Variation In Home Range Size Research Articles

Locomotion in some small to medium-sized mammals: a geometric morphometric analysis of the penultimate lumbar vertebra, pelvis and hindlimbs

We assessed the influence of a variety of aspects of locomotion and ecology including gait and locomotor types, maximal running speed, home range, and body size on postcranial shape variation in small to medium-sized mammals, employing geometric morphometric analysis and phylogenetic comparative methods. The four views analyzed, i.e., dorsal view of the penultimate lumbar vertebra, lateral view of the pelvis, posterior view of the proximal femur and proximal view of the tibia, showed clear phylogenetic signal and interesting patterns of association with movement. Variation in home range size was related to some tibia shape changes, while speed was associated with lumbar vertebra, pelvis and tibia shape changes. Femur shape was not related to any locomotor variables. In both locomotor type and high-speed gait analyses, locomotor groups were distinguished in both pelvis and tibia shape analyses. These results suggest that adaptations to both typical and high-speed gaits could explain a considerable portion of the shape of those elements. In addition, lumbar vertebra and tibia showed non-significant relationships with body mass, which suggests that they might be used in morpho-functional analyses and locomotor inferences on fossil taxa, with little or no bias for body size. Lastly, we observed morpho-functional convergences among several mammalian taxa and detected some taxa that achieve similar locomotor features following different morphological paths.

Seasonal differences in foraging dynamics, habitat use and home range size of Wahlberg’s epauletted fruit bat in an urban environment

Urbanization through the process of habitat loss and fragmentation affects ecosystems. Many species are no longer able to survive in these urban areas; however, there are some that have been able to persist and even thrive in these habitats. One such species is Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi). Little is known about its existence in urban areas. Consequently we studied their seasonal variation in home range size, movements and foraging dynamics in the urban environment of Pietermaritzburg, South Africa. In a pilot study in summer, adult fruit bats (n = 8) were caught, fitted with radio-transmitters, and their movements followed for 12 nights and days. Although their movements varied considerably, no bats left the urban environment. Some of the larger distances covered in a single night were 2 and 5 km. In winter, an additional ten adult fruit bats were caught and fitted with radio-transmitters. Movements were followed for three weeks during winter and spring respectively. Winter home range size was greater than spring home range size. During winter the bats fed mostly on syringa fruits (Melia azedarach), an alien invasive, while their diet in spring was more varied and included species of indigenous and exotic fruits. The reduced variety of fruit eaten in winter may be explained by a reduction in fruiting plant species, and thus a reliance on a few species to meet their dietary requirements. The bats would have a role in seed dispersal but therein lies the problem of them also dispersing invasive plants. Further research is needed to assess the role played by exotic and alien plant species in the continued success of urban wildlife, in particular fruit bats. The seasonal variation in home range size gives insight into the urban movements of Wahlberg’s epauletted fruit bats. The use of exotic and invasive plants by these bats is also significant.

Seasonal Differences in Foraging Dynamics, Habitat Use and Home Range Size of Wahlberg's Epauletted Fruit Bat in an Urban Environment

Urbanization through the process of habitat loss and fragmentation affects ecosystems. Many species are no longer able to survive in these urban areas; however, there are some that have been able to persist and even thrive in these habitats. One such species is Wahlberg's epauletted fruit bat (Epomophorus wahlbergi). Little is known about its existence in urban areas. Consequently we studied their seasonal variation in home range size, movements and foraging dynamics in the urban environment of Pietermaritzburg, South Africa. In a pilot study in summer, adult fruit bats (n = 8) were caught, fitted with radio-transmitters, and their movements followed for 12 nights and days. Although their movements varied considerably, no bats left the urban environment. Some of the larger distances covered in a single night were 2 and 5 km. In winter, an additional ten adult fruit bats were caught and fitted with radio-transmitters. Movements were followed for three weeks during winter and spring respectively. Winter home range size was greater than spring home range size. During winter the bats fed mostly on syringa fruits (Melia azedarach), an alien invasive, while their diet in spring was more varied and included species of indigenous and exotic fruits. The reduced variety of fruit eaten in winter may be explained by a reduction in fruiting plant species, and thus a reliance on a few species to meet their dietary requirements. The bats would have a role in seed dispersal but therein lies the problem of them also dispersing invasive plants. Further research is needed to assess the role played by exotic and alien plant species in the continued success of urban wildlife, in particular fruit bats. The seasonal variation in home range size gives insight into the urban movements of Wahlberg's epauletted fruit bats. The use of exotic and invasive plants by these bats is also significant.

Effective sociodemographic population assessment of elusive species in ecology and conservation management.

Wildlife managers are urgently searching for improved sociodemographic population assessment methods to evaluate the effectiveness of implemented conservation activities. These need to be inexpensive, appropriate for a wide spectrum of species and straightforward to apply by local staff members with minimal training. Furthermore, conservation management would benefit from single approaches which cover many aspects of population assessment beyond only density estimates, to include for instance social and demographic structure, movement patterns, or species interactions. Remote camera traps have traditionally been used to measure species richness. Currently, there is a rapid move toward using remote camera trapping in density estimation, community ecology, and conservation management. Here, we demonstrate such comprehensive population assessment by linking remote video trapping, spatially explicit capture–recapture (SECR) techniques, and other methods. We apply it to three species: chimpanzees Pan troglodytes troglodytes, gorillas Gorilla gorilla gorilla, and forest elephants Loxodonta cyclotis in Loango National Park, Gabon. All three species exhibited considerable heterogeneity in capture probability at the sex or group level and density was estimated at 1.72, 1.2, and 1.37 individuals per km2 and male to female sex ratios were 1:2.1, 1:3.2, and 1:2 for chimpanzees, gorillas, and elephants, respectively. Association patterns revealed four, eight, and 18 independent social groups of chimpanzees, gorillas, and elephants, respectively: key information for both conservation management and studies on the species' ecology. Additionally, there was evidence of resident and nonresident elephants within the study area and intersexual variation in home range size among elephants but not chimpanzees. Our study highlights the potential of combining camera trapping and SECR methods in conducting detailed population assessments that go far beyond documenting species diversity patterns or estimating single species population size. Our study design is widely applicable to other species and spatial scales, and moderately trained staff members can collect and process the required data. Furthermore, assessments using the same method can be extended to include several other ecological, behavioral, and demographic aspects: fission and fusion dynamics and intergroup transfers, birth and mortality rates, species interactions, and ranging patterns.

Home range size variation in female arctic grizzly bears relative to reproductive status and resource availability.

The area traversed in pursuit of resources defines the size of an animal’s home range. For females, the home range is presumed to be a function of forage availability. However, the presence of offspring may also influence home range size due to reduced mobility, increased nutritional need, and behavioral adaptations of mothers to increase offspring survival. Here, we examine the relationship between resource use and variation in home range size for female barren-ground grizzly bears (Ursus arctos) of the Mackenzie Delta region in Arctic Canada. We develop methods to test hypotheses of home range size that address selection of cover where cover heterogeneity is low, using generalized linear mixed-effects models and an information-theoretic approach. We found that the reproductive status of female grizzlies affected home range size but individually-based spatial availability of highly selected cover in spring and early summer was a stronger correlate. If these preferred covers in spring and early summer, a period of low resource availability for grizzly bears following den-emergence, were patchy and highly dispersed, females travelled farther regardless of the presence or absence of offspring. Increased movement to preferred covers, however, may result in greater risk to the individual or family.

Home range size variation in a recovering wolf population: evaluating the effect of environmental, demographic, and social factors

Home range size in mammals is a key ecological trait and an important parameter in conservation planning, and has been shown to be influenced by ecological, demographic and social factors in animal populations. Information on space requirements is especially important for carnivore species which range over very large areas and often come into direct conflict with human interest. We used long-term telemetry-location data from a recovering wolf population in Scandinavia to investigate variation in home range size in relation to environmental and social characteristics of the different packs. Wolves showed considerable variation in home range size, which ranged from 259 to 1,676 km(2). Although wolf density increased fourfold during the study period, we found no evidence that intraspecific competition influenced range size. Local variation in moose density, which was the main prey for most packs, did not influence wolf home range size. Home ranges increased with latitude and elevation and decreased with increased roe deer density. Although prey biomass alone did not influence range size, our data suggest that there is a correlation between habitat characteristics, choice of prey species and possible hunting success, which currently combine to shape home range size in Scandinavian wolves.

Home range, activity and sociality of a top predator, the dingo: a test of the Resource Dispersion Hypothesis

The idea that groups of individuals may develop around resource patches led to the formulation of the Resource Dispersion Hypothesis (RDH). We tested the predictions of the RDH, within a quasi‐experimental framework, using Australia’s largest terrestrial predator, the dingo Canis lupus dingo. Average dingo group sizes were higher in areas with abundant focal food sources around two mine sites compared with those in more distant areas. This supports the notion that resource richness favours larger group size, consistent with the RDH. Irrespective of season or sex, average home range estimates and daily activity for dingoes around the mine sites were significantly less than for dingoes that lived well away. Assuming that a territory is the defended part of the home range and that territory size is correlated with home range size, consistent with the RDH, the spatial dispersion of food patches therefore determined territory size for dingoes in our study. However, although sample size was small, some dingoes that accessed the supplementary food resource at the mines also spent a large proportion of their time away, suggesting a breakdown of territorial defence around the focal food resource. This, in combination with the large variation in home range size among dingoes that accessed the same supplementary food resource, limits the predictive capabilities of the RDH for this species. We hypothesize that constraints on exclusive home range occupancy will arise if a surfeit of food resources (in excess of requirements for homeostasis) is available in a small area, and that this will have further effects on access to mates and social structure. We present a conceptual model of facultative territorial defence where focal resources are available to demonstrate our findings.

Factors affecting intraspecific variation in home range size of a large African herbivore

Factors affecting intraspecific variation in home range size have rarely been examined using modern statistical and remote sensing methods. This is especially true for animals in seasonal savanna environments in Africa, despite this biome’s importance for both conservation and development goals. We studied the impacts of spatial and temporal variability in environmental conditions, along with individual and social factors, on home range sizes in African buffalo (Syncerus caffer) in northeastern Namibia. Our data set spans 4 years, is derived from 32 satellite tracking collars, and contains over 35,000 GPS locations. We used the local convex hull method to estimate home range size from 31 buffalo captured at 6 sites. We used a variety of remotely sensed data to characterize potential anthropogenic and natural boundaries, as well as seasonal and temporal heterogeneity in environmental conditions. Using an information-theoretic, mixed effects approach, our analyses showed that home ranges varied over two orders of magnitude and are among the largest recorded for this species. Variables relating to vegetation and habitat boundaries were more important than abiotic environmental conditions and individual or social factors in explaining variation in home range size. The relative contributions of environmental, individual, social, and linear boundary variables to intraspecific home range size have rarely been examined and prior to this had not been assessed for any species in seasonal savannas of Africa. Understanding the factors that condition space-use patterns of wildlife in this area will lead to better-informed conservation and sustainable development decisions.

Landscape composition weakly affects home range size in Blanding's turtles (Emydoidea blandingii)

Landscape composition and habitat quality influence the abundance, population structure, and movements of animals. Understanding how an animal interacts with elements of the landscape helps predict its response to habitat loss and changes in land cover. We tested the hypothesis that the extent of movement depends on landscape composition in a threatened freshwater turtle, Emydoidea blandingii We measured habitat composition at multiple spatial scales, ranging from the home range to the landscape scale. We built multiple linear regression models to predict home range size from the proportional use of 5 land-use categories, while controlling for intrinsic factors (sex, body size). We found that landscape composition significantly influenced home range size in the Blanding's turtle; however, the models explained a low proportion of the observed variation in home range size, meaning that landscape composition had a weak effect on movement. Our results also suggest that sex and body size have little influence on home range size in Blanding's turtles. More research is needed to determine the factors driving movement in this species, and overall, we recommend cautious use of models predicting space use as a function of landscape composition in a conservation context.

Interannual home range variation, territoriality and overlap in breeding Bonelli’s Eagles (Aquila fasciata) tracked by GPS satellite telemetry

Animal movement patterns and use of space depend upon environmental resources (i.e., food availability), and on conspecific and interspecific interactions. We studied the home range of seven territorial Bonelli’s Eagles (Aquila fasciata) tracked by GPS satellite telemetry over a period of 4–5 years to determine home range characteristics and annual and individual variations. Bonelli’s Eagles hold an annual home range of Minimum Convex Polygon (MCP) = 205.6 km2 (range 44.7–704.8 km2) and Kernel 95 % = 44.4 km2 (range 31.8–91.9 km2). Eagles showed slight temporal variation in home range sizes, but a wide variation in use of space. Only 27.3 % of the accumulated home range was used during all seasons, while 30.3 % was used only during a single season. Areas around the nest, main hunting areas and roosting sites were utilised regularly every year in both breeding and non-breeding seasons. Accumulated home ranges were stabilised in year 3 of monitoring. Individuals displayed strong territoriality, even in non-breeding seasons, although eagles also made long trips (>15 km) well beyond their territorial boundaries, as assessed for the first time by GPS satellite telemetry. The overlap was slight for two adjacent pairs. In addition, we noticed a strong relationship between topographical landmarks and home range segregation. This study reinforces the idea that combining information on season patterns, conspecific distribution and topography can help define both the shape and size of home ranges more realistically.

Troop Size and Human‐Modified Habitat Affect the Ranging Patterns of a Chacma Baboon Population in the Cape Peninsula, South Africa

Differences in group size and habitat use are frequently used to explain the extensive variability in ranging patterns found across the primate order. However, with few exceptions, our understanding of primate ranging patterns stems from studies of single groups and both intra- and inter-specific meta-analyses. Studies with many groups and those that incorporate whole populations are rare but important for testing socioecological theory in primates. We quantify the ranging patterns of nine chacma baboon troops in a single population and use Spearman rank correlations and generalized linear mixed models to analyze the effects of troop size and human-modified habitat (a proxy for good quality habitat) on home range size, density (individuals/km(2) ), and daily path length. Intrapopulation variation in home range sizes (1.5-37.7 km(2) ), densities (1.3-12.1 baboons/km(2) ), and daily path lengths (1.80-6.61 km) was so vast that values were comparable to those of baboons inhabiting the climatic extremes of their current distribution. Both troop size and human-modified habitat had an effect on ranging patterns. Larger troops had larger home ranges and longer daily path lengths, while troops that spent more time in human-modified habitat had shorter daily path lengths. We found no effect of human-modified habitat on home range size or density. These results held when we controlled for the effects of both a single large outlier troop living exclusively in human-modified habitat and baboon monitors on our spatial variables. Our findings confirm the ability of baboons, as behaviorally adaptable dietary generalists, to not only survive but also to thrive in human-modified habitats with adjustments to their ranging patterns in accordance with current theory. Our findings also caution that studies focused on only a small sample of groups within a population of adaptable and generalist primate species may underestimate the variability in their respective localities.

Dynamics in space use of American mink (Neovison vison) in a fishpond area in Northern Germany

Telemetry of American mink Neovison vison revealed seasonal and sexual variations in home-range size, intersexual- and partially intrasexual range overlaps and spatial dynamic of territorial system. From 2003 to 2006, 14 mink (nine males and five females) were radio-tracked in a fishpond area in northern Germany. We observed comparatively large home ranges. Both sexes reduced their large summer home ranges to smaller ones in the winter period. In both seasons, male mink used significantly larger areas than female mink. During the mating season, males considerably enlarged their home ranges and roamed nearly through the entire study area. These variations and diversity of range size were discussed in connection with thermoregulatory behaviour, prey availability and distribution, population density and stability of the social system. Analysing intraspecific static interactions, we observed high intersexual overlapping rates in both the summer and winter periods. But there were no or rather very low levels of intrasexual overlapping. However, in the summer period, large home ranges of neighbouring males also overlapped to some extent, but temporal avoidance of adjacent territory holders was observed. Consequently, our results reveal intrasexual territoriality, with males having larger territories, overlapping those of females. The shifting of stable temporary home ranges observed within one season or between the same seasons of consecutive years demonstrates the highly dynamic nature of spatial behaviour among American mink. All these recorded characteristic features of spatial behaviour should be considered when planning mink control projects and measures for the management of this invasive carnivore.

Movements and Habitat Use of Eastern Foxsnakes (Pantherophis gloydi) in Two Areas Varying in Size and Fragmentation

Determining how animals respond to habitat loss and fragmentation requires detailed studies of habitat use and behavior in regions that vary in their degree of fragmentation. As predators, snakes are an important component of ecosystems, yet little is known about how they respond behaviorally to habitat loss. Using radiotelemetry at two locations that differ in their habitat patch size, we examined habitat-use patterns at two spatial scales and movement patterns for the endangered Eastern Foxsnake (Phantherophis gloydi). Movement patterns were similar at the two locations, but individuals exhibited greater variation in home-range size, and males and gravid females dispersed further from hibernation sites within the larger natural habitat patch. Individuals from both locations preferred marsh at the home-range scale, but open dry habitat at the location scale. Within the smaller habitat patch, however, these preferences were accentuated with snakes avoiding agricultural fields. At the landscape scale, individual occurrence records were found closer to, and in areas with a higher density of, usable habitat than locations that are distributed randomly.

Toward an Identification of Resources Influencing Habitat Use in a Multi-Specific Context

Interactions between animal behaviour and the environment are both shaping observed habitat use. Despite the importance of inter-specific interactions on the habitat use performed by individuals, most previous analyses have focused on case studies of single species. By focusing on two sympatric populations of large herbivores with contrasting body size, we went one step beyond by studying variation in home range size and identifying the factors involved in such variation, to define how habitat features such as resource heterogeneity, resource quality, and openness created by hurricane or forest managers, and constraints may influence habitat use at the individual level. We found a large variability among individual's home range size in both species, particularly in summer. Season appeared as the most important factor accounting for observed variation in home range size. Regarding habitat features, we found that (i) the proportion of area damaged by the hurricane was the only habitat component that inversely influenced roe deer home range size, (ii) this habitat type also influenced both diurnal and nocturnal red deer home range sizes, (iii) home range size of red deer during the day was inversely influenced by the biomass of their preferred plants, as were both diurnal and nocturnal core areas of the red deer home range, and (iv) we do not find any effect of resource heterogeneity on home range size in any case. Our results suggest that a particular habitat type (i.e. areas damaged by hurricane) can be used by individuals of sympatric species because it brings both protected and dietary resources. Thus, it is necessary to maintain the openness of these areas and to keep animal density quite low as observed in these hunted populations to limit competition between these sympatric populations of herbivores.

Evolutionarily stable consumer home range size in relation to resource demography and consumer spatial organization

There is a large variation in home range size within species, yet few models relate that variation to demographic and life-history traits. We derive an approximate deterministic population dynamics model keeping track of spatial structure, via spatial moment equations, from an individual-based spatial consumer-resource model; where space-use of consumers resembles that of central place foragers. Using invasion analyses, we investigate how the evolutionarily stable home range size of the consumer depends on a number of ecological and behavioral traits of both the resource and the consumer. We show that any trait variation leading to a decreased overall resource production or an increased spatial segregation between consumer and resource acts to increase consumer home range size. In this way, we extend theoretical predictions on optimal territory size to a larger range of ecological scenarios where home ranges overlap and population dynamics feedbacks are possible. Consideration of spatial traits such as dispersal distances also generates new results: (1) consumer home range size decreases with increased resource dispersal distance, and (2) when consumer agonistic behavior is weak, more philopatric consumers have larger home ranges. Finally, our results emphasize the role of the spatial correlation between consumer and resource distributions in determining home range size, and suggest resource dispersion is less important.

Multiyear Home-Range Ecology of Common Side-blotched Lizards in Eastern Oregon with Additional Analysis of Geographic Variation in Home-range Size

We studied the spatial ecology of Common Side-blotched Lizards (Uta stansburiana) in the northern Great Basin desert of eastern Oregon. Over 3 yr (2007–2009) we collected 3675 coordinates from 51 males and 60 females during the breeding season (mid-May to early July). We found significant variation among years and between the sexes in home-range size, but contrasting evidence for a relationship between body size and home-range size. Lizard home ranges overlapped those of other lizards extensively and the number of overlapping home ranges within and between the sexes as well as the percentage of unique home range varied among study years. However, we found no evidence that lizards are minimizing their overlaps with the same sex and maximizing their overlaps with the opposite sex. By studying home ranges over multiple years we found that lizards exhibit strong year-to-year fidelity in home-range location, which may be a consequence of relatively high interannual survival. We also present long-term data on the home ranges of Common Side-blotched Lizards from a population in central California that were studied for 8 (females) or 10 (males) consecutive yr as well as new analyses of Tinkle's (1967a,b) 6-yr dataset from west Texas. We found that winter rainfall, population density, and lizard sex were significant predictors of home-range size across years within both sites, though the effects of density and sex appear to be more robust than rainfall. By combining data on home-range ecology from nine study populations of Uta stansburiana, we tested for the effects of latitude of origin, rainfall, population density, and lizard sex on home-range size across the geographic distribution of this species. Similar to our results within sites, rainfall, density, and sex have significant effects on home-range size when comparing sites, but again the effects of density and sex appear to be more robust than rainfall. Latitude of origin also appears to explain variation in home-range size independent of ecosystem productivity (i.e., rainfall, density). Thus, we conclude that ecosystem productivity is an important determinant of density and spatial ecology of lizard populations and that even modest fluctuations in productivity may influence population density and home-range ecology, but that latitude of origin remains important independent of these factors.

Effects of landscape and land‐ownership patterns on deer movements in a suburban community

AbstractWhite‐tailed deer (Odocoileus virginianus) have adapted to, and are thriving in, residential–suburban landscapes. Special hunts, sharpshooting programs, and fertility control efforts have been implemented in residential communities to reduce local deer populations. For these management strategies to be effective, it is important to understand deer movement and behavior patterns in suburban landscapes. Our objectives were to quantify annual and hunt‐season home‐range size, and evaluate the relationships between landscape characteristics, land‐ownership patterns, and deer movements during the autumn hunting season. Much variation in home range size was observed for annual (15.5–173 ha) and hunt‐season home range (16.8–120.7 ha) over the 2‐yr study. Deer core areas were not characteristically different from home ranges with regards to forest lands or building density, but were different with regards to road density and property density. Deer use of core areas during the day was similar to, or higher than, deer use at night. Most individual properties in deer core areas were <2.8 ha. Under the current set‐back distance for firearms hunting (152 m), 31% and 38% of deer had no portion of their home range potentially open to firearms hunting, and 69% and 81% had no portion of their core areas potentially open to firearms hunting in years 1 and 2. Percentage of forest in home range buffers decreased from 66% in year 1 (abundant acorns) to 46% in year 2 (moderate acorns) as deer shifted into residential development. Findings from our study emphasize the value of conducting multiyear studies and incorporating other variables such as mast abundance to improve interpretation of landscape models. The close association of deer core areas with roads suggests that sharpshooting programs that bait and shoot deer from roads may be an effective management option. In suburban landscapes, deer core areas are comprised of many different landowners, limiting hunter access and mobility to deer core areas. No‐hunt buffers around buildings should be reduced to levels that increase hunter access to deer core areas, yet maintain reasonable safety zones. © 2011 The Wildlife Society.

What determines variation in home range size across spatiotemporal scales in a large browsing herbivore?

1. Most studies of intraspecific variation in home range size have investigated only a single or a few factors and often at one specific scale. However, considering multiple spatial and temporal scales when defining a home range is important as mechanisms that affect variation in home range size may differ depending on the scale under investigation. 2. We aim to quantify the relative effect of various individual, forage and climatic determinants of variation in home range size across multiple spatiotemporal scales in a large browsing herbivore, the moose (Alces alces), living at the southern limit of its distribution in Norway. 3. Total home range size and core home range areas were estimated for daily to monthly scales in summer and winter using both local convex hull (LoCoH) and fixed kernel home range methods. Variance in home range size was analysed using linear mixed-effects models for repeated measurements. 4. Reproductive status was the most influential individual-level factor explaining variance in moose home range size, with females accompanied by a calf having smaller summer ranges across all scales. Variation in home range size was strongly correlated with spatiotemporal changes in quantity and quality of natural food resources. Home range size decreased with increasing browse density at daily scales, but the relationship changed to positive at longer temporal scales. In contrast, browse quality was consistently negatively correlated with home range size except at the monthly scale during winter when depletion of high-quality forage occurs. Local climate affected total home range size more than core areas. Temperature, precipitation and snow depth influenced home range size directly at short temporal scales. 5. The relative effects of intrinsic and extrinsic determinants of variation in home range size differed with spatiotemporal scale, providing clear evidence that home range size is scale dependent in this large browser. Insight into the behavioural responses of populations to climatic stochasticity and forage variability is essential in view of current and future climate change, especially for populations with thermoregulatory restrictions living at the southern limit of their distribution.

Range Expansion as a Response to Increasing Group Size in the Yunnan Snub-Nosed Monkey

The Yunnan snub-nosed monkey (Rhinopithecus bieti) is characterized by a larger home range and group size than other colobine species. We investigated variations in home range size of a free-ranging group of R. bieti from 1998 to 2007 in the Baimaxueshan National Nature Reserve in Yunnan, China. Group size increased from 160 to 450 over the 10 years. Results also showed a home range shift and yearly home range expansion, although this expansion was very limited. The study group covered a 33.78-km² area during the 10-year period, with some areas abandoned and others used repeatedly. The yearly home range increase stopped in 2004 and decreased thereafter. Despite increasing group size usually being coupled with larger yearly home range (>30 km²), the group confined itself within a relatively small and stable area (<18 km²) during 2005–2007, with a significant portion of their accessible home range discarded. Consequently, the study group showed the highest recorded population density among extant groups of R. bieti. Reasons why the group settled into a substantially smaller home range area remain unclear.

Intra- and interspecific variation in home-range size in sympatric tuco-tucos, Ctenomys australis and C. talarum

Despite the fundamental nature of the home range to the biology of a species, aspects of its size, shape, and structure are not well defined in certain groups, such as subterranean rodents. These rodents, characterized by limited individual mobility and a patchy distribution of local populations, generally defend multipurpose territories in which breeding and foraging take place, increasing the chances for trade-offs among factors of habitat quality. The present study assessed the home-range size and shape of 2 species of tuco-tucos, Ctenomys australis (300–600 g) and C. talarum (100–180 g), using radiotelemetry in an area where they occur in sympatry, and explored the factors that could influence space use in these subterranean rodents. Home-range size (95% adaptive kernel) of C. australis (1,282.22 6 1,014.83 m 2 ) was ,19-fold larger than that of C. talarum (66.69 6 22.34 m 2 ). The area covered daily by C. australis represented only about 9% of the total home-range size estimated by radiotelemetry in this study and was almost twice as large as that of C. talarum, but the area covered by the latter species represented an average of 35% of its total home-range size. Total aerial and subterranean plant biomass, plant cover, and soil hardness were significantly higher in the habitat occupied by C. talarum. Contrary to expectation, body size was not the predominant factor explaining intra- and interspecific variation in home-range size. We discuss how variation in food availability in space and time and differences in the intensity of polygyny could be more important factors shaping home-range size in this genus of subterranean rodents. DOI: 10.1644/10-MAMM-A-057.1.