Predictors Of Home Range Size Research Articles

Aggressive behavior as a predictor of home range size: findings from both range-restricted and widespread Darwin’s finch species

AbstractInformation about an animal’s home range (the geographical area in which it accesses resources for survival and reproduction) is vital broadly for understanding animal behavior and specifically for developing conservation management plans. Although personality traits—consistent individual differences in behavior across time and contexts—may affect an animal’s home range size, we still lack a breadth of empirical studies across systems to fully appreciate this influence. Here, we tested the relationship between behavioral responses and home range size in two Darwin’s finch species on Floreana Island: the critically endangered and range-restricted Medium Tree Finch (Camarhynchus pauper) and the common and widespread Small Ground Finch (Geospiza fuliginosa). Using a combination of rapid-assessment assays during both short-term captivity and in the field, we measured exploration and aggressiveness in males from both species. We then used radio telemetry to measure each bird’s home range size over a week-long period. We predicted that (1) fast-exploring individuals would have larger home ranges, and (2) more aggressive individuals would have smaller home ranges. We found that Medium Tree Finches had smaller home ranges than Small Ground Finches, that exploratory behavior was positively correlated with home range size only in Small Ground Finches, and that, in both species, individuals’ aggressiveness was negatively correlated with home range size, whereby the more aggressive individuals occupied smaller home ranges. We conclude that behavioral responses that align with major personality traits can predict home range size, which may provide an important tool for the conservation and management of endangered species when, for example, selecting individuals with different personality profiles for reintroduction.

Climate, Temporal Abundance of Key Food Sources and Home Ranges of Crested Macaques (Macaca nigra) in Sulawesi, Indonesia: A Longitudinal Phenological Study

Climate change is associated with more frequent extreme weather conditions and an overall increase in temperature around the globe. Its impact on individual ecosystems is not yet well known. Long-term data documenting climate and the temporal abundance of food for primates are scarce. We used long-term phenological data to assess climate variation, fruit abundance and home range sizes of the endemic and Critically Endangered crested macaques (Macaca nigra) in Tangkoko forest, Sulawesi, Indonesia. Between January 2012 and July 2020, every month, we monitored 498 individual trees from 41 species and 23 families. We noted each tree’s phenophase and assessed variation in climate (daily temperature and rainfall) and fruit abundance. We also investigated whether individual trees of known key food sources for macaques (New Guinea walnut trees, Dracontomelon spp, two species, N = 10 individual trees; fig trees, Ficus spp, four species, N = 34, and spiked peppers, Piper aduncum, N = 4) showed regular and synchronised fruiting cycles. We used 2877 days of ranging data from four habituated groups to estimate home ranges between January 2012 and July 2020. We created models to evaluate the impact of ecological factors (temperature, rainfall, overall fruit abundance, fig abundance). We found that the temperature increased in Tangkoko forest, and the overall fruit abundance decreased across the study. Top key fruits showed different trends in fruiting. Figs seem to be present year-round, but we did not detect synchrony between individuals of the same species. The macaque home ranges were about 2 km2. Monthly temperature was the main predictor of home range size, especially in disturbed forest with previously burnt areas. This information will help to further monitor changes in the macaques’ habitat, and better understand ranging and foraging strategies of a Critically Endangered species and hence contribute to its conservation.

Precipitation, vegetation productivity, and human impacts control home range size of elephants in dryland systems in northern Namibia.

Climatic variability, resource availability, and anthropogenic impacts heavily influence an animal's home range. This makes home range size an effective metric for understanding how variation in environmental factors alter the behavior and spatial distribution of animals. In this study, we estimated home range size of African elephants (Loxodonta africana) across four sites in Namibia, along a gradient of precipitation and human impact, and investigated how these gradients influence the home range size on regional and site scales. Additionally, we estimated the time individuals spent within protected area boundaries. The mean 50% autocorrelated kernel density estimate for home range was 2200 km2 [95% CI:1500–3100 km2]. Regionally, precipitation and vegetation were the strongest predictors of home range size, accounting for a combined 53% of observed variation. However, different environmental covariates explained home range variation at each site. Precipitation predicted most variation (up to 74%) in home range sizes (n = 66) in the drier western sites, while human impacts explained 71% of the variation in home range sizes (n = 10) in Namibia's portion of the Kavango‐Zambezi Transfrontier Conservation Area. Elephants in all study areas maintained high fidelity to protected areas, spending an average of 85% of time tracked on protected lands. These results suggest that while most elephant space use in Namibia is driven by natural dynamics, some elephants are experiencing changes in space use due to human modification.

An unexpected backyard hunter: breeding Barred Owls exhibit plasticity in habitat selection along a development gradient

Despite extensive accounts in the literature describing Barred Owls (Strix varia) as obligate forest-interior species, Barred Owls have increasingly been observed in urbanized landscapes. To determine if certain habitat characteristics, such as mature urban trees, facilitate the occurrence of Barred Owls in developed regions, we deployed GPS transmitters on 20 breeding Barred Owls in northwestern South Carolina. We selected territories containing a gradient of development density and habitat types to examine predictors of home range size and habitat selection along an urban-rural gradient. We related nocturnal locations to habitat features using resource selection functions (RSFs). We explored differential use along a development gradient by modeling interactions between habitat parameters and measures of development in the home range. Home range size varied from 0.38 km2 to 3.38 km2; size increased with the percentage of treeless area in the territory such as agricultural fields and power lines. Distance to nest, tree height, and distance to canopy edge were the most important predictors of owl use. Barred Owl selection for roadsides and aquatic features increased with degree of fragmentation in the home range. This is the first resource selection study using GPS data to examine habitat use of Barred Owls in the context of development. Our results highlight the behavioral plasticity of a species previously described as sensitive to anthropogenic impacts. The presence of this large avian predator in urban forests suggests that retaining key habitat features can promote multi-trophic communities even when other aspects of the habitat are highly altered.

Common Cuckoo home ranges are larger in the breeding season than in the non-breeding season and in regions of sparse forest cover

Knowledge of species’ habitat requirements can be gained from studying individual variation in home range size, under the assumption that larger home ranges reflect increased resource needs or decreased habitat quality. We used satellite telemetry to delineate home ranges of South Scandinavian Common Cuckoos (Cuculus canorus) throughout their annual cycle. Annual stage (breeding or non-breeding period) and percentage of forest cover were good predictors of home range size. Average breeding season home ranges were ten times as large as those of non-breeding home ranges, suggesting strong temporal variation in the birds’ resource needs, and perhaps lower habitat quality in the breeding range compared to the African part of their annual range. Furthermore, although the Cuckoos rarely chose a home range with complete forest cover, we found a significant negative relationship between forest cover and home range area. This suggests that heterogeneous landscapes which include some dense forest cover constitute important habitat for Cuckoos, and that the continuing trend of forest loss in tropical Africa could reduce habitat quality for the Cuckoo in the non-breeding season.

Home range characteristics of a subordinate predator: selection for refugia or hunt opportunity?

AbstractCougars Puma concolor are described as ‘habitat generalists’, but little is known about which ecological factors drive their home range selection. For example, how do resource distributions and inter‐species competition with dominant competitors (i.e. wolves, Canis lupus) over such resources, influence the distributions of cougars on the landscape? We tracked cougars using Very High Frequency (VHF; 2001 to 2005) and Global Positioning System (GPS; 2006 to 2011) technology in the Southern Yellowstone Ecosystem (SYE) in northwestern Wyoming, USA. We tested whether data type (VHF vs. GPS), cougar sex, access to forests (refugia) or hunt opportunity explained the size of 50% and 95% kernel density estimator (KDE) home ranges. Second, we quantified attributes of cougar home ranges and tested whether they were different from attributes of the overall study area, to address the ecological question: Do cougars select home ranges based on the availability of refugia, hunt opportunity or some combination of the two? Cougar sex and data type proved significant predictors of home range size for both 95% and 50% KDEs, and the amount of forest partly explained the size of 50% KDEs. Cougar home ranges derived from VHF data were 1.4–1.9 times larger than home ranges derived from GPS data; however, home range attributes determined from VHF and GPS data were remarkably equivalent. Female cougars selected home ranges with higher hunt opportunity than males, supporting the assumption that females primarily select home ranges with suitable prey to sustain themselves and their young. All cougars selected home ranges further from known wolf packs, providing evidence for newly established competition between resident cougars and recolonizing wolves, but did not select home ranges with greater access to landscape refugia. Our results provided evidence that cougars in the SYE select home ranges that provide high hunting opportunity and a spatial buffer that mitigates potential conflicts with a dominant competitor.

Evolutionary predictors of mammalian home range size: body mass, diet and the environment

AbstractAimMammalian home range patterns provide information on spatial behaviour and ecological patterns, such as resource use, that is often used by conservation managers in a variety of contexts. However, there has been little research on home range patterns outside of the terrestrial environment, potentially limiting the relevance of current home range models for marine mammals, a group of particular conservation concern. To address this gap, we investigated how variation in mammalian home range size among marine and terrestrial species was related to diet, environment and body mass.LocationGlobal.MethodsWe compiled data on home range size, environment (marine and terrestrial), diet and body mass from the literature and empirical studies to obtain a dataset covering 462 mammalian species. We then used phylogenetic regression analyses (to address non‐independence between species) to examine the relative contribution of these factors to variation of home range size among species.ResultsBody size explained the majority of the difference in home range size among species (53–85%), with larger species occupying larger home ranges. The type of food exploited by species was also an important predictor of home range size (an additional 15% of variation), as was the environment, but to a much lesser degree (1.7%).Main conclusionsThe factors contributing to the evolution of home ranges are more complex than has been assumed. We demonstrate that diet and body size both influence home range patterns but differ in their relative contribution, and show that colonization of the marine environment has resulted in the expansion of home range size. Broad‐scale models are often used to inform conservation strategies. We propose that future integrative models should incorporate the possibility of phylogenetic effects and a range of ecological variables, and that they should include species representative of the diversity within a group.

Drivers of home range characteristics across spatiotemporal scales in a Neotropical primate, Cebus capucinus

The factors that drive within-species variation in animal space use remain poorly understood. A growing body of evidence suggests that both home range attributes and biological interpretations of the home range may depend fundamentally on the scale of analysis. We utilize a multiscale mixed effects modelling framework to examine how seasonal fluctuations in climate, food resource abundance and group mass affect variance in home range area and the maturity stage of forest used by a group-living Neotropical primate, the white-faced capuchin, Cebus capucinus. Using an 8-year data set representing over 20 000 contact hours, we estimated home ranges for seven social groups at four nested temporal scales and three nested spatial scales using a movement-based kernel method. Group mass was consistently the most important predictor of home range size in our models, and its effects were relatively insensitive to spatial or temporal scale. Mean daily maximum temperature was an influential factor in shaping monthly range area and composition, with hotter weather favouring smaller home range size and increased use of mature evergreen forest. Greater fruit availability was also associated with smaller monthly range area. The effects of temperature and fruit availability were both scale dependent: the impact of both variables was greatest on the core zone. The different study groups showed marked variation in the habitat composition of their home ranges, but in all groups, higher-use zones consisted of older, more evergreen forest. Our study illustrates the complex ecological processes that affect movement behaviour in a Neotropical primate across a range of spatial and temporal scales, highlighting the importance of group mass, climatic seasonality, landscape heterogeneity and dietary shifts in shaping the home range.

HOME-RANGE SIZE AND SPACING PATTERNS OF MACROPHYLLUM MACROPHYLLUM (PHYLLOSTOMIDAE) FORAGING OVER WATER

We studied home-range size and patterns of range use of long-legged bats, Macrophyllum macrophyllum (Phyllostomidae), at Barro Colorado Nature Monument, Panama, by using radiotelemetry. Movements of 4 males and 5 females fitted with radiotransmitters were monitored for 4–7 entire nights each between April and July 2002. M. macrophyllum had an extensive range compared to other similar-sized phyllostomid bats. Median home-range size for the 9 individuals tracked was 23.9 ha (range 7.3–150.7 ha). With a median of 17.3 ha (range = 7.3–24.9 ha), home ranges of males were somewhat, but not significantly, smaller than those of females (44.4 ha, range = 16.3–150.7 ha). The bats foraged exclusively over water, whereby hunting activity was restricted to the immediate shoreline of Gatun Lake. Foraging areas ranged from 2.7 to 96.1 ha, with a median of 12.3 ha for both sexes. In general, there was high night-to-night consistency in the use of foraging areas. Most bats had multiple foraging and core areas. Core-use areas corresponded to approximately 35% of the bats' foraging areas and were larger in females (median = 5.3 ha, range = 1.1–54.1 ha) than in males (3.3 ha, range = 2.6–8.7 ha). Maximum range span varied from 0.5 to 7.5 km, whereby males in general and 1 tracked harem male in particular foraged much closer to the day roost than did females. Individual M. macrophyllum traveled an estimated 35–47 km on a nightly basis, and females moved significantly greater distances than did males. Our results do not provide support for the proposition that small bats typically have small home ranges. In contrast, we conclude that foraging strategy, diet, dispersion of food resources, and wing morphology are generally better predictors of home-range size. Furthermore, reproductive condition, as well as intraspecific competition linked to colony size or social status, also strongly affect the spacing behavior and movement patterns of these bats. Our results suggest that, although M. macrophyllum employs a gleaning foraging strategy, it closely parallels aerial insectivorous bats in terms of range size and movement distances.

Social influences on ranging patterns among chimpanzees (Pan troglodytes verus) in the Tai National Park, Cote d'Ivoire

Group size is expected to be an important factor to predict home-range (HR) size in social animals. In chimpanzees adult males play an important role in defending the HR against neighbors, and therefore it has been suggested that HR size depends on the number of adult males. In this long-term study on wild West African chimpanzees, we analyzed the relative importance of community size and composition on ranging patterns over a 10-year period, using multivariate statistics. Because community size decreased from 51 individuals with 6 adult males in 1992 to 22 individuals with only 1 adult male in 2001, we expected a decrease in HR size, which should be better predicted by the number of males than by community size. We further investigated the effect of fruit availability on monthly HRs over a 4-year period. As predicted, HR size decreased during the first 7 years of our study but increased during the last 3 years. Overall, the number of adult males was the best predictor of HR size, whereas fruit availability did not correlate with HR size. HR use remained stable over the entire study period, with a constant proportion of about 35% of the HR used as core area. High HR and core-area overlap values between different years indicated strong site-fidelity. Although the number of males within the community explained the decrease in HR size, the recent increase in size remains unexplained. This finding suggests that other factors such as relative fighting power of males affect HR size. Copyright 2003.

Influence of primary prey on home-range size and habitat-use patterns of northern spotted owls (Strix occidentalis caurina)

Correlations between the home-range size of northern spotted owls (Strix occidentalis caurina) and proportion of their range in old-growth forest have been reported, but there are few data on the relationship between their home-range size and prey. The primary prey of spotted owls are wood rats and northern flying squirrels (Glaucomys sabrinus). Wood rats are larger and heavier than flying squirrels, and their population densities tend to be much greater than those of flying squirrels. We present data indicating that the home ranges of spotted owls are smaller where their diet consists predominantly of wood rats than where it consists predominantly of flying squirrels, and the proportion of the diet consisting of wood rats and flying squirrels explained significant variation in home-range size. We also found a significant correlation between home-range size and abundance of wood rats. These data indicate that prey species are a better predictor of home-range size than the proportion of older forest within spotted owl home ranges in the Klamath Province of northwestern California and southwestern Oregon, an area that is predominantly late-successional forest. Differences in habitat use were also related to prey species. Where spotted owls foraged for wood rats, the results indicated a preference for habitat edges, but where they utilized flying squirrels no such patterns were apparent.