Increased Home Range Size Research Articles

The behavior of Broad-tailed hummingbirds is altered by cycles of human activity in a forested area converted into agricultural land.

By changing the circumstances in which animals make their behavioral decisions, weekly cycles of human activity might cause changes in wildlife behavior. For example, when there is more human activity in a location, animals may become more vigilant, which can decrease the time they spend foraging, or roam farther from home, leading to increased home range size. Overall, there has been little exploration of how animal species living in locations that have undergone land use change are affected by the temporal dynamics of human activity levels. In this study, we aimed to analyze the effect of the weekend on agricultural activities and hummingbird territorial activity. We examined differences between weekdays and weekends in factors previously shown to follow weekly cyclical patterns, such as pedestrian presence, traffic, and the presence of domestic animals. We hypothesized that territorial hummingbirds would respond to these weekly cycles of human activity by altering their behavior. We studied Broad-tailed hummingbird territories in forested areas that had been transformed to agriculture lands in central Mexico. We evaluated whether territorial individuals changed their behaviors (i.e., chases of intruders, foraging within their territory, number of intruders allowed to forage in the territory) in response to variation between weekdays and weekends in the number of pedestrians, cyclists, dogs, farm animals and vehicles. We found that the level of agriculture-related human activities showed a weekly cycle at our study site. On weekdays there was higher traffic of pedestrians, cyclists, dogs, farm animals and vehicles, compared to the weekends. Hummingbirds responded to these weekday-weekends differences by changing their territorial behavior. Compared to weekends, on weekdays hummingbirds showed a decrease in defense (number of chases) as well as the use of their territory (number of flowers visited), which allowed increased access to intruders (number of visited flowers by intruders). Our findings suggest that variation in agriculture-related human activities between weekdays and weekends can alter the territorial behavior of hummingbirds. Behavioral shifts seem to be related to these human activity cycles, leading hummingbirds to reduce chases and feeding during weekdays when human activity is highest, but increasing both behaviors during times of minimal disturbance.

Sexual, allometric and forest cover effects on giant anteaters' movement ecology.

Knowing the influence of intrinsic and environmental traits on animals’ movement is a central interest of ecology and can aid to enhance management decisions. The giant anteater (Myrmecophaga tridactyla) is a vulnerable mammal that presents low capacity for physiological thermoregulation and uses forests as thermal shelters. Here, we aim to provide reliable estimates of giant anteaters’ movement patterns and home range size, as well as untangle the role of intrinsic and environmental drivers on their movement. We GPS-tracked 19 giant anteaters in Brazilian savannah. We used a continuous-time movement model to estimate their movement patterns (described by home range crossing time, daily distance moved and directionality), and provide an autocorrelated kernel density estimate of home range size. Then, we used mixed structural equations to integratively model the effects of sex, body mass and proportion of forest cover on movement patterns and home range size, considering the complex net of interactions between these variables. Male giant anteaters presented more intensive space use and larger home range than females with similar body mass, as it is expected in polygynous social mating systems. Males and females increased home range size with increasing body mass, but the allometric scaling of intensity of space use was negative for males and positive for females, indicating different strategies in search for resources. With decreasing proportion of forest cover inside their home ranges, and, consequently, decreasing thermal quality of their habitat, giant anteaters increased home range size, possibly to maximize the chances of accessing thermal shelters. As frequency and intensity of extreme weather events and deforestation are increasing, effective management efforts need to consider the role of forests as an important thermal resource driving spatial requirements of this species. We highlight that both intrinsic and environmental drivers of animal movement should be integrated to better guide management strategies.

Potential of a no-take marine reserve to protect home ranges of anadromous brown trout (Salmo trutta).

The extent to which no‐take marine reserves can benefit anadromous species requires examination. Here, we used acoustic telemetry to investigate the spatial behavior of anadromous brown trout (sea trout, Salmo trutta) in relation to a small marine reserve (~1.5 km2) located inside a fjord on the Norwegian Skagerrak coast. On average, sea trout spent 42.3 % (±5.0% SE) of their time in the fjord within the reserve, a proportion similar to the area of the reserve relative to that of the fjord. On average, sea trout tagged inside the reserve received the most protection, although the level of protection decreased marginally with increasing home range size. Furthermore, individuals tagged outside the reserve received more protection with increasing home range size, potentially opposing selection toward smaller home range sizes inflicted on fish residing within reserves, or through selective fishing methods like angling. Monthly sea trout home ranges in the marine environment were on average smaller than the reserve, with a mean of 0.430 (±0.0265 SE) km2. Hence, the reserve is large enough to protect the full home range of some individuals residing in the reserve. Synthesis and applications: In general, the reserve protects sea trout to a varying degree depending on their individual behavior. These findings highlight evolutionary implications of spatial protection and can guide managers in the design of marine reserves and networks that preserve variation in target species' home range size and movement behavior.

Stocked rainbow trout (Oncorhynchus mykiss) affect space use by Warpaint Shiners (Luxilus coccogenis)

AbstractDue to widespread stocking, Rainbow Trout (Oncorhynchus mykiss Walbaum) are perhaps the most widely distributed invasive species in the world. Nonetheless, little is known about the effects of stocked Rainbow Trout on native non‐game species. We conducted experiments in an artificial stream to assess the effects of hatchery Rainbow Trout on home range and behaviour of Warpaint Shiners (Luxilus coccogenis Cope), a common minnow frequently found in stocked Southern Appalachian streams. We used the LoCoH algorithm to generate polygons describing the home ranges used by Warpaint Shiners. When a stocked trout was present Warpaint Shiners: (a) increased home range size by 57%, (b) were displaced into higher velocity mesohabitats, and (c) reduced mean overlap between the home ranges of individual warpaint shiners. Rainbow Trout did not significantly affect the edge/area ratio of Warpaint Shiner home ranges. Warpaint Shiner density (two and five fish treatments) did not significantly affect any response variable. Displacement from preferred microhabitats and increases in home range size likely result in increased energy expenditure and exposure to potential predators (i.e., decreased individual fitness) of Warpaint Shiners when stocked trout are present.

Pine marten density in lowland riparian woods: A test of the Random Encounter Model based on genetic data

In marginal habitats, populations should reach lower densities, as a consequence of both lower overall abundance and increasing home range size. To test if recently colonized riparian woods crossing intensively cultivated lowlands of NW Italy represent marginal habitats for the forest-specialist pine marten Martes martes, we assessed its population density by a recently developed, camera-trap-based non-invasive method, the Random Encounter Model (REM). As the central assumption of the REM is that animals move randomly with respect to cameras, we suspected that this method may be unsuitable for species with a strong tendency to use linear elements of the territory as usual paths and select habitats, such as woodland, which are likely to be under-represented in fragmented landscapes. To test for the efficacy of the REM, we also applied a faecal DNA-based genetic census to obtain an independent estimate of the minimum number of individuals occurring in the study area. Camera-trapping used 10 camera-traps, deployed for 10days within a 2km2 large unit, for a total of 6 units and 12km2. Pine marten density was estimated at 0.48 (0.36–0.60) ind/km2. All the faecal samples identified by a mDNA-based PCR-RFLP method as pine marten were genotyped at 15 microsatellite loci using a multiplex protocol. We identified 15 different individuals, corresponding to a density ranging between 0.8 and 2.0ind/km2. Using the most conservative genetic estimate, the REM underestimated population density of about 60% proving to be unreliable for estimating pine marten population size. We suggest that this may be the case for elusive species for which the assessment of average daily movements cannot be achieved without the use of invasive methods.

Males matter: Increased home range size is associated with the number of resident males after controlling for ecological factors in wild Assamese macaques.

There is increasing evidence of male resource defense during intergroup encounters in non-human primates. Only few studies showed a reproductive benefit of having more males in a group, and evidence only comes from territorial species, or from species with relatively small male group sizes where males are less prone to suffer from collective action problems. We investigated the effect of male group size on home range size and female reproductive success in a non-territorial species with male dispersal and large male group sizes. We studied one wild group of Assamese macaques (Macaca assamensis) by following them almost daily (June 2006-September 2012) and collected spatial, behavioral, climate and spatiotemporal data on food plants. Among ecological factors, decreasing rainfall and a statistical interaction between food abundance and distribution were positively related to home range size. After controlling for ecological predictors, we found that male group size but not overall group size had a significant positive effect on full and core home range size. A simple correlation analysis suggests that such an increase in home range area, presumably increasing access to food resources, can be associated with increased female fecundity measured as the proportion or the number of females conceiving in a given year. Within the limitations of this study, the results suggest that male resource defense could be a strategy benefitting both sexes if male reproductive skew was low and many males benefited from increased female fertility.

Linking lab activity with growth and movement in the wild: explaining pace-of-life in a trout stream

Theory suggests that consistent individual differences in activity are linked to life history where high activity is associated with rapid growth, high dispersal tendency, and low survival (the pace-of-life syndrome hypothesis). We addressed this influential hypothesis by combining behavioral studies with fine-scale positional scoring in nature, estimating how individual movement strategies in brown trout ( Salmo trutta ) associate with fitness correlates (growth and survival) in the wild. Initial dispersal in the wild was positively related to the laboratory activity. Moreover, the growth of individuals with high laboratory activity decreased with increasing home range size, whereas the growth of individuals with lower laboratory activity increased slightly with increasing home range size. Survival in the wild was not associated with laboratory activity. Our results do not support the original pace-of-life syndrome hypothesis. As an alternative explanation, we suggest that the growth of individuals adopting a high-activity strategy is more sensitive to variation in resource abundance (indicated by home range size) than the fitness individuals adopting a more passive strategy.

Quantifying spatial–temporal patterns in wildlife ranges using STAMP: A grizzly bear example

Geographical spatial analysis approaches are ideally applied to studies of wildlife habitat use when spatial data, such as telemetry data or spatial ranges, are available. For instance, it is often desirable to quantify spatial–temporal patterns of home ranges, which are typically delineated as polygons and represent areas of habitat that support wildlife functions. Changes to home ranges over time are often presented as variation in mean polygon area. This two-dimensional approach ignores potentially important spatial–temporal characteristics of habitat use, including site fidelity, range contraction, and expansion. Using Spatial–Temporal Analysis of Moving Polygons (STAMP) we examined a set of movement data for a subpopulation of adult female grizzly bears (Ursus arctos) for the period from 1999 to 2003 in the Rocky Mountain foothills region of Alberta, Canada. Home range change was quantified over two-year periods and evaluated on the basis of variable offspring dependency (i.e., whether the females had no cubs, cubs-of-the-year (COY), or yearling cubs) and foraging season. Solitary bears showed the greatest amount of home range fidelity, with an increase in range size during the mating season. Female grizzly bears with offspring experienced substantial home range change. Sows with COY had a reduced maternal home range size, especially during mating season, while those with yearling offspring had an increased home range size. The patterns of home range change were consistent with those expected if some combination of mobility and infanticide were the driving ecological mechanisms. We conclude that offspring dependency does not impact the degree of site fidelity but does impact the nature of home range change experienced. We also suggest that the spatial–temporal change in female grizzly home ranges could be used to infer breeding status and as a population monitoring tool. A geographical approach to home range change provides a simple and quantitative approach to mapping spatial–temporal patterns of habitat use and animal movement.

Sexual and seasonal differences of space use in Alpine chamois

In spite of its wide distribution, little information has been published on factors affecting space use of northern chamois Rupicapra rupicapra. We radio-tracked 12 (≥ 4 years old) adult male and nine adult female chamois, for 2 years (from April to December), in an area of the south-western Italian Alps. Eight males occupied stable and small home ranges (“resident” males), while four moved between seasonal areas (“migrant” males). Residents showed smaller, stable home ranges, at lower altitudes than those of adult females, and selected forest, scrub, bush and meadow, avoiding rocks and scree. Females increased home range size in July-August, when they moved to rocky areas at the higher altitudes, and decreased it in November-December, at rut time. In spring and autumn, females selected both meadows and larch forest/scrub. Sexual and seasonal differences in space use, which reflected a marked sexual segregation, may have been linked to energetic and mating requirements, with females selecting high-quality feeding areas because of their energy demands during gestation and lactation. From spring to autumn, males remained at lower altitudes, in lower-quality habitats, only visited by females in the mating season.

Neighboring groups and habitat edges modulate range use in Phayre’s leaf monkeys (Trachypithecus phayrei crepusculus)

An animal’s use of space may be strongly influenced by habitat edges and neighboring conspecifics encountered in and around its home range. Habitat edges are known to affect species density and distribution, but their impact on home range use is largely unknown. Additionally, among large animals, interactions with neighbors become particularly important as increasing home range size leads to decreasing exclusivity of resource use, but the effect of neighbors on home range use remains poorly understood. Here, we examine the influence of neighbors and habitat edges on the ranging patterns of three groups of Phayre’s leaf monkeys (Trachypithecus phayrei crepusculus) in northeast Thailand over a period of more than 2 years. The study animals occupied dry evergreen forest, and adjacent patches of dry dipterocarp forest created a habitat edge and formed barriers between some groups. We found that the use of home range interiors was 50–90% higher than the border areas, indicating concentrated use of resources within the home range. The use of peripheral areas was influenced by social organization, the presence of neighboring groups, and forest edges. While one multimale group showed no particular habitat preference, two single-male groups preferred areas bordering dry dipterocarp habitat and avoided areas bordering neighboring groups, suggesting that the threat of neighbors mediated border presence. Additionally, groups may have been attracted to the forest edge, where conspecific competitors are absent and increased sunlight may increase resource abundance and/or quality. This study revealed that the use of border areas can be modulated by neighboring groups and habitat edges, thereby adding to our understanding of home range use among territorial species in heterogeneous habitats.

Abrupt spatial and numerical responses of overabundant foxes to a reduction in anthropogenic resources

Summary 1. Carnivore overabundance that results from exploitation of human derived resources can have numerous detrimental effects on local human populations and ecological communities. Experimental studies on the responses of overabundant carnivores to reductions of such resources are necessary to understand the effectiveness and impacts of resource reduction. 2. We conducted controlled experiments in two villages in which we drastically reduced the availability of anthropogenic food sources in half of each village. Spatial and numerical responses of radio‐collared red foxes Vulpes vulpes were recorded and contrasted with those of radio‐collared foxes in three similar untreated villages and pristine areas in the region. In total, we looked at survival rates of 134 foxes. 3. Prior to the resource manipulation, home range sizes (0·47 and 0·56 km2) and population densities (30 and 36 foxes km−2) in the two villages were comparable to documented low and high‐end values, respectively. 4. Fast and distinct spatial responses were observed in response to the resource manipulation, and were manifested in either increased home range size or home range shifts. In one village, foxes exposed to reduced resource availability more than doubled their home range size. 5. Survival rates of individuals in the treated areas were drastically reduced. Actual fox mortality in the two treated areas reached 100% and 64% within 12 months of the onset of resource manipulation. Estimated monthly survival in the two treated areas declined from 0·96–0·98 and 0·98–0·99 (∼0·69 and 0·78 derived annual survival) before treatment to 0·80–0·83 and 0·92–0·94 (∼<0·01 and 0·42 derived annual survival) after treatment, respectively. By contrast, average monthly survivorship in pristine areas was nearly 0·97 (∼0·69 annual survival) and in the untreated areas and other non‐treated villages was 0·95–0·99 (∼0·54–0·89 annual survival). 6. Synthesis and applications. This study demonstrates that sound waste disposal measures are very effective in controlling populations of overabundant carnivores. Contrary to common notion, the response of foxes to reduced resources was fast, manifested more by reduced survival than by successful dispersal into adjacent pristine areas. The results offer support to the Resource Dispersion Hypothesis regarding both home range size and density (suggested by the sharp decrease in survival) as a function of the spatial and temporal dispersion of resource.

Marine reserve networks for species that move within a home range

Marine reserves are expected to benefit a wide range of species, but most models used to evaluate their effects assume that adults are sedentary, thereby potentially overestimating population persistence. Many nearshore marine organisms move within a home range as adults, and there is a need to understand the effects of this type of movement on reserve performance. We incorporated movement within a home range into a spatially explicit marine reserve model in order to assess the combined effects of adult and larval movement on persistence and yield in a general, strategic framework. We describe how the capacity of a population to persist decreased with increasing home range size in a manner that depended on whether the sedentary case was maintained by self persistence or network persistence. Self persistence declined gradually with increasing home range and larval dispersal distance, while network persistence decreased sharply to 0 above a threshold home range and was less dependent on larval dispersal distance. The maximum home range size protected by a reserve network increased with the fraction of coastline in reserves and decreasing exploitation rates outside reserves. Spillover due to movement within a home range contributed to yield moderately under certain conditions, although yield contributions were generally not as large as those from spillover due to larval dispersal. Our results indicate that, for species exhibiting home range behavior, persistence in a network of marine reserves may be more predictable than previously anticipated from models based solely on larval dispersal, in part due to better knowledge of home range sizes. Including movement within a home range can change persistence results significantly from those assuming that adults are sedentary; hence it is an important consideration in reserve design.

Female home range size and the evolution of social organization in macropod marsupials

Summary1. Traditional explanations for interspecific variation in home range size are based almost exclusively on analysis of northern hemisphere eutherian mammals. These suggest that variation in body size is the most important factor, while climate and diet are less important. The generality of these explanations is tested using a novel database on macropod marsupials (kangaroos and allies).2. We found a 490‐fold difference in home range size and a 50‐fold difference in body weight amongst macropods. In agreement with studies on eutherians, female home range size was strongly correlated with body weight.3. However, unlike the pattern in eutherians, climate was more strongly associated with home range size than was body weight: annual rainfall explained more than half of the variation, while group size (6%) and population density (8%) were minor explanatory variables, and female body weight explained no further variation.4. When we used a phylogeny‐based comparative method, annual rainfall explained 32% of the variation and body size a further 16%.5. Sex differences in home range size were not explained by body size dimorphism, but were strongly related to rainfall and less strongly related to the degree of female home range overlap. Species with large sex differences in home range size lived in high‐rainfall habitats where female ranges were small.6. We suggest that climate has been a key factor in social evolution of macropods. In species inhabiting productive habitats, small female home ranges allow males to overlap with more females by increasing home range size. Males often compete for females by searching widely. In less productive habitats, males cannot further increase or defend their already large home ranges, resulting in similar‐sized ranges in both sexes. Where female home range overlap is high, males need not increase home ranges as much, but this effect is secondary to that of climate.7. In agreement with the theory that competitive searching by males is not necessarily related to body size, species with extreme size dimorphism had no sex difference in home range size, and species with extreme home range differences between the sexes showed no particular pattern of dimorphism.8. Variation among macropod species in home range size and social organization is more closely correlated with variation in habitat productivity, and is less related to body size, diet, density and group size, than predicted by eutherian‐based explanations.

Determinants of Home Range Size for Polar Bears (Ursus maritimus).

The mean home range size of female polar bears (Ursus maritimus; 125 100 km2 ± 11 800; n = 93) is substantially larger than the predicted value (514 km2 ) for a terrestrial carnivore of similar weight. To understand this difference, we correlated home range size and sea ice characteristics. Home range size was related to (i) the ratio of land vs. sea within a given home range (42% of explained variance), and (ii) seasonal variation in ice cover (24%). Thus, bears using land during the ice-free season had larger home ranges and bears living in areas of great seasonal variation in ice cover also had larger home ranges. In another analysis we investigated how variation in a bear's environment in space and time affects its choice of home range. We found that polar bears adjusted the size of their home range according to the amount of annual and seasonal variation within the centre of their home range. For example, polar bears experiencing unpredictable seasonal and annual ice tended to increase their home range size if increasing home range size resulted in reducing variation in seasonal and annual ice. Polar bears make trade-offs between alternate space-use strategies. Large home ranges occur when variable ice cover is associated with more seals but also a more unpredictable distribution of those seals.

Experimental manipulation of breeding density and litter size: effects on reproductive success in the bank vole

1. Reproductive success of individual females may be determined by density‐dependent effects, especially in species where territory provides the resources for a reproducing female and territory size is inversely density‐dependent. 2. We manipulated simultaneously the reproductive effort (litter size manipulation: ± 0 and + 2 pups) and breeding density (low and high) of nursing female bank voles Clethrionomys glareolus in outdoor enclosures. We studied whether the reproductive success (number and quality of offspring) of individual females is density‐dependent, and whether females can compensate for increased reproductive effort when not limited by saturated breeding density. 3. The females nursing their young in the low density weaned significantly more offspring than females in the high density, independent of litter manipulation. 4. Litter enlargements did not increase the number of weanlings per female, but offspring from enlarged litters had lower weight than control litters. 5. In the reduced density females increased the size of their home range, but litter manipulation had no significant effect on spacing behaviour of females. Increased home range size did not result in heavier weanlings. 6. Mother's failure to successfully wean any offspring was more common in the high density treatment, whereas litter manipulation or mother's weight did not affect weaning success. 7. We conclude that reproductive success of bank vole females is negatively density‐dependent in terms of number, but not in the quality of weanlings. 8. The nursing effort of females (i.e. the ability to provide enough food for pups) seems not to be limited by density‐dependent factors.

Spacing behaviour and habitat use of axis deer (Axis axis) in lowland Nepal

A total of 17 axis deer (Axis axis) (12 females, 5 males) were radio-instrumented in Bardia National Park in lowland Nepal, and 1921 locations of females and 605 locations of males were obtained during the 2-year study period. Both the annual home ranges (135 ± 33 and 204 ± 38 (SD) ha for females and males, respectively) and the seasonal home ranges were quite small compared with those reported in another study in Nepal. We present evidence that this difference is due to a more fine-grained habitat mosaic in Bardia. Males used larger areas than females in the monsoon and the hot part of the dry season. The deer were sedentary, with a mean seasonal home range overlap between 49 and 86%, and seasonal occupancy centres were all located less than 1300 m apart. Mean seasonal home range size (68 and 110 ha for females and males, respectively) was smallest in the cool part of the dry season. The rutting period did not seem to have any major effect on the ranging behaviour, as neither males nor females increased home range size from the pre-rut to the rutting period. The deer used riverine forest preferentially during the cool-dry and hot-dry seasons, whereas sal forest was the preferred habitat during the monsoon and the cool-dry season. Grasslands were preferentially utilized by females at night during the hot-dry season, presumably because of improved forage quality following cutting and burning. Males were more associated with riverine and sal forest than were females, while females used grassland areas more than males did.

Demography and Conservation of an Endangered Primate, Brachyteles arachnoids

Abstract: Demographic data were obtained on one group of muriquis (Brachyteles arachnoides) over an 8‐year period at Fazenda Montes Claros, Minas Gerais, Brazil. During this period, the group rapidly increased in size, growing from 22 to 43 individuals due to 21 births. Eight disappearances or emigrations were offset by eight immigrations. The group also maintained a stable age‐sex class distribution. Inter‐birth intervals averaged 33.8 months, and age at first reproduction was 71/2% years, or 2.7 interbirth intervals. The high birth rate and low mortality rate, along with increased group fissioning and increased home range size, indicate that this group of muriquis is in a stage of expansion. These demographic data also suggest that some small populations of endangered primates can expand in well‐protected babitats without apparent signs of overcrowding or deleterious effects of close inbreeding. These data, as well as the documentation of female migration and male philopatry, provide important guidelines for future management plans for this species.

Social tolerance and proximate mechanisms of dispersal among winter groups of meadow voles, Microtus pennsylvanicus

Proximate mechanisms for movement among communal groups of meadow voles were examined during two winter seasons. Radiotelemetry and live trapping were used to identify group members and monitor the movement of voles. Paired encounters between individuals removed from the field indicated that aggression neither precipitated nor prevented movement of animals between groups during winter. Dispersal most often occurred in conjuction with loss of nestmates to predation. The removal of nestmates resulted in increased home range size and movement between groups for males, but not for females. With the onset of reproduction, aggression increased toward individuals from other groups, but not toward nestmates. Winter groups did not break up with the onset of breeding, but these groups were closed to the immigration of new members.

Bobcat Habitat Use and Home Range Size in Relation to Prey Density

Bobcat (Felis rufus) diet, habitat use, and home range size were studied in relation to snowshoe hare (Lepus americanus) density and distribution in 2 areas in Maine during 1979-84. Hare remains occurred in 63-76% of bobcat feces collected during all seasons in both areas. Habitat use patterns of 12 transmitter-equipped bobcats in eastern Maine indicated that they used hardwood understories more, and softwood and mixedwood understories less than expected (P 5* (P < 0.05). The average home range of resident male bobcats (95.7 kmn2) was 3 x as large as that of resident females (31.2 km2) (P < 0.05), and home range size was correlated with bobcat weight (r2 = 0.45, P < 0.002). Metabolic home range size (km2/kg075 body wt) of bobcats was inversely correlated with stem cover unit density and estimated hare density (r2 = 0.22, P < 0.05). Estimated hare density and average topographic slope within bobcat home ranges accounted for 50% of the variation in metabolic home range size (P < 0.006). J. WILDL. MANAGE. 50(1):110-117 Many factors influence vertebrate habitat use and home range size, including energy requirements, prey distribution and density, reproductive requirements, and intraand interspecific relations (Stenger 1958, McNab 1963, Schoener 1968, Smith 1968). Among these, prey density has been reported to be inversely correlated with home range size (Smith 1968, Holmes 1970, Mares et al. 1976). Large variation has been observed in bobcat home range sizes. Bailey (1974) reported bobcats in Idaho occupied ranges from 9 to 108 km , and bobcats in Alabama occupied ranges <4 km2 (Miller 1980). Buie (1980) observed a 4-fold increase in home range size in South Carolina 13 years after Marshall and Jenkins (1967) studied bobcats in the same area. Buie suggested that changes in land-use patterns caused declines in prey populations and resulted in decreased bobcat density and increased home range size. Snowshoe hares are the major prey of bobcats in Maine (May 1981, Major 1983). Therefore, bobcat habitat use within home ranges should be influenced by the distribution of hares. Bobcats occurring in areas with relatively dense hare populations may occupy smaller ranges than bobcat in areas with low hare densities. The objective of our study was to determine the relati nship between bobcat habitat use and home range s ze and snowshoe hare distribution and abundance in Maine. This research was supported by the Maine Coop. Wildl. Res. Unit, U.S. Fish and Wildl. Serv., Maine Dep. Inland Fish. and Wildl., Wildl. Manage. Inst., and the Univ. Maine, cooperating. A. G. Clark, J. H. Hunt, and L. Perry made valuable contributions in executing and funding this study. We thank students at the Coll. For. Resour., Univ. Maine, and Unity Coll. that provided field assistance. We also thank J. W. Ault III; J. R. Gilbert; G. L. Jacobson, Jr.; D. M. Leslie, Jr.; R. B. Owen, Jr.; and R. E. Rolley for reviewing this report. This is contribution 1078 from Maine Agric. Exp. Stn.