Support for a metapopulation structure among mammals


  • Editor: XL

R. J. van Aarde. E-mail:


  • 1The metapopulation metaphor is increasingly used to explain the spatial dynamics of animal populations. However, metapopulation structure is difficult to identify in long-lived species that are widely distributed in stochastic environments, where they can resist extinctions. The literature on mammals may not provide supporting evidence for classic metapopulation dynamics, which call for the availability of discrete habitat patches, asynchrony in local population dynamics, evidence for extinction and colonization processes, and dispersal between local populations.
  • 2Empirical evidence for metapopulation structure among mammals may exist when applying more lenient criteria. To meet these criteria, mammals should live in landscapes as discrete local breeding populations, and their demography should be asynchronous.
  • 3We examined the literature for empirical evidence in support of the classical criteria set by Hanski (1999), and for the more lenient subset of criteria proposed by Elmhagen & Angerbjörn (2001). We suggest circumstances where metapopulation theory could be important in understanding population processes in mammals of different body sizes.
  • 4The patchy distribution of large (>100 kg) mammals and dispersal often motivate inferences in support of a metapopulation structure. Published studies seldom address the full suite of classical criteria. However, studies on small mammals are more likely to record classic metapopulation criteria than those on large mammals. The slow turnover rate that is typical for medium-sized and large mammals apparently makes it difficult to identify a metapopulation structure during studies of short duration.
  • 5To identify a metapopulation structure, studies should combine the criteria set by Hanski (1999) and Elmhagen & Angerbjörn (2001). Mammals frequently live in fragmented landscapes, and processes involved in the maintenance of a metapopulation structure should be considered in conservation planning and management.


Claims for the existence of metapopulations are dominated by descriptions of population networks of insects (e.g. Leisnham & Jamieson, 2002; Massonnet, Simon & Weisser, 2002; Caudill, 2003; Thomas & Hanski, 2004; Rabasa, Gutiérrez & Escudero, 2007), birds (e.g. Esler, 2000; Inchausti & Weimerskirch, 2002; Githiru & Lens, 2004), reptiles (e.g. Semlitsch & Bodie, 2003; Rodrigues, 2005), amphibians (e.g. Alford & Richards, 1999; Marsh & Trenham, 2001; Smith & Green, 2005; Werner et al., 2007) and small mammals (e.g. Lima, Marquet & Jaksic, 1996; Lawes, Mealin & Piper, 2000). Few studies have addressed population networks in large mammals (>100 kg in body mass), and those that do apparently provide little support for metapopulation structures (Elmhagen & Angerbjörn, 2001).

Habitat fragmentation and loss often reduce the distributional ranges of large mammal species (e.g. Brashares, 2003; Cardillo et al., 2005). Anthropomorphic alterations of landscapes for agricultural or conservation purposes fragmented many populations; some may even be confined to a fraction of their former ranges (Ceballos & Ehrlich, 2002). This may reduce individual survival and increase extinction risk (Cardillo et al., 2006). The metapopulation concept caters for species that live in fragmented landscapes (Hanski, 1999). It focuses on populations that consist of local populations that exchange individuals through migration and dispersal, even when human mediated (Hanski & Simberloff, 1997; Akçakaya, Mills & Doncaster, 2007). It also integrates extinction, dispersal and colonization in patchy environments. It thus has appeal when designing conservation networks to overcome the effects of fragmentation (Önal & Briers, 2005).

The detection of population networks as metapopulations requires that (i) dispersal occurs between local populations; (ii) extinction and colonization take place; (iii) the dynamics of local populations are in asynchrony; and (iv) habitat patches support local breeding populations with colonizable vacant habitats (Hanski, 1999). Based on these criteria, Elmhagen & Angerbjörn (2001) found evidence for metapopulation dynamics among small mammals, but little support among large mammals. Based on Hanski's (1999) criteria, Elmhagen & Angerbjörn (2001) deduced two more lenient criteria for large mammals – first, breeding local populations should be discrete rather than inhabiting discrete habitat patches. Second, local populations should have dissimilar growth rates, i.e. some local populations may increase while, at the same time, others decrease. Such temporal fluctuations in growth rates imply demographic asynchrony among local populations (Elmhagen & Angerbjörn, 2001).

The use of the term ‘metapopulation’ has broadened substantially since it was proposed by Levins (1969). It now includes a variety of spatial population structures and definitions (see Hanski & Gilpin, 1991; Harrison, 1994; Pannell & Obbard, 2003; Akçakaya et al., 2007). However, this broadening of the original concept may detract from its meaning (Pannell & Obbard, 2003). As far as we are aware, only Hanski (1999) (for all species populations) and Elmhagen & Angerbjörn (2001) (for mammal species populations) recommended specific criteria that have to be met by a population for it to be classified as a metapopulation.

Here, we examine the empirical support for metapopulation dynamics among mammals. We determine the frequency of the application of the concept to mammal populations by searching literature published from 1991 to 2007, and recording proof for or against the classic criteria (Hanski, 1999) and the more lenient criteria proposed by Elmhagen & Angerbjörn (2001). We determine if body size influences the application of the criteria, and speculate on the value of the concept. Our study adds to the contribution of the review by Elmhagen & Angerbjörn (2001), and may assist in the formulation of conservation plans based on the restoration of spatial axes to regain spatial–temporal dynamics (Thomas & Kunin, 1999) that enhance persistence and overcome local impacts on other species (e.g. van Aarde & Jackson, 2007). We appreciate that the metapopulation concept is based on mathematical abstraction rather than empirical observation, but argue that this abstraction has value when it describes population processes that can be manipulated to enhance conservation initiatives (van Aarde, Jackson & Ferreira, 2006).


We collated empirical evidence for the existence of metapopulation dynamics among mammals by searching for relevant publications in the following electronic databases: Agricola, Biological Abstracts, Blackwell Synergy, Ecological Abstracts, Google Scholar (first 1000 ‘hits’ from, JSTOR, Science Direct, Scirus, Scopus, and Wildlife and Ecology Studies Worldwide. We based the search on the keywords ‘metapopulation and mammal*’. We recorded the number of studies that dealt with metapopulation dynamics in mammals for every year from 1991 to 2007. We included only papers in which the authors either described the metapopulation or stated that the population could potentially function as a metapopulation. We also included papers that did not explicitly test Hanski's (1999) or Elmhagen & Angerbjörn's (2001) criteria for metapopulations, but that casually may have deduced such dynamics. For instance, if authors stated that they classified their studied population based on evidence using the definition of Hanski & Gilpin (1991), which defines a metapopulation as ‘a set of local populations which interact via individuals moving among populations’, we assumed that the criteria of dispersal, discrete habitat patches or discrete local populations were met. We then recorded the specific criteria used by authors to infer a metapopulation structure for a species. For populations assessed more than once, we used the most recent publications. We distinguished among studies based on the body weight of the species that were studied and noted whether the apparent metapopulation existed in a natural, or ‘intact’ landscape (e.g. rocky cliffs) or in an anthropomorphically altered, or ‘disturbed’ landscape (e.g. artificially fragmented forests).

For each study, we recorded evidence for the populations meeting the criteria set by Hanski (1999) or the subset of criteria proposed by Elmhagen & Angerbjörn (2001). We noted whether the authors (i) found evidence, (ii) found no evidence, (iii) did not asses the specific criteria, and (iv) stated or assumed that a condition could be fulfilled, but did not provide supportive evidence. We then recorded the number of criteria used in each study to describe metapopulations. Furthermore, we noted the incidence at which specific criteria were used to describe metapopulations.

We distinguished between small mammals (≤5 kg), medium-sized mammals (>5 ≤ 100 kg) and large mammals (>100 kg), and used contingency table analyses to test for the influence of body size on the frequencies at which criteria were met, as well as for the influence of the type of landscape in which the mammals were studied. Statistical significance was set at α = 0.05.


The number of publications we found on metapopulation dynamics in mammals between 1991 and 2007 ranged from one to nine per year. In total, we included 63 studies, representing 75 species. Studies by Lima et al. (1996) on five and McShea et al. (2003) on nine species of small mammals were included as single studies and analysed as each representing one species, as the authors did not consider metapopulation criteria separately for every species. Conversely, the study by Gerlach & Hoeck (2001) was included and analysed as two studies, as the authors considered metapopulation criteria separately for two species. The studies included mammals ranging in body size from 0.002 to 5000 kg (see Appendix), and size classes were evenly distributed across intact and disturbed habitats (χ2 = 5.12, d.f. = 2, P = 0.077). The three studies on mammals >500 kg took place in landscapes fragmented by humans.

Not all the studies met the criteria recommended by Hanski (1999). In 90% of them (n = 57), dispersal was recorded between local populations, 16 (25%) experienced extinction and colonization events, while 33 (52%) exhibited asynchrony in population dynamics. Thirty (48%) occurred as breeding local populations in discrete habitat patches, with additional vacant habitats that could be colonized (Fig. 1). One of the criteria recommended by Elmhagen & Angerbjörn (2001) was met in 84% (n = 53) of studies; species occurred as discrete breeding local populations. Thirty-three (52%) exhibited asynchrony in dynamics (Fig. 1). For 32% (n = 20) of studies, only one of Hanski's (1999) criteria was used to describe a metapopulation structure, while 46% (n = 29) of studies met one or the other of Elmhagen & Angerbjörn's (2001) two criteria (Fig. 2). Both the criteria of Elmhagen & Angerbjörn (2001) were noted for 41% (n = 26) of the studies, while 66% (n = 42) met more than one of Hanski's (1999) criteria (Fig. 2).

Figure 1.

The percentage of (a) small, (b) medium-sized and (c) large mammal species populations, in which the criteria of Hanski (1999) and Elmhagen & Angerbjörn (2001) were used to describe metapopulation dynamics in mammals. Open bars indicate the classic criteria of Hanski (1999), shaded bars indicate the more lenient criteria described by Elmhagen & Angerbjörn (2001). Sample sizes are numbers of studies.

Figure 2.

The number of criteria that researchers applied to describe (a) small, (b) medium-sized and (c) large mammal species populations as metapopulations based on papers published from 1991 to 2007. Open bars indicate the classic criteria of Hanski (1999), shaded bars indicate the more lenient criteria described by Elmhagen & Angerbjörn (2001). Sample sizes are numbers of studies.

Body size influenced the patterns noted above. For small (≤5 kg), medium (>5 ≤ 100 kg) and large (>100) species, dispersal was the condition most frequently assessed (Fig. 1). Dispersal between local populations was also assessed at similar frequencies among body size classes (χ2 = 0.396, d.f. = 2, P = 0.821). Population turnover was recorded for 14 of 30 studies on small mammals, but for only one of 15 on medium sized and one of 18 on large mammal species. The frequency of reporting asynchrony in population dynamics differed with body size (χ2 = 8.476, d.f. = 2, P = 0.014). The reporting of incidences of habitat patches that supported breeding local populations did not differ with body size (χ2 = 5.670, d.f. = 2, P = 0.059) (Table 1). The occurrence of discrete breeding local populations was similar for small, medium-sized and large mammals (χ2 = 0.095, d.f. = 2, P = 0.953) (Table 2).

Table 1.  An assessment of the classical criteria of metapopulations (Hanski, 1999) reported in studies on small (≤5 kg; n = 30), medium (>5 ≤ 100 kg; n = 15) and large (>100 kg; n = 18) mammal species (total n = 63)
Metapopulation criteria Small mammalsMedium mammalsLarge mammals
Individual dispersalYes261417
Not assessed100
Population turnoverYes1411
Not assessed161417
Asynchrony in dynamicsYes18312
Not assessed12126
Habitat patches with breeding sub-populationsYes1956
Not assessed111012
Table 2.  An assessment of the more lenient criteria of metapopulations (Elmhagen & Angerbjörn, 2001) reported in studies on small (≤5 kg; n = 30), medium (>5 ≤100 kg; n = 15) and large (>100 kg; n = 18) mammal species (total n = 63)
Metapopulation criteria Small mammalsMedium mammalsLarge mammals
Breeding sub-populations are discreteYes251415
Not assessed513
Asynchrony in dynamicsYes18312
Not assessed12126

In most (60%) of the 63 studies published on metapopulation dynamics, authors stated that they evaluated criteria before classifying the population as a metapopulation, while 15% (n = 9) classified populations as metapopulations, but did not evaluate any criteria. In about 16% (n = 10) of studies, authors suggested that the studied population would function as a metapopulation if suitable conservation measures were put into place, while a further 7% (n = 4) of studies dealt with artificially created metapopulations where metapopulation processes and criteria were mimicked by management strategies. In two studies (3%), the population used to function as a metapopulation, but did not anymore. In one case, the studied population was found not to be a metapopulation. For small mammals, 9 out of 30 (30%) studies mentioned that metapopulation processes could contribute to the conservation of the studied species populations, while for large and medium-sized mammals, 22 out of 33 (67%) studies invoked metapopulation processes for conservation purposes.


Metapopulations are not always easy to identify (Hanski & Simberloff, 1997; Thomas & Kunin, 1999). Our analysis suggests that the use of the concept is not always supported by empirical information that may meet the criteria of Hanski (1999), or even the more lenient subset of criteria proposed by Elmhagen & Angerbjörn (2001). Most of the 63 studies that we assessed provide some evidence for a metapopulation structure, and nearly all authors concluded that the population they studied functioned as a metapopulation. However, much of the evidence for metapopulations stems from the inconsistent application of the concept and the use of a range of definitions that ignores some of the original criteria. For instance, in only one (Hayward et al., 2004) of the 29 studies published since 2001 is it stated explicitly that the criteria recommended by Elmhagen & Angerbjörn (2001) were evaluated.

The criteria of Elmhagen & Angerbjörn (2001) seem easier to apply than those of Hanski (1999). For example, in most (84%) of the 63 studies that we reviewed, the species comprised discrete breeding local populations, and thus met one of the two criteria set by Elmhagen & Angerbjörn (2001), while in only half (48%), the studied species inhabited discrete habitat patches with additional vacant habitats that can be colonized, as expected by one of the four criteria of Hanski (1999). However, most (83%) of the studies that recognized discrete habitat patches, as recommended by Hanski (1999), or discrete breeding local populations as recommended by Elmhagen & Angerbjörn (2001), used dispersal to deduce metapopulation dynamics. Therefore, no matter the criteria, where species illustrate dispersal, studies deduced metapopulation structures.

Our analysis furthermore suggests that the size of mammals influences the criteria that may be used to support metapopulation dynamics. For instance, for small mammal species (≤5 kg), the criteria of Hanski (1999) were met with the same frequency as those of Elmhagen & Angerbjörn (2001). Small mammals were also more likely to adhere to the full set of criteria proposed by Hanski (1999). For instance, extinction and colonization events were recorded in 46% of small mammal species populations compared with only 7 and 6% in medium-sized and large mammals respectively.

Case studies that support the classical metapopulation structure are rare (Elmhagen & Angerbjörn, 2001). This is also supported by our review. Only five of 75 species populations adhered to classical metapopulation criteria – these are all small mammals and comprise the four-eyed opossum Philander opossum, American pika Ochotona princeps, black-tailed prairie dog Cynomys ludovicianus, field vole Microtus agrestis and the round-tailed muskrat Neofiber alleni (Adler & Seamon, 1996; Moilanen, Hanski & Smith, 1998; Roach et al., 2001; Banks et al., 2004; Schooley & Branch, 2007). Few studies thus provide support for the full set of criteria for the classical metapopulation. Meeting these criteria depends on case-specific spatial conditions to which populations will respond. From the review of Krohne (1997), it is apparent that fragmentation, dispersal barriers and dispersal corridors are all species population specific, and that species' responses to these depend on body size, habitat, physiological responses to stressful environments and social factors. We therefore agree with Clinchy, Haydon & Smith (2002) that evidence of metapopulation processes rather than spatial occupancy should be used to provide evidence of metapopulation dynamics.

For studies on small mammals, we propose that the full complement of metapopulation criteria (Hanski, 1999) can be applied to yield new perspectives on population regulation. Metapopulation processes could also be used to parameterize models that emphasize small mammal characteristics (see Lambin et al., 2004). Metapopulation processes can also be incorporated into management and conservation paradigms. For instance, McShea et al. (2003) suggest that a timber harvest management paradigm based on metapopulation processes would conserve small mammal species populations more effectively than a traditional approach that only focused on the proportion of available habitat.

Our review suggests that the application of the metapopulation concept differs between small and other-sized mammals, but is similar for medium and large mammals. Authors consider dispersal between discrete local populations of large mammals as the key condition for a metapopulation structure and tend to ignore the other criteria. For instance, in 31 of the 33 studies on large mammal populations, all criteria except dispersal are ignored by authors, labelling their studied population as a metapopulation. The limitations in evaluating the other criteria may induce this bias. Criteria associated with extinction and recolonization events may not be used, because the time span of these events usually exceeds that of most studies, possibly due to the relatively long generation times and slow reproductive rates of large mammals (Murphy, Freas & Weiss, 1990). It may therefore prove futile for studies on larger mammals to focus on population turnover as a condition to be met for metapopulation dynamics. Even so, our results suggest that a metapopulation structure can exist in mammals, but that the longevity and slow turnover typical of medium- and large-sized mammals may make it difficult to find support for the full set of classical criteria for a metapopulation structure. Despite this detraction, the metapopulation concept can be applied to large mammal species populations.

Our review suggests that most (31 of 33 studies, 94%) medium and large mammal species populations that occurred as discrete breeding local populations also dispersed between local populations. Furthermore, the dynamics of nearly half (15 of 31, 48%) of these populations were asynchronous. Such asynchrony could reflect on habitat heterogeneity, lack of dispersal between local populations, variation in community processes and trophic interactions, and environmental variation that can induce source–sink dynamics (Pulliam, 1988; Bjørnstad, Ims & Lambin, 1999). Alternatively, synchrony in population dynamics can result from high dispersal rates or correlated changes in environmental conditions (Ranta, Kaitala & Lundberg, 1998).

Dispersal alone may not be a good indicator of metapopulation dynamics. We propose that both dispersal, the focus of much of the literature we reviewed, and asynchrony in dynamics between discrete local populations, need to be included in the evaluation. Because turnover is difficult to record in medium to large mammals, the illustration of dispersal and asynchrony alone may serve as evidence for a metapopulation structure.

Determining the spatial structure of a population is essential when formulating conservation guidelines, because it presents a conceptual tool for dealing with the interactions between, within and among populations (Githiru & Lens, 2004). The application of metapopulation theory may be more important for large than small mammals for the simple reason that large mammals usually operate at spatial scales at which they are exposed to landscape fragmentation. Consequently, large mammals are more frequently exposed to human-induced disturbances than small mammals (Crooks, 2002; Cardillo et al., 2005), and are often restricted to national parks and wildlife reserves (e.g. Brashares, 2003).

Spatial population patterns maintain processes that have implications for persistence (Thomas & Hanski, 2004). Emphasis therefore should shift from observing spatial patterns to recording spatial processes (e.g. Thomas & Kunin, 1999; Hanski & Gaggiotti, 2004). We therefore suggest that metapopulation theory should be applied to populations of mammals when constructing conservation plans to ensure population persistence and to contribute to the forces that stabilize populations regionally.

Most (22 of 33, 67%) of the studies we included in our review, which explicitly deal with medium and large mammals, suggest that conservation will benefit from the inclusion of metapopulation processes. For instance, Singh & Kumara (2006) recognized that for a wide-ranging animal such as the Indian grey wolf Canis lupus pallipes, sanctuaries could only protect one or two wolf packs. They suggest that the conservation of forest patches of varying sizes in a landscape matrix could facilitate the dispersal of wolf packs that then may become part of a large metapopulation. Similarly, Sweanor, Logan & Hornocker (2000) and Hellgren, Onorato & Skiles (2005) showed that cougars Puma concolor and black bears Ursus americanus persist if conservation initiatives are implemented on a regional scale. The most artificial application of the metapopulation concept in conservation comes from the advocacy that removing individuals from one isolated population mimics dispersal. Translocations of wild dog Lycanon pictus and black rhino Biceros dicornis from one conservation area to another in Africa (Amin et al., 2006; Akçakaya et al., 2007) serve as good examples.

We caution against implementing conservation strategies based on metapopulation dynamics if habitat discreteness, likelihood of dispersal and potential of asynchrony have not been evaluated. The application of metapopulation theory to cases or species that do not meet the criteria to exist as a metapopulation may lead to conservation actions that neglect important life histories, with consequences for species persistence (see Grimm, Reise & Strasser, 2003). For instance, the metapopulation concept can motivate the development of movement corridors without evidence that corridors would be used, or forestall extinction (Boitani et al., 2007). Such actions are expensive and could detract from efforts to protect particular populations that require specific refuges (Simberloff et al., 1992; Boitani et al., 2007). However, the correct and consistent application of metapopulation theory and the implementation of metapopulation processes in mammal populations may improve the persistence of mammals in fragmented habitats.


The study was supported through grants from the International Fund for Animal Welfare, the Peace Parks Foundation and the University of Pretoria. The preparation of the manuscript benefitted greatly from the contributions of two referees.


Table A1.  Studies in which mammals have been described as metapopulations or as possibly functioning as metapopulations
Species populationBody mass (kg)Fragmentation typeDispersalTurnoverAsynchronyDiscrete habitat patchesDiscrete breeding sub-populationsMetapopulation TypeReference
  • N.A., not assessed.

  • The empirical support for this classification or lack thereof, as described in the studies, is shown for each species.

  • *

    Metapopulation described as ‘type C’ from Krohne (1997).

Bank vole Clethrionomys glareolus0.002–0.003AnthropogenicYesYesYesN.A.YesSource-sinkvan Apeldoorn et al. (1992)
Euro Macropus robustus90AnthropogenicYesN.A.N.A.YesYesNot describedArnold et al. (1993)
Greater glider Petauroides volans AnthropogenicYesYesN.A.YesN.A.ModelledPossingham et al. (1994)
Pine vole Microtus duodecimcostatus0.002–0.003NaturalYesYesPotentialN.A.YesSource–sinkParadis (1995)
Four-eyed opossum Philander opossum0.24–0.4NaturalYesYesYesYesYesBoorman–LevittAdler & Seamon (1996)
Leadbeater's possum Gymnobelideus leadbeateri0.12–0.16AnthropogenicPossibleYesN.A.YesYesNot describedLindenmayer & Possingham (1996)
Vancouver island marmots Marmota vancouverensis0.25NaturalYesN.A.N.A.YesYesNot describedBryant & Janz (1996)
Lower Keys marsh rabbit Sylvilagus palustris hefneri2.5–3NaturalYesYesYesN.A.YesNot describedForys & Humphrey (1996)
Leaf-eared mouse Phyllotis darwini; olive grass mouse Akodon olivaceus; elegant fat-tailed opossum Thylamys elegans; Degu Octodon degus; long-tailed pygmy rice rat Oligoryzomys longicaudatus0.005–0.01NaturalN.A.YesN.A.N.A.YesNot describedLima et al. (1996)
White-tailed deer Odocoileus virginianus300–600AnthropogenicYesN.A.N.A.YesYesNot describedSeagle & Close (1996)
Leaf-eared mouse Phyllotis darwini0.007–0.01AnthropogenicPossibleYesYesN.A.YesPartially coupledTorres-Contreras et al. (1997)
Polar bear Ursus maritimus300–600NaturalYesN.A.N.A.N.A.YesNot describedFerguson et al. (1998)
Iberian lynx Lynx pardinus13–25AnthropogenicYesPotentialN.A.YesYesSource–sinkGaona, Ferreras & Delibes (1998)
Puku Kobus vardoni74–77NaturalYesN.A.N.A.YesYesNot describedGoldspink et al. (1998)
American pika Ochotona princeps0.5–1.0NaturalYesYesYesYesYesClassicalMoilanen et al. (1998)
Woodland caribou Rangifer tarandus caribou170–300AnthropogenicPossibleN.A.YesN.A.YesNot describedRettie & Messier (1998)
Tiger Panthera tigris205–227AnthropogenicPossibleN.A.N.A.N.A.YesNot describedSmith, Ahearn & McDougal (1998)
Harbour seal Phoca vitulina∼130NaturalPossibleN.A.PotentialN.A.YesNot describedSwinton et al. (1998)
White-footed mouse Peromyscus leucopus0.023AnthropogenicYesN.A.YesYesYesNot described*Krohne & Hoch (1999)
Greater glider Petauroides volans1.6–1.9AnthropogenicPossibleN.A.N.A.N.A.YesNot describedMcCarthy & Lindenmayer (1999)
Nubian ibex Capra ibex nubiana∼50NaturalYesN.A.N.A.N.A.YesNot describedShkedy & Saltz (2000)
Yellow-necked mice Apodemus flavicollis0.016–0.032AnthropogenicYesN.A.N.A.YesN.A.PatchySzacki (1999)
Long-furred woolly mouse opossum Micoureus demerarae0.13AnthropogenicYesN.A.N.A.YesYesNot describedPires & Fernandez (1999)
San Joaquin kit foxes Vulpes macrotus mutica7–8AnthropogenicYesN.A.YesN.A.YesNot describedKoopman, Cypher & Scrivner (2000)
Samango monkey Ceropithecus mitis liabiatus7–9AnthropogenicNoN.A.N.A.N.A.YesTransient non-equilibriumLawes et al. (2000)
Tree hyrax Dendrohyrax arboreus∼3AnthropogenicYesN.A.N.A.YesYesMainland–islandLawes et al. (2000)
Blue duiker Cephalophus monticola4–5AnthropogenicYesN.A.N.A.YesYesMainland–islandLawes et al. (2000)
Bighorn sheep Ovis Canadensis170–302NaturalYesN.A.YesYesYesNot describedSinger, Bleich & Gudorf (2000)
Cougar Puma concolor∼75AnthropogenicYesN.A.N.A.N.A.YesNot describedSweanor et al. (2000)
Silvery gibbon Hylobates moloch∼8AnthropogenicPossibleN.A.N.A.N.A.YesNot describedAndayani et al. (2001)
Mountain pygmy possum Burramys parvus0.045NaturalYesN.A.YesN.A.YesNot describedBroome (2001)
Artic fox Alopex lagopus3.1–3.8AnthropogenicYesN.A.YesYesYesNot describedElmhagen & Angerbjörn (2001)
Rock hyrax Heterohyrax brucei∼3NaturalYesN.A.PotentialYesYesNot describedGerlach & Hoeck (2001)
Rock hyrax Procavia johnstoni∼3NaturalNoN.A.PotentialYesYesNot describedGerlach & Hoeck (2001)
Black-tailed prairie dog Cynomys ludovicianus0.7–1.5AnthropogenicYesYesPotentialPotentialYesNot describedRoach et al. (2001)
Grey seal Halichoerus grypus200–350NaturalYesYesYesYesYesNot describedGaggiotti et al. (2002)
Florida panther Puma concolor∼75AnthropogenicYesN.A.N.A.N.A.N.A.Not describedMaehr et al. (2002)
Spanish ibex Capra pyrenaica∼50AnthropogenicPossibleN.A.N.A.N.A.YesNot describedPérez et al. (2002)
Steller sea lion Eumetopias jubatus∼300NaturalYesN.A.YesN.A.YesNot describedRuam-Suryan et al. (2002)
Kodkod Oncifelis guigna11–14AnthropogenicYesN.A.N.A.N.A.YesMainland–islandAcosta-Jamett et al. (2003)
White-footed mouse Peromyscus leucopus; deer mouse Peromyscus maniculatus; northern short-tailed shrew Blarina brevicauda; Eastern chipmunk Tamias striatus; Southern red-backed vole Clethrionomys gapperi; woodland jumping mouse Napaeozapus insignis; smoky shrew Sorex fumeus; masked shrew Sorex cinereus; pygmy shrew Sorex hoyi0.01–0.05NaturalYesYesYesYesN.A.Not describedMcShea et al. (2003)
Field vole Microtus agrestis0.01–0.03NaturalPossibleYesPotentialN.A.YesNot describedBanks et al. (2004)
Water vole Arvicola aphibius0.16–0.35NaturalYesYesN.A.YesYesNot describedLambin et al. (2004)
Indus river dolphin Platanista minor170–301NaturalNoN.A.N.A.N.A.YesNot describedGachal & Slater, 2004
Tundra vole Microtus oeconomus∼0.05Experimental populationYesN.AYesYesYesNot describedIms & Andreassen (2005)
Amur tiger Panthera tigris altaica215–270AnthropogenicYesN.A.YesN.A.N.A.Not describedCarroll & Miquelle (2006)
Quokka Setonix brachyurus2.5–5.0AnthropogenicNoYesYesYesYesNot describedHayward et al. (2004)
European bison Bison bonasus450–1000AnthropogenicPossibleN.A.PotentialYesYesNot describedPerzanowski, Olech & Kozak (2004)
Ethiopian wolf Canis simensis∼20NaturalYesN.A.PotentialYesYesNot describedSillero-Zubiri et al. (2004)
Fisher Martes pennanti2.1–7.0NaturalPossibleN.A.N.A.N.A.N.A.Not describedWisely et al. (2004)
Black bear Ursus americanus170–303NaturalYesN.A.PotentialYesYesMainland–islandHellgren et al. (2005)
Brown bear Ursus arctos130–700AnthropogenicYesN.A.N.A.N.A.YesNot describedPreatoni et al. (2005)
Gaint panda Ailuropoda melanoleuca100–115AnthropogenicPossibleN.A.N.A.N.A.YesNot describedRan et al. (2005)
Ili pika Ochotona iliensis0.5–1.0NaturalNoN.A.N.A.N.A.N.A.Not describedLi & Smith (2005)
Amur tiger Panthera tigris altaica215–270AnthropogenicYesN.A.YesN.A.N.A.Not describedCarroll & Miquelle (2006)
Black rhino Diceros bicornis∼1000AnthropogenicYesN.A.PotentialYesYesNot describedAmin et al. (2006)
Mountain caribou Rangifer tarandus caribou170–300AnthropogenicYesN.A.YesN.A.YesNot describedApps & McLellan (2006)
Indian gray wolf Canis lupus pallipes18–27AnthropogenicYesN.A.N.A.N.A.YesNot describedSingh & Kumara (2006)
Mountain vizcacha Lagidium peruanum∼3NaturalPossibleN.A.N.A.YesYesNot describedWerner, Ledesma & Rodrigo (2006)
European hare Lepus europaeus2.5–6.5AnthropogenicYesN.A.PotentialN.A.N.A.Not describedBray et al. (2007)
Wild dog Lycanon pictus24–28AnthropogenicYesN.A.PotentialYesYesNot describedAkçakaya et al. (2007)
Peccary Tayassu pecari20–40AnthropogenicPossibleN.A.N.A.N.A.YesNot describedMendes Pontes & Chivers (2007)
Elephant Loxodonta africana5500–6000AnthropogenicYesN.A.YesN.A.N.A.Source–sinkvan Aarde & Jackson (2007)
Round-tailed muskrat Neofiber alleni0.2–0.4NaturalYesYesPotentialYesYesSource–sinkSchooley & Branch (2007)