen consumption and carbon dioxide production, and is known to vary with body temperature, activity and other factors (e.g. see Schmidt-Nielsen 1984 and McNab 2002). Therefore, it is difficult to ensure that individuals are in comparable physiological states, especially across the eight orders of magnitude variation in body size for mammals. Second, since BMR requires the individuals to be resting and fasting, it is not an energetic steady state and is of questionable biological relevance. At least as relevant are two other measures of metabolic rate commonly taken by physiologists. Field metabolic rate is a measure of the average rate of energy expenditure by free-living individuals under natural conditions. Maximal metabolic rate, or inline image, is the rate of energy expenditure during maximum aerobic activity. While there are also problems with standardizing these rates, they represent important measures of whole-organism performance that can be used to evaluate allometric scaling. The model of West et al. argues that natural selection has optimized the delivery rates of resources to cells, which is relevant to all levels of activity. Indeed, one might suspect that natural selection has operated primarily on field metabolic rate, not basal. The theory predicts that the primary differences among metabolic states will be reflected in the normalization constants (intercepts), i.e. B0,max > B0,field > B0,basal, but it does not preclude differences in the exponents, especially for maximal metabolic rate.

Allometric equations have been fitted to data for many structural and functional traits that are closely related to metabolic rate. The processes of resource supply require a high level of functional integration. In particular, characteristics of the circulatory and respiratory systems must be coordinated with metabolic rate. Indeed, the model of West et al. predicts the scaling exponents for 32 such characteristics (see Table 1 in West et al. 1997), many of which can be measured more accurately than metabolic rate. In particular, heart and respiratory rates, which are predicted to scale as M−1/4, have been measured in a variety of mammals. Consequently, analyses of these rates provide additional strong tests of the theory.

Table 1.  Regression statistics for annual biomass production and population-level energy use. The group ‘animals’ includes mammals, birds, fish, zooplankton, insects and the protist Paraphysomonas imperforata. Data from Ernest et al. (2003)
GroupSpp. no.Scaling exponent95% CINormalization constant95% CIr2
Production
Plants3870·7590·76–0·7510·1510·18–10·120·995
Mammals3050·7550·78–0·7310·2510·29–10·210·910
Birds 330·7400·85–0·6310·6610·79–10·530·858
Fish  90·7610·84–0·6810·8511·03–10·670·984
Animals3610·7190·74–0·7010·3010·34–10·260·934

Methods

Data for field metabolic rates were taken from Nagy, Girard & Brown (1999). Data for maximal metabolic rates were compiled from multiple sources (Pasquis, Lacaise & Dejours 1970; Hart 1971; Lechner 1978; Prothero 1979; Taylor et al. 1981; Taylor, Longworth & Hoppeler 1988; Bishop 1999; Sapoval, Filoche & Weibel 2002). We processed the maximal metabolic rate compilations in the same way as the BMR compilations. That is, duplicate data were identified in the maximal metabolic rate compilations, and only one datum was kept in each case. Then, for the non-duplicate data, we computed an average for each species. For both field and maximal metabolic rates, as for BMR, we divided the data into body size bins, calculated an average for each bin, and performed an OLS regression analysis on the averaged data. Data for heart rates are from Brody (1945), and we quote a reported value for the exponent for heart rates from Stahl (1967). Respiratory rates are taken from Calder (1968). Once again, we binned, averaged and calculated OLS regression statistics.

Results

In Fig. 2 we present the data for basal, field and maximal metabolic rates. The slopes of the regression lines for binned data for basal, field and maximal metabolic rates are 0·737 (P < 0·01, n = 52, 95% CI 0·711, 0·762), 0·749 (P < 0·0001, n = 35, 95% CI 0·695, 0·802) and 0·828 (P < 0·0001, n = 21, 95% CI 0·758, 0·897), respectively. The 95% CI for the exponents of basal and field metabolic rates include 3/4, while for maximal metabolic rate they exclude 3/4. The slope of the binned data for field metabolic rates is almost exactly 3/4 and very similar to that calculated by Nagy, Girard & Brown who treated each of the 79 species as an independent data point: 0·749 vs 0·744, respectively. The slope of the binned data for maximal metabolic rates is slightly higher than that obtained for the original unbinned data (n = 28): 0·828 vs 0·811. As expected, the normalization constants (intercepts) are different for the three metabolic states: at 1 kg the maximal rates from the regression equation are five times field rates and field rates are three times basal rates. We conclude that field and basal metabolic rates scale similarly with exponents very close to 3/4.

Figure 2.

Plots of the basal (Hart 1971; Heusner 1991; Lovegrove 2000; Lovegrove 2003; White & Seymour 2003), field (Nagy et al. 1999) and maximal metabolic rates (Pasquis et al. 1970; Hart 1971; Lechner 1978; Prothero 1979; Taylor et al. 1981; Taylor et al. 1988; Bishop 1999; Sapoval et al. 2002). The regression lines are fitted to the average of the logarithms for every 0·1 log unit interval of mass. This was done in order to give equal weighting to big and small mammals. For the basal metabolic rate only the averages are shown because the raw data is shown in Fig. 1. Both raw and averaged data for basal metabolic rate are shown in Fig. 1, but here only the averages (filled squares) are shown. For the field and maximal data, diamonds and stars are the average data, and bars and open squares are the raw data, respectively. While the slope for the maximal metabolic rate is slightly higher than that for the field or basal rates, all of the slopes are close to 3/4. The slope for basal is b = 0·737 (P < 0·0001, n = 52, 95% CI 0·711, 0·762), for field is 0·749 (P < 0·0001, n = 35, 95% CI 0·697, 0·801), and for maximal is 0·828 (P < 0·0001, n = 21, 95% CI 0·758, 0·897).

The exponent for maximal metabolic rates is greater than 3/4. Perhaps this can be explained by selection of species or methodological differences in addition to small sample size. Alternatively, it may well reflect a fundamental difference in the scaling of this process, perhaps due to vascular and respiratory adjustments, not operable under either field or basal conditions, that support maximal activity of the muscles used in exercise. Clearly, maximal metabolic rate does not scale as M2/3. This is especially relevant for considerations of surface area and heat dissipation because maximal metabolic rate maximizes heat production.

In Fig. 3 we plot the data for mammalian heart and respiratory rates. After binning, the slope for the heart rate is −0·251 (P < 0·0001, n = 17, 95% CI −0·218, −0·285), based on 26 species. Although Stahl (1967) does not give his original data, he reported that mammalian heart rate scales exactly as −0·25 (95% CI −0·23, −0·27). The slope for respiratory rate is −0·256 (P < 0·0001, n = 18, 95% CI −0·187, −0·320), based on 22 species. All of these exponents are almost exactly –1/4 and are statistically different from −1/3.

Figure 3.

Plot of (a) heart rates (Brody 1945) and (b) respiratory rates of mammals at rest (Calder 1968). The regression lines are fitted to the average of the logarithms for every 0·1 log unit interval of mass, but both the average (squares) and raw data (bars) are shown in the plots. Both slopes clearly include –1/4 and exclude −1/3, for heart rate the slope is −0·251 (P < 0·0001, n = 17, 95% CI −0·221, −0·281) and for respiratory rate −0·256 (P < 0·0001, n = 18, 95% CI −0·194, −0·318).

question 3: how do metabolic rates in other organisms scale? how do other biological rates and times scale?

Seemingly lost in the detailed discussions and analyses of mammalian metabolic rates are the extensive data for other allometric scaling relations. Metabolic rates have been measured and scaling exponents have been calculated for many groups of organisms in addition to mammals. The theory of West et al. (1997) predicts, and previous empirical studies suggest, that whole-organism metabolic rates in these other groups also scale as M3/4. In addition, extensions and applications of the theory predict that mass-specific metabolic rates and most other biological rates scale as M−1/4, and biological times, which are the inverse of rates, scale as M1/4. Although largely overlooked in recent work, the seminal treatments of biological allometry (McMahon & Bonner 1983; Peters 1983; Calder 1984; Schmidt-Nielsen 1984) had reached similar conclusions by the 1980s. Recent studies have shown that these allometric equations also apply to both unicellular algae and higher plants – including both gymnosperms and angiosperms (Enquist et al. 1998; West et al. 1999b; Enquist & Niklas 2001; Niklas & Enquist 2001; Enquist & Niklas 2002; Niklas & Enquist 2002). For example, both whole plant rates of biomass production and whole plant chlorophyll content scale as M3/4 (Niklas 1994). Further, intraspecific rates of production for 45 species of tropical trees scale with exponents indistinguishable from the predicted M3/4 scaling of metabolism (Enquist et al. 1999).

Methods

The four books by McMahon & Bonner (1983), Peters (1983), Calder (1984) and Schmidt-Nielsen (1984) in the 1980s still contain the most comprehensive treatments of biological allometry, including compilations of allometric equations for many different traits and taxonomic groups. We present meta-analyses of these data by compiling the allometric scaling exponents in histograms and by calculating the average and standard error for each histogram. Data for whole organism and mass-specific biological rates are from Peters (1983), and for biological times are from Lindstedt & Calder (1981). We also present the results of a recent compilation of rates of annual biomass production for numerous groups of plants and animals as compiled by Ernest et al. (2003).

Further, we reanalyse data on whole plant xylem flow from Enquist et al. (1998). Xylem flow is directly related to plant metabolic rate due to the stoichiometry of photosynthesis and respiration. When these data were collected (in litres of fluid transported vertically through the plant per day), xylem flux was measured in relation to stem diameter. To facilitate comparison with allometric equations for animals, we converted stem diameter, D (in cm), to above-ground plant mass, M (in g), using the empirical relationship M = 124D2·53, as outlined by Enquist & Niklas (2001). This relation of diameter to mass is well supported both theoretically and empirically (West et al. 1999b; Enquist 2002). We then divided the data into biomass bins, calculated an average for each bin, and performed a Reduced Major Axis (RMA) regression on the averaged data. Since the biomass is only an estimate, there are larger errors in the mass data than for the other plots in this paper. Furthermore, the errors for the masses are now comparable to the errors in measurement for the whole plant xylem flow, resulting in comparable errors for the variables on the x and y-axes of our plot. Consequently, reduced major axis (RMA) regression was used to fit these data (Niklas 1994).

Results

Exponents of whole-organism biological rates are plotted in Fig. 4. These data (see also Fig. 4.1 in Peters 1983) show a distinct mean and mode at 3/4 and not at 2/3 ( = 0·749 ± 0·007, SE). These data are for metabolic and other biological rates, e.g. feeding and defecation rates, and include values for a wide variety of organisms, including insects, crustaceans, mollusks, nematodes, cnidarians, porifera, algae, protists and all classes of vertebrates; they include freshwater, marine and terrestrial organisms.

Figure 4.

Histograms of the exponents of (a) biological rates (Peters 1983), (b) mass-specific biological rates (Peters 1983) and (c) biological times (Lindstedt & Calder 1981). At the top of each histogram, arrows are placed to identify the positions of the relevant third- and quarter-power exponents. Note that the peak of the histogram for biological rates is near 0·75, not 0·67 ( = 0·749 ± 0·007). Moreover, the histogram for mass-specific rates peaks near −0·25, not −0·33 ( = −0·247 ± 0·011), and the histogram for biological times peaks at 0·25, not 0·33 ( = 0·250 ± 0·011). All errors quoted here are the standard error from the mean for the distribution. Therefore, in all cases, the majority of biological rates and times exhibit quarter-power, not third-power, scaling.

There is considerable variation around 3/4. This is understandable because there are many uncontrolled sources of variation (e.g. sample size, range of variation in mass, experimental methods). Peters includes all studies that met minimal criteria, and we used all of his data.

Figure 4 shows a similar histogram for exponents of mass-specific metabolic rates and other related biological rates. Values clustered around –1/4 ( = −0·247 ± 0·011, SE). Figure 4 also contains a histogram for exponents of biological times, from muscle contractions to life spans. Values cluster closely around 1/4 ( = 0·250 ± 0·011, SE).

A summary of regression statistics from Ernest et al. (2003) for annual biomass production across multiple plant and animal taxa are listed in Table 1. The fitted exponents for plants, mammals, birds and fish are statistically indistinguishable from 3/4 and, apart from birds, have 95% CI that exclude 2/3.

Figure 5 plots xylem flow rate as a function of plant mass. The RMA regression line fitted to the binned data gives an exponent of 0·736 (P < 0·0001, n = 31, 95% CI 0·647, 0·825). The regression fitted to the entire unbinned data set gives a similar exponent of 0·735 (P < 0·0001, n = 69, 95% CI 0·682, 0·788). The exponent for the binned data has confidence intervals that include both 3/4 and 2/3, while that for the unbinned data includes only 3/4.

Figure 5.

Plot of maximum reported xylem flux rates (litres of fluid transported vertically through a plant stem per day) for plants from Enquist et al. (1998). The RMA regression line is fitted to the average of the logarithm for every 0·1 log unit interval of plant biomass, but both the average (squares) and raw data (bars) are shown in the plot. The slope is 0·736 (P < 0·0001, n = 31, 95% CI 0·647, 0·825).

Discussion

The results shown above raise the question: How is it that two recent studies reach the conclusion that mammalian BMR scales closer to M2/3 than to M3/4? This is especially puzzling because both of these studies and our analyses use much of the same data, including data compiled by Heusner (1991). The discrepancies in the exponent for mammalian BMR obviously depend on the methods of analysis. We now address these issues.

Two issues are particularly relevant. The first is whether the data points can be considered statistically independent, because the species differ in phylogenetic relatedness and closely related species tend to be more similar in body size, metabolic rate and most other biological attributes (Harvey & Pagel 1991). The second issue is that the available data for mammalian BMR are overly weighted towards species of small size. Binning the data according to intervals of logarithmic mass as described above is a reasonable but perhaps not ideal method for addressing both of these problems. By definition, it gives each size class equal weight. This prevents any size class from having an undue effect on the value of b. Moreover, because closely related species are almost always similar in size, it also prevents phylogenetic relatedness from having an undue influence. The effect of size on a function such as metabolic rate is best resolved by comparisons among species that differ in mass by several orders of magnitude, which means that the species compared are almost always distantly related.

Both of these issues arise in the recent work by Dodds et al. (2001) and White & Seymour (2003). Dodds et al. (2001) ignore phylogeny, even to the point of combining passerines and non-passerines to calculate a single allometric equation for all birds. In this case, there is an a priori basis, supported by phylogenetic analyses, for subdividing the data into two groups of birds (Garland & Ives 2000). The passerines, which constitute about half of existing bird species, are a monophyletic lineage that resulted from an extensive and separate radiation during the Tertiary (Garland & Ives 2000). Additionally, since the work of Lasiewski & Dawson (1967) in the 1960s, physiologists have recognized that when analysed separately, the two groups have very similar exponents (e.g. 0·72–0·75). The normalization constant, however, is higher for passerines than non-passerines (Lasiewski & Dawson 1967). Since the majority of passerines are smaller than non-passerines, the effect of combining the two groups is to reduce the apparent value of the exponent. The higher normalization constant for passerines is probably due in part to their slightly but consistently higher body temperatures. White & Seymour (2003) addressed the issue of phylogeny by calculating average values of the logarithms of mammalian body size and BMR for each taxonomic level: species, genus, family and order, and then fitted regression equations for each level. This is questionable for several reasons, including greatly reducing the sample size (from 619 data points (590 species after subspecies are removed and all scientific names are standardized) to 17 orders) and total range of variation in mass (by about an order of magnitude). The latter practice artefactually reduces the calculated value of the OLS regression slope, and hence underestimates the exponent (Pagel & Harvey 1988; Harvey & Pagel 1991).

Dodds et al. (2001) recognized there was a preponderance of data for small mammals and a curvilinearity across the entire body size range shown in our Fig. 1. They addressed this issue by calculating regression equations after progressively eliminating data for all species above some threshold body size. As the size threshold was reduced, they found a systematic decrease in the exponent, with an apparent break at M ∼ 10 kg and b ∼ 2/3 below this threshold. For M > 10 kg the CI included 3/4, and for M < 10 kg the CI did not include 3/4 and closely approached 2/3. White & Seymour's (2003) compilation, while quite accurate and extensive, does not contain some of the data available for the largest mammals. Consequently, their data set and analysis are even more strongly biased by the values for small mammals.

The original paper by West et al. (1997), which derives a model for the mammalian arterial system, predicts that smaller mammals should show consistent deviations in the direction of higher metabolic rates than expected from M3/4 scaling. Thus, metabolic scaling relationships are predicted to show a slight curvilinearity at the smallest size range. Therefore, fitting a regression through an allometric metabolic rate data set that samples a disproportionate number of small mammals will artificially give a slightly shallower slope. Prior to Dodds et al. (2001), Bartels (1982) found that above a threshold of 260 g, BMR data was best fit with an exponent of 0·76, and that below this threshold, the exponent was less than 2/3 or 3/4. Additionally, Calder (1984) noted that the smallest birds (hummingbirds) and mammals (shrews) have BMRs that are consistently above the predictions from allometry. Both Dodds et al. (2001) and White & Seymour (2003) ignore this prediction of the West et al. model. Ironically, the apparent deviation from 3/4 for small mass is therefore supportive of the West et al. (1997) model.

In addition to these statistical issues, White & Seymour (2003) use two biological arguments to adjust or exclude data. First, as shown in Gillooly et al. (2001), variation in body temperature may cause significant variation in BMR. White & Seymour (2003) find a weak but significant correlation between body temperature and size in mammals:

Tb = 35·8 + 0·21 log M.(eqn 2)

They corrected their BMR data to a constant body temperature using a Q10 factor. Second, White & Seymour (2003) eliminated data for entire taxonomic groups (artiodactyls, macropodid marsupials, lagomorphs and shrews) because these data may not meet the strict criteria required for BMR. After using these two procedures, they found that the temperature-adjusted BMR for the remaining species or orders scaled approximately as M2/3.

We can explicitly calculate the influence of body temperature on the scaling exponent. Substituting equation 2 into a Q10 factor, we derive that

bmeasured = bactual + 0·02,

where bmeasured is the value of b that is measured when no correction has been made for temperature. Note that this agrees exactly with the difference between 0·69 and 0·67 shown in Fig. 2(a)–(b) in White & Seymour (2003). Since the difference between exponents of 2/3 and 3/4 is 0·08, variation in body temperature among mammals must play a minor role in determining whether the exponent is 2/3 or 3/4. Additionally, by excluding certain taxa from their analysis, White & Seymour (2003) eliminate most of the smallest and largest mammals from their data set. This reduces the original 5·5 orders of magnitude variation in mass to 4·5 at the species level and to only 2·5 at the order level. Regardless of the problems of meeting the strict criteria for BMR, the exclusion of so much data clearly affects the ability to fit a power law that is representative of all mammals.

By comparing the analyses of Dodds et al. (2001) and White & Seymour (2003) with ours, it is obvious that values of b ranging from 2/3 to 3/4 can be obtained from data on mammalian BMR, depending on which data are included and how they are analysed. Our analyses and meta-analyses provide strong support for an exponent of 3/4. Theoretical work also supports this value. Detailed mechanistic models of mammal and plant vascular systems both predict this scaling (West et al. 1997, 1999a; Banavar et al. 1999; Banavar et al. 2002). This is noteworthy because of the major differences between the mammal and plant systems: pulsatile vs smooth flow, and a few large tubes branching into multiple smaller ones vs a constant number of microcapillary tubes diverging in bundles at branch points. Conversely, there are no dynamic, mechanistic models to explain why the exponent should be 2/3 in all organisms. Historically, Euclidean 2/3 scaling was expected due to surface area to volume relations. A physical argument is that endothermic mammals and birds maintain a constant body temperature by varying metabolic heat production to match heat loss to the environment (see Bergmann 1847 and discussion in Schmidt-Nielsen 1972). If heat dissipation is some simple function of skin surface area, A (i.e. emissivity and conductivity are assumed not to change with size), one might expect that B ∝ A ∝ M2/3. This argument lost most of its support, however, when research on endotherms showed that thermal balance is maintained by actively regulating heat exchange through changes in posture, fur and feather insulation, blood flow to peripheral tissues, and through evaporative cooling by sweating and panting, e.g. see McNab (2002).

The idea that biological allometries scale with quarter powers of body mass now rests on a strong theoretical and empirical foundation. Long before the recent surge of renewed interest in allometry, it was well established that the scaling exponents are much closer to quarters than to thirds. The extensive data compiled here, along with the new analyses, provide still further support. The evidence for quarter-power scaling is based not only on mammalian BMR, but also on a wide variety of biological rates and times in a multitude of organisms, from microbes to plants to mammals.

Peters (1983) summarized this when he wrote, ‘The surface law has a number of disadvantages when used to explain the M2/3 law. … Nevertheless, the simplicity of the surface law as an explanation proved so attractive that over a century of science was distorted by trying to fit observations to this inappropriate model (McMahon 1980).’ Let us not waste another century.

Acknowledgements

We are very grateful to Morgan Ernest for help with taxonomy. V.M.S., J.F.G., G.B.W., A.P.A. and J.H.B. are grateful for the support of the Thaw Charitable Trust, a Packard Interdisciplinary Science Grant, and an NSF Biocomplexity Grant. V.M.S., W.H.W., G.B.W., B.J.E. and J.H.B. are grateful for the support of LANL/LDRD Grant 20030050DR. W.H.W. is grateful for the support of NIH Grant DK36263, and B.J.E. is grateful for the support of an NSF CAREER award (NSF DEB-0133974). G.B.W. is also grateful for NSF Award PHY-0202180.

Note added in proof

Through communications from Prof. Ewald Weibel, we learned that there is a paper in press (Weibel, E. R., Bacigalupe, L. D., Schmitt, B., Hoppeler, H., Respiration Physiology, in press) in which a larger data set (35 mammalian species based on 57 estimates) for maximal metabolic rate is analysed. They report that maximal metabolic rate scales with an allometric exponent of 0·872 (P < 0·000 01, n = 35, 95% CI 0·813–0·932). They investigated the relationship between maximal metabolic rates and mitochondrial and capillary densities in the locomotor muscle system.

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