SEARCH

SEARCH BY CITATION

Keywords:

  • Crocuta crocuta;
  • garbage;
  • human disturbance;
  • human-carnivore conflict;
  • Masai Mara;
  • movements

Abstract

  1. Top of page
  2. AbstractRésumé
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Although the use of anthropogenic food sources by carnivores is well documented, few studies have investigated the potential for these sites to influence the movements of livestock predators. We capitalized on a natural experiment in which a refuse pit, utilized by a group of intensively monitored spotted hyenas (Crocuta crocuta) in the Masai Mara National Reserve, Kenya, was closed midway through monitoring efforts. We compared hyena space use patterns before and after closure, while controlling for other variables, to investigate the influence of the pit on home range size, core area size and location, and the proximity of hyenas to dens and the refuse pit itself. We also investigated the influence of prey abundance and the social ranks of individual hyenas on variation in frequency of pit utilization. We found home range size to increase and core area size to decrease following pit closure. Space use was clearly influenced by the pit, as the group core area included the refuse site only while it was in operation, and hyenas were found closer to the pit before than after its closure. The most common rank group observed feeding at the pit were low-ranking females, and regular pit users were more likely to be found near the pit during times of relative prey scarcity. We discuss the potential of human refuse at pastoral villages to increase livestock losses to hyenas.

Résumé

Bien que la consommation de produits alimentaires d’origine humaine par les carnivores soit bien documentée, peu d’études se sont intéressées à la possibilité qu’ont les sites d’origine d’influencer les déplacements des prédateurs du bétail. Nous avons tiré parti d’une expérience naturelle où un trou à ordures utilisé par un groupe d’hyènes tachetées (Crocuta crocuta) suivi de près dans la Réserve Nationale de Masai Mara, au Kenya, fut fermé au beau milieu de nos efforts de monitoring. Nous avons comparé les schémas d’utilisation de l’espace par les hyènes avant et après la fermeture, tout en comparant d’autres variables, pour connaître l’influence du trou sur la taille du domaine vital, la taille et l’emplacement de sa zone centrale et la proximité des hyènes avec les terriers et avec le trou lui-même. Nous avons aussi étudié l’influence de l’abondance des proies et du rang social des hyènes sur les variations de fréquence d’utilisation du trou. Nous avons découvert que la taille du domaine vital augmentait et celle de la zone centrale diminuait suite à la fermeture du trou. L’utilisation de l’espace était clairement influencée par le trou étant donné que la zone centrale du groupe n’a inclus le trou à ordures que tant qu’il a été ouvert et que les hyènes se trouvaient plus près du trou avant sa fermeture qu’après. La partie du groupe que l’on observait le plus souvent en train de se nourrir dans le trou était composé des femelles de rang inférieur, et les utilisateurs réguliers étaient plus susceptibles de se trouver près du trou lors de périodes où les proies étaient relativement rares. Nous discutons du fait qu’il est possible que les déchets des gens dans les villages pastoraux augmentent les pertes de bétail causées par les hyènes.


Introduction

  1. Top of page
  2. AbstractRésumé
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Patterns of space use by large carnivores are determined by a multitude of factors including availability of water, den sites, cover from predation or climate (Ewer, 1973) and competition (Durant, 1998), but are often most closely associated with the distribution and abundance of prey (Mills & Knowlton, 1991; Hofer & East, 1993; Spong, 2002). Numerous species utilize human-provided food sources as components of their diet (e.g. Canis lupusFuller & Keith, 1980; Vulpes vulpes –Doncaster, Dickman & Macdonald, 1990; Ursus americanus –Herrero, 1983; U. arctos –Knight & Eberhardt, 1985; Crocuta crocuta –Mills & Hofer, 1998). It has been shown these anthropogenic resources influence carnivore movements (Craighead & Craighead, 1971; Ciucci et al., 1997), home range size (Blanchard & Knight, 1991; Hidalgo-Mihart et al., 2004), and population density (Fuller & Keith, 1980; Fedriani, Fuller & Sauvajot, 2001). Additionally, the presence of these resources may influence the frequency of human-carnivore conflict by increasing carnivore densities (Yom-Tov, Ashkenazi & Viner, 1995), or by shifting populations (Beckmann & Berger, 2003) or individuals (Lunn & Stirling, 1985; Knight, Blanchard & Eberhardt, 1988) toward human-dominated areas. Resulting conflicts may cause property damage (e.g. livestock), human injury, and increased carnivore mortality, with these areas acting as population sinks (Knight et al., 1988). As human population growth and habitat conversion proceed at increasing rates, human-carnivore conflict, particularly livestock depredation, threatens to impede large carnivore conservation efforts where carnivores share the landscape with humans. However, few studies have investigated the influence of human-provided food sources other than livestock on the movements and space use of potential livestock predators.

Seasonal variation in the use of refuse sites has been documented in a number of carnivores and is often associated with variation in prey availability and seasonal variation in nutritional requirements (Craighead & Craighead, 1971; Salvador & Abad, 1987; Lucherini & Crema, 1994). It is also likely that variable nutritional demands of different age/sex classes, and reduced competitive ability in social carnivores of low social rank, may result in variation in the use of these resources at the level of the individual. Identification of the animals most likely to utilize human-provided food sources may help to identify the existence of potential ‘problem individuals’ (see review in Linnell et al., 1999), and the factors that may lead to their destructive behaviour. However, few studies have investigated individual variation in the use of refuse sites by large carnivores (but see Lunn & Stirling, 1985 and Rogers et al., 1976).

Spotted hyenas (Crocuta crocuta Erxleben) are important predators of livestock throughout East Africa (Kruuk, 1981; Ogada et al., 2003; Kolowski & Holekamp, 2006). Although Crocuta feed primarily on freshly killed ungulates that they hunt themselves (Kruuk, 1972; Gasaway, Mossestad & Stander, 1991), hyenas are opportunistic foragers and efficient scavengers that have been observed to feed on a huge variety of food items including insects, birds, rodents and even garbage (Henschel & Skinner, 1990; Mills & Hofer, 1998; Cooper, Holekamp & Smale, 1999). It has been suggested that refuse and livestock carcasses at pastoral villages may influence the frequency of hyena visits to these areas and ultimately, livestock depredation rates (Mills & Hofer, 1998; Kolowski & Holekamp, 2006).

Our goal here was to document the influence of a single human refuse source on the space use patterns of adult hyenas, and to investigate the influence of hyena social rank and local prey abundance on variation in the use of this food source. We capitalized on a natural experiment in which a refuse site was closed midway through intensive monitoring of individual hyenas whose defended group territory contained the refuse site.

Materials and methods

  1. Top of page
  2. AbstractRésumé
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Study population and habitat characteristics

Our study was conducted from June 2001 through April 2004 in the Masai Mara National Reserve (hereafter the Reserve) in southwestern Kenya. The 1500 km2 Reserve consists primarily of rolling grassland and scattered bushland (predominantly Croton and Euclea species), with riparian forest along the major watercourses, and supports more than fifteen species of resident ungulates totalling approximately 50,000 animals (Broten & Said, 1995; Ottichilo et al., 2000). From August to October, the Reserve also supports large migratory herds of approximately 200,000–300,000 wildebeest (Connochaetes taurinus) and an additional 10,000–50,000 zebra (Equus burchelli;Broten & Said, 1995; Serneels & Lambin, 2001). Primarily because of its diversity and abundance of predators, as well as the seasonal influx of migratory ungulates, the Reserve is Kenya’s premier wildlife tourist attraction (Norton- Griffiths, 1995), and supports 24 permanent tourist camps and lodges (Walpole et al., 2003). Although many are located just outside the Reserve boundary, a small subset of lodges (∼20%) are located within the Reserve itself, and this study focuses on one of the latter.

Spotted hyenas live in social groups called clans, and clan members cooperatively defend a stable group territory. Each clan contains one to several matrilines of adult females and their offspring, as well as a variable number of adult immigrant males. Clans are rigidly structured by hierarchical rank relationships (Kruuk, 1972; Tilson & Hamilton, 1984; Frank, 1986) that determine priority of access to food, and all adult females are socially dominant to immigrant males (Kruuk, 1972; Smale, Frank & Holekamp, 1993). Subadult individuals of both sexes maintain their maternal ranks as long as they remain in the natal clan (Smale et al., 1993). Although females are generally philopatric (Frank, 1986), most natal males disperse between the ages of 2 and 5 years (Henschel & Skinner, 1987; Smale, Nunes & Holekamp, 1997; East & Hofer, 2001). Crocuta clans are fission–fusion societies in which individuals travel, rest and forage in subgroups that typically change in composition many times each day (Kruuk, 1972; Holekamp et al., 1997). Female Crocuta bear 1–2 (rarely 3) young in isolated natal dens (Holekamp, Smale & Szykman, 1996). Cubs are typically transferred to a communal den at 2–5 weeks of age where they reside for the next 7–8 months (Kruuk, 1972). The communal den represents the social center of each clan’s territory and most clan members visit it regularly.

We monitored individuals from a single clan (the Mara River clan) that defended a territory (31 km2) near the center of the Reserve (Fig. 1). The clan included 32–43 individuals (inline image = 8 adult females, inline image = 5 adult immigrant males), and each hyena was individually recognized by unique spot patterns. A single tourist lodge, which maintained an unfenced refuse pit approximately 300 m from the periphery of its grounds, was located near the northern boundary of the Mara River clan territory (Fig. 1). Garbage, mainly composed of food refuse from tourist and staff dining halls, was deposited daily into a circular earthen pit (diameter ∼8 m), usually between 9.00–10.00 hours. The pit was closed on 12 October 2002 and all garbage was removed from the site. In the following weeks the pit was filled with soil, and native shrubs and trees were planted.

image

Figure 1.  Territory of the Mara River hyena clan and its location within the Masai Mara National Reserve. Hatched lines represent ungulate prey sampling transects. The refuse pit (filled circle) and tourist lodge are also indicated

Download figure to PowerPoint

Data collection

We anaesthetized and radiocollared six adult female hyenas from the Mara River clan of variable social rank, and made attempts to locate each individual on a daily basis. On average, we collected fifteen telemetry locations per month for each collared hyena. The majority (∼78%) of radiotracking was conducted during the morning (05.30–09.00 hours) and evening (17.30–20.00 hours), but additional locations were collected during mid-day and throughout the night. Although few locations were collected during the middle of the night, both our primary monitoring periods were largely within the active period (18.00–09.00 hours) documented for Reserve hyenas (Kolowski & Holekamp, 2007). In addition to tracking efforts, we made regular visits to the refuse pit at all times of day; however, hyenas were only observed at the site when fresh refuse was present (i.e. late morning). During these observation sessions, we recorded the number and identity of hyenas present, as well as the presence of other species at the site.

Using tracking locations from five of the six monitored adult female hyenas (one female was not monitored after pit closure), we compared space use patterns before and after pit closure using the following variables: 95% fixed kernel home range size, 50% fixed kernel home range (core area) size, presence/absence of the refuse pit within the core area, and average hyena distance to the refuse pit. Home range size during the full 16-month preclosure period was strongly influenced by the consecutive use of communal dens separated from each other by as much as 6 km. We therefore limited the preclosure locations for this analysis to those collected in the 10 months prior to pit closure, when consecutive den locations were consistently only short distances apart. Throughout this 10-month period, and the entire postclosure period, the communal den was always located in the northeast portion of the territory, and therefore, the influence of den shifts on space use comparisons was effectively removed. Because space use of female hyenas is dependent on whether they have cubs residing at the communal den (Boydston et al., 2003), we categorized all preclosure locations for each female with respect to whether or not she had den-dwelling cubs. We then randomly subsampled locations collected in the 19-month postclosure period for each female to equalize the number of locations collected before and after closure with and without den-dwelling cubs (minimum of 20 locations per female pre- and postclosure). Because female space use is even further restricted during use of natal dens, we excluded locations collected at these dens from all analyses. Using this restricted dataset, we calculated a single 95% and 50% home range (with smoothing factors determined by least squares cross-validation –Seaman & Powell, 1996), and an average distance at which each female was tracked from the refuse pit, for the pre- and postclosure periods.

We compared average distances to the refuse pit before and after closure using a Wilcoxon matched-pairs test. The pooling of locations from multiple individuals to calculate home range and core area size, while necessary for reasons of sample size requirements, prevented statistical comparisons of these two variables before and after pit closure. All distances and fixed kernel home ranges were calculated using Animal Movement Analyst (Hooge & Eichenlaub, 2000) and ArcView GIS 3.2 (Environmental Systems Research Institute, Redlands, CA, U.S.A.).

Because variability in prey abundance over time may influence space use patterns, we monitored prey abundance within the clan territory throughout the study period. As a monthly index of local prey abundance, we counted the total number of wild ungulates within 100 m of 2 4-km road transects twice each month (Fig. 1), and calculated the average number of prey animals counted per sampling event. To investigate differences in prey abundance between pre- and postclosure periods while controlling for the influence of the seasonal ungulate migration, we compared the average prey count for the same 10 months before and after pit closure using a t-test.

To investigate the influence of natural prey abundance on use of the refuse pit, we compared pit utilization during months of high prey abundance, when migratory herds were present in the clan territory, with that during months when only resident herds were present. Migration months were defined as those months when wildebeest were seen within the territory because no resident herds of wildebeest utilize this portion of the Reserve. We focused only on hyenas that were closely monitored in the 16-month preclosure period (≥12 months of tracking), and that were known to use the site with some frequency (>5% of locations within 500 m of the refuse pit). We compared the relative frequency of locations of these hyenas (pooled) within 500 m of the refuse pit during migration months and nonmigration months using a chi-square test.

To investigate the influence of social rank on individual variation in space use relative to the refuse pit, we conducted two separate analyses with females assigned to low or high rank categories relative to the median adult female rank. Individual ranks were assigned based on the outcomes of dyadic agonistic interactions as in Holekamp & Smale (1990). Immigrant males were treated separately as the lowest ranking group. First, to compare qualitatively use of the pit between individuals of different ranks, we calculated the proportion of tracking locations collected within 500 m of the refuse pit for those adult females tracked for ≥12 months while the pit was in use. Second, independent of radiotracking, we documented the composition of hyena groups observed feeding at the refuse pit based on eighteen observation sessions. We compared the proportion of these sessions recording the presence of low-ranking females, high-ranking females and immigrant males. We then compared the number of hyenas present from each rank group at these visits using a Friedman ANOVA, with the number of hyenas from each rank group representing three repeated samples for each observation session. Each rank group contained a total of five individuals in this preclosure period.

All tests were considered statistically significant at α = 0.05 (two-sided), and all analyses were conducted using the STATISTICA software package (Statsoft, 2002). Descriptive statistics are presented as mean ± SE throughout.

Results

  1. Top of page
  2. AbstractRésumé
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Observations of refuse pit use

At least one clan member was present at eighteen visits by researchers to the refuse pit. During these sessions, an average of five hyenas were seen at the site (range: 2–14). The hyenas were often joined at the refuse pit by savanna baboons (Papio cynocephalus), warthogs (Phacochoerus africanus) and various species of vultures. Most edible items were typically consumed, by whichever species were present, within 1–2 h of refuse deposition. Typically only a subset of the hyenas present, if any, were observed to feed at any given time, due to direct and sometimes aggressive competition with warthogs and baboons. At least one subadult hyena was present at 44% of these sessions, the youngest of which was approximately 13 months. None of the subadults were accompanied by their mothers and no hyenas <1 year old were observed at the refuse pit.

Effect of refuse pit on clan space use

We collected a total of 1830 locations from six radiocollared females, with each female monitored for an average of 20 months. Based on locations from the five females monitored both before and after pit closure, home range in the 10 months prior to closure was 10.9 km2 (= 385 locations), and 13.9 km2 (= 385 locations) in the 19 months after closure (Fig. 2). The preclosure core area was 1.6 km2 and included the refuse pit as well as two of the six communal dens utilized during this period (Fig. 2a). After pit closure the core area no longer included the pit, was almost half its previous size (0.9 km2), and contained seven of the eleven communal dens utilized during the postclosure period (Fig. 2b). The distance from hyena tracking locations to the pit was significantly smaller during the preclosure period (inline image = 1.87 ± 0.09 km) than during the postclosure period (inline image = 2.23 ± 0.07 km; = 2.00, < 0.043; Table 1). Differences in space use between the pre- and postclosure periods could not be explained by differences in prey abundance. Average monthly prey counts were similar in the pre- and postclosure periods (pre: inline image = 294, post: inline image = 394; = −0.522, = 0.607).

image

Figure 2.  The 95% home ranges (solid dark lines) and 50% core areas (dotted lines) based on locations from five radiocollared adult female hyenas collected during the 10 months before (a) and 19 months after (b) the closure of the refuse pit. Pit location is indicated as in Fig. 1, and the locations of all communal dens utilized during the respective periods are indicated by solid triangles

Download figure to PowerPoint

Table 1.   Average distances (SE) of adult female hyena tracking locations to the refuse pit for the 10 months prior to the closing of the pit (preclosure) and the 19-months following the closure (postclosure)
HyenaNo. of tracks/periodMean distance (km) to refuse pit
PreclosurePostclosure
NANA1302.19 (0.14)2.51 (0.13)
ATAR1191.89 (0.18)1.98 (0.15)
BACK961.58 (0.18)2.07 (0.13)
WND211.57 (0.38)2.62 (0.22)
CHAC201.39 (0.19)2.25 (0.32)
Pooled locations3851.87 (0.09)2.23 (0.07)

Individual variation in refuse pit utilization

Of six radiocollared females, four (two high-ranking and two low-ranking) were monitored for ≥12 months during operation of the refuse pit. The two high-ranking females were tracked within 500 m of the pit on only two of 179 (1.1%) and four of 202 (2.0%) occasions respectively. In contrast, 29.8% of 178 locations, and 26.2% of 183 locations for the two low-ranking females were within 500 m of the pit. Seventy-five per cent of eighteen refuse pit observation sessions recorded low-ranking adult females present, whereas only 43% and 32% recorded the presence of immigrant males and high-ranking females respectively. At the same eighteen sessions, these three rank groups were not represented equally (Friedman ANOVA χ2 = 15.5, < 0.0005), with low-ranking females being the most numerous individuals at the refuse pit (Fig. 3).

image

Figure 3.  Mean number of high-ranking (HR) females, low-ranking (LR) females and immigrant male hyenas (five individuals per group) that were seen at eighteen refuse pit observation sessions. Sessions included were those at which at least one hyena was observed. Whiskers indicate 95% confidence intervals

Download figure to PowerPoint

Influence of natural prey abundance on refuse pit utilization

Migratory herds were present in the study area for 3 of the 9 months for which both prey and tracking data were available during operation of the refuse site. Unfortunately, only two females in the clan met our criteria for this analysis, yet clear trends were shown by these individuals. These two females were tracked within 500 m of the pit significantly less often during migration months (12.0% of all tracks) than during nonmigration months (38.0% of tracks; χ2 = 19.24, < 0.0001).

Discussion

  1. Top of page
  2. AbstractRésumé
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

In carnivore studies, utilization of human-provided food resources such as those available at garbage dumps often results in reduced individual or group home ranges (e.g. C. latrans –Hidalgo-Mihart et al., 2004; U. arctos –Blanchard & Knight, 1991) or core areas (e.g. Mungos mungo –Gilchrist & Otali, 2002). These observed reductions are presumed to result from a reduction in foraging space requirements due to the addition of a predictable, concentrated food supply. Here, the female group home range was smaller during operation of the refuse pit, yet core area size was smaller following closure of the pit. This discrepancy is probably related to the importance of the communal den in hyena society. Although its influence on space use varies with rank and reproductive condition, space use by all female clan members is highly influenced by the location of the communal den (Boydston et al., 2003). It appears that during its operation, the refuse pit became a focal point of activity for at least some clan members, resulting in an expanded group core area that contained communal den locations and the refuse site. Unlike in garbage-feeding banded mongoose and baboon groups, where core areas were centered on refuse site locations (Altmann & Muruthi, 1988; Gilchrist & Otali, 2002), the location of the communal den probably dictates the location of hyena clan core areas. Furthermore, the location of the den appeared to be independent of the pit location, because den location was similar between the pre- and postclosure periods (Fig. 2).

Use of the refuse pit was most common among low-ranking females, particularly during times of prey scarcity, although there was a notable variation in pit utilization within rank groups. For example, at least one low-ranking uncollared female was seen only once at the refuse pit, and an uncollared high-ranking female was observed at the pit with some regularity. Solely on the basis of rank and its associated priority of access to food, we expected immigrant males to be most dependent on alternate food resources, yet immigrant males were seen less often at the refuse site than low-ranking females. We suspect that competition with baboons and warthogs, combined with competition with the female hyenas that frequented the pit (all of which would out-rank immigrant males) resulted in immigrant males obtaining relatively few benefits from refuse pit visits. Although detailed behavioural records were not collected at the pit to quantify these interactions, both inter- and intraspecific competition at the site were frequently intense. Notably, frequent refuse pit users in our study were not infirm or consistently old, and all were known to be capable of making kills and consuming ungulate carcasses.

The observed shifts in space use, and the propensity of certain clan members to frequent the refuse pit are particularly interesting as they relate to human-carnivore conflict. We suggest that the relatively frequent use of the refuse pit by low-ranking individuals is related to their low priority of access to kills in the clan territory. This skewed utilization of human food sources has been similarly shown in polar bears (Lunn & Stirling, 1985) and black bears (Rogers et al., 1976; Young & Ruff, 1982), where subadults (particularly males among black bears) were the most common age group at garbage dumps. This has been suggested to result from nutritional stress (Lunn & Stirling, 1985), ranging behaviour (Rogers et al., 1976) or necessity of avoiding intraspecific competition (Young & Ruff, 1982), which are all typically elevated in subadult mammalian carnivores, particularly males.

If human refuse attracts hyenas to pastoral villages then, given our results here, we would expect low-ranking hyenas to be more likely to visit these villages and perhaps also to opportunistically attack corralled livestock there. From 2001–2005, eleven known hyenas from two clans defending territories along the Reserve border were found with neck snares, often set at livestock enclosures. Seventy-three per cent of these were either immigrant males or low-ranking natal hyenas. During the same period, six of the seven hyenas from these clans that were either killed during livestock depredation attempts or found dead near villages were also low-ranking. While the possibility exists that low-ranking hyenas are more likely to seek out and attack livestock directly, our space use data suggest that garbage alone can influence movements of hyenas, particularly those of low rank, and that these individuals may therefore be more likely to participate in depredation events.

The potential of the presence of human-provided food sources to influence carnivore space use patterns is well documented. A wolf pack in Italy focused their nightly movements around garbage dumps (Ciucci et al., 1997), and there is a long history in North America of both black bears (Rogers et al., 1976; Herrero, 1983) and grizzly bears (Craighead & Craighead, 1971) visiting garbage dumps with remarkable frequency and predictability. Beckmann & Berger (2003) have related use of these dumps by black bears to an increase in direct conflict with humans, but this problem may be exacerbated when sources of garbage occur in the vicinity of livestock. In an earlier study, we showed that larger pastoral villages along the Reserve border were more likely to suffer livestock losses to hyenas, and suggested that large villages may be more attractive to foraging hyenas due to the larger amounts of refuse produced by them (Kolowski & Holekamp, 2006). We have shown here that even small sources of human refuse have the ability to alter hyena space use patterns and result in disproportionately frequent use of these areas. As refuse and livestock carcasses are common around many pastoral villages surrounding the Reserve, it seems likely that regular nightly movements into village areas by Reserve hyenas (Kolowski & Holekamp, 2006) are associated with utilization of this resource. Because increased hyena use of these village areas is associated with more frequent hyena attacks on livestock (Kolowski & Holekamp, 2006), the ability of human refuse to influence hyena movements makes the presence of these food sources in and around pastoral villages a potentially serious obstruction to efforts to reduce the frequency of livestock depredation events.

Acknowledgements

  1. Top of page
  2. AbstractRésumé
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

We thank the Office of the President of Kenya for allowing us to conduct this research. We also thank the Kenya Wildlife Service, Narok County Council, Mara Intrepids Lodge, and Senior Warden of the Masai Mara National Reserve for their cooperation and assistance. Isla Graham, S. Wahaj and M. Gibbons conducted essential components of the fieldwork with additional help from C. Beaudoin, K. Kapheim, J. Smith and J. Tanner. We are grateful to L. Kierepka and S. Congdon who assisted in the laboratory, and J. Tanner and K. Theis, who provided valuable suggestions on drafts of this manuscript. The research presented here was described in Animal Research Protocol No. 05/05-064-00, approved most recently on 3 April 2006 by the All University Committee on Animal Use and Care at Michigan State University. The work was supported by NSF grants IBN0113170, IBN0343381, and IOB0618022 to K.E.H., and by grants from the Graduate School at Michigan State University to J.M.K. Finally, we thank an anonymous reviewer for helpful comments on this manuscript.

References

  1. Top of page
  2. AbstractRésumé
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  • Altmann, J. & Muruthi, P. (1988) Differences in daily life between semiprovisioned and wild-feeding baboons. Am. J. Primatol. 15, 213221.
  • Beckmann, J.P. & Berger, J. (2003) Using black bears to test ideal-free distribution models experimentally. J. Mammal. 84, 594606.
  • Blanchard, B.M. & Knight, R.R. (1991) Movements of Yellowstone Grizzly Bears. Biol. Conserv. 58, 4167.
  • Boydston, E.E., Kapheim, K.M., Szykman, M. & Holekamp, K.E. (2003) Individual variation in space utilization by female spotted hyenas. J. Mammal. 84, 10061018.
  • Broten, M.D. & Said, M.Y. (1995) Population trends of ungulates in and around Kenya’s Masai Mara Reserve. In: Serengeti II: Dynamics, Management, and Conservation of an Ecosystem (Eds A. R. E.Sinclair and P.Arcese). University of Chicago Press, Chicago, IL.
  • Ciucci, P., Boitani, L., Francisci, F. & Andreoli, G. (1997) Home range, activity and movements of a wolf pack in central Italy. J. Zool. 243, 803819.
  • Cooper, S.M., Holekamp, K.E. & Smale, L. (1999) A seasonal feast: long-term analysis of feeding behaviour in the spotted hyaena Crocuta crocuta. Afr. J. Ecol. 37, 149160.
  • Craighead, J.J. & Craighead, F.C. (1971) Grizzly bear-man relationships in Yellowstone National Park. BioScience 21, 845857.
  • Doncaster, C.P., Dickman, C.R. & Macdonald, D.W. (1990) Feeding ecology of red foxes (Vulpes vulpes) in the city of Oxford, England. J. Mammal. 71, 188194.
  • Durant, S.M. (1998) Competition refuges and coexistence: an example from Serengeti carnivores. J. Anim. Ecol. 67, 370386.
  • East, M.L. & Hofer, H. (2001) Male spotted hyenas (Crocuta crocuta) queue for status in social groups dominated by females. Behav. Ecol. 12, 558568.
  • Ewer, R.F. (1973) The Carnivores. Cornell University Press, Ithaca.
  • Fedriani, J.M., Fuller, T.K. & Sauvajot, R.M. (2001) Does availability of anthropogenic food enhance densities of omnivorous mammals? An example with coyotes in southern California. Ecography 24, 325331.
  • Frank, L.G. (1986) Social organization of the spotted hyaena (Crocuta crocuta) II. Dominance and reproduction. Anim. Behav. 34, 15101527.
  • Fuller, T.K. & Keith, L.B. (1980) Wolf population dynamics and prey relationships in northeastern Alberta. J. Wildl. Manage. 44, 583602.
  • Gasaway, W.C., Mossestad, K.T. & Stander, P.E. (1991) Food acquisition by spotted hyaenas in Etosha National Park, Namibia: predation versus scavenging. Afr. J. Ecol. 29, 6475.
  • Gilchrist, J.S. & Otali, E. (2002) The effects of refuse-feeding on home-range use, group size, and intergroup encounters in the banded mongoose. Can. J. Zool. 80, 17951802.
  • Henschel, J.R. & Skinner, J.D. (1987) Social relationships and dispersal patterns in a clan of spotted hyaenas Crocuta crocuta in the Kruger National Park. S. Afr. J. Zool. 22, 1824.
  • Henschel, J.R. & Skinner, J.D. (1990) The diet of the spotted hyenas Crocuta crocuta in Kruger National Park. Afr. J. Ecol. 28, 6982.
  • Herrero, S. (1983) Social behavior of black bears at a garbage dump in Jasper National Park. Int. Conf. Bear Res. Manage. 5, 5470.
  • Hidalgo-Mihart, M.G., Cantu-Salazar, L., Lopez-Gonzalez, C.A., Fernandez, E.C. & Gonzales-Romero, A. (2004) Effect of a landfill on the home-range and group size of coyotes (Canis latrans) in a tropical deciduous forest. J. Zool. 263, 5563.
  • Hofer, H. & East, M.L. (1993) The commuting system of Serengeti spotted hyaenas: how a predator copes with migratory prey II. Intrusion pressure and commuter’s space use. Anim. Behav. 46, 559574.
  • Holekamp, K.E. & Smale, L. (1990) Provisioning and food sharing by lactating spotted hyenas, Crocuta crocuta (Mammalia: Hyaenidae). Ethology 86, 191202.
  • Holekamp, K.E., Smale, L. & Szykman, M. (1996) Rank and reproduction in the female spotted hyaena. J. Reprod. Fertil. 108, 229237.
  • Holekamp, K.E., Cooper, S.M., Katona, C.I., Berry, N.A., Frank, L.G. & Smale, L. (1997) Patterns of association among female spotted hyenas (Crocuta crocuta). J. Mammal. 78, 5574.
  • Hooge, P.N. & Eichenlaub, B. (2000) Animal Movement Extension to Arcview. ver. 2.0. U.S. Geological Survey, Anchorage, AK.
  • Knight, R.R. & Eberhardt, L.L. (1985) Population dynamics of Yellowstone grizzly bears. Ecology 66, 323334.
  • Knight, R.R., Blanchard, B.M. & Eberhardt, L.L. (1988) Mortality patterns and population sinks for Yellowstone grizzly bears, 1973–1985. Wildl Soc Bull 16, 121125.
  • Kolowski, J.M. & Holekamp, K.E. (2006) Spatial, temporal, and physical characteristics of livestock depredations by large carnivores along a Kenyan reserve border. Biol. Conserv. 128, 529541.
  • Kolowski, J.M. & Holekamp, K.E. (2007) Daily patterns of activity in the spotted hyena. J. Mammal. 88, 10171028.
  • Kruuk, H. (1972) The Spotted Hyena: a Study of Predation and Social Behavior. University of Chicago Press, Chicago, IL.
  • Kruuk, H. (1981) The Effects of Large Carnivores on Livestock and Animal Husbandry in Marsabit District, Kenya. UNEP-MAB integrated project in arid lands. IPAL technical report E-4.
  • Linnell, J.D.C., Odden, J., Smith, M.E., Aanes, R. & Swenson, J.E. (1999) Large carnivores that kill livestock: do “problem individuals” really exist? Wildl. Soc. Bull. 27, 698705.
  • Lucherini, M. & Crema, G. (1994) Seasonal variation in diet and trophic niche of the red fox in an alpine habitat. Z. Säugetierkunde 59, 18.
  • Lunn, N.J. & Stirling, I. (1985) The significance of supplemental food to polar bears during the ice-free period of Hudson Bay. Can. J. Zool. 63, 22912297.
  • Mills, M.G.L. & Hofer, H. (1998) Hyaenas: Status Survey and Conservation Action Plan. IUCN/SSC Hyaena Specialist Group, IUCN.
  • Mills, S.L. & Knowlton, F.F. (1991) Coyote space use in relation to prey abundance. Can. J. Zool. 69, 15161521.
  • Norton-Griffiths, M. (1995) Economic incentives to develop the rangelands of the Serengeti: implications for wildlife conservation. In: Serengeti II: Dynamics, Management, and Conservation of an Ecosystem (Eds A. R. E.Sinclair and P.Arcese). University of Chicago Press, Chicago, IL.
  • Ogada, M.O., Woodroffe, R., Oguge, N.O. & Frank, L. (2003) Limiting depredation by African carnivores: the role of livestock husbandry. Conserv. Biol. 17, 15211530.
  • Ottichilo, W.K., De Leeuw, J., Skidmore, A.K., Prins, H.H.T. & Said, M.Y. (2000) Population trends of large non-migratory wild herbivores and livestock in the Masai Mara ecosystem, Kenya, between 1977 and 1997. Afr. J. Ecol. 38, 202216.
  • Rogers, L.L., Kuehn, D.W., Erickson, A.W., Harger, E.M., Verme, L.J. & Ozoga, J.J. (1976) Characteristics and management of black bears that feed in garbage dumps, campgrounds, or residential areas. International Conference on Bear Research and Management 3, 169175.
  • Salvador, A. & Abad, P.L. (1987) Food habits of a wolf population (Canis lupus) in Leon province, Spain. Mammalia 51, 4552.
  • Seaman, D.E. & Powell, R.A. (1996) An evaluation of the accuracy of kernel density estimators for home range analysis. Ecology 77, 20752085.
  • Serneels, S. & Lambin, E.F. (2001) Impact of land-use changes on the wildebeest migration in the northern part of the Serengeti-Mara ecosystem. J. Biogeogr. 28, 391407.
  • Smale, L., Frank, L.G. & Holekamp, K.E. (1993) Ontogeny of dominance in free-living spotted hyaenas: juvenile rank relations with adult females and immigrant males. Anim. Behav. 46, 467477.
  • Smale, L., Nunes, S. & Holekamp, K.E. (1997) Sexually dimorphic dispersal in mammals: patterns, causes, and consequences. Adv. Study Behav. 26, 181250.
  • Spong, G. (2002) Space use in lions, Panthera leo, in the Selous Game Reserve: social and ecological factors. Behav. Ecol. Sociobiol. 52, 303307.
  • Statsoft. (2002) STATISTICA 6.1 (data analysis software system). StatSoft, Tulsa, OK.
  • Tilson, R.T. & Hamilton, W.J.I. (1984) Social dominance and feeding patterns of spotted hyaenas. Anim. Behav. 32, 715724.
  • Walpole, M.J., Karanja, G.G., Sitati, N.W. & Leader-Williams, N. (2003) Wildlife and People: Conflict and Conservation in Masai Mara, Kenya. Wildlife and Development Series No. 14, International Institute for Environment and Development.
  • Yom-Tov, Y., Ashkenazi, S. & Viner, O. (1995) Cattle predation by the golden jackal Canis aureus in the Golan Heights, Israel. Biol. Conserv. 73, 1922.
  • Young, B.F. & Ruff, R.L. (1982) Population dynamics and movements of black bears in east central Alberta. J. Wildl. Manage. 46, 845860.