Home Range Estimates Research Articles

Factors influencing Arctic brown bear annual home range sizes and limitations of home range analyses

Home range size is a basic ecological index related to individual's realized niche. Its size can be influenced by body size, sex, maternal status, population density, habitat productivity, spatiotemporal variation of resources, climate, predation risk, and disturbance. Home range estimation can also be greatly affected by methodology and sampling regime. We used Global Positioning System collar data to assess what factors influenced the size of annual home ranges (space use during a single active season) of 28 female and 8 male brown bears (Ursus arctos) that denned in the Brooks Range of northcentral Alaska, USA, from 2014 to 2017. We used 2 methods to estimate annual home ranges, the Kernel Density Estimate (KDE) and the dynamic Brownian Bridge Movement Model (dBBMM). Contrary to expectations, we did not find that larger bodied bears of the same sex had larger annual home ranges. Annual home ranges of male bears (mean [standard deviation]; 504 [312] km2 and 3,886 [4,279] km2, using dBBMM and KDE, respectively) were 3.7–9.4 times larger than that of females (135 [86] km2 and 411 [738] km2, respectively). We found that greater chum salmon (Oncorhynchus keta) consumption was associated with larger annual home ranges for both sexes. In contrast, coastal brown bear populations that consume high levels of salmon often have small annual home ranges. We suggest that the relatively long distance (up to 100 km) between salmon streams and another key resource, denning habitat, is a reason for the positive association between salmon consumption and annual home range size. Although age was not in our top model for annual home range size, younger bears tended to have larger annual home ranges. We documented the fact that individuals of both sexes had the largest annual home ranges of any we could find for brown bears worldwide, using a traditional measure of space use (KDE). However, very large annual home ranges were associated with nonlocalized movements and the alternative method (dBBMM) to delineate these ranges provided more realistic range estimates. We discuss options and limitations of estimating space use and recommend caution when comparing space use between studies. With large-scale industrial infrastructure approved for development in this previously undeveloped region, the size and drivers of bear annual home ranges have numerous management implications. Brown bears with large annual home ranges in northcentral Alaska, where primary productivity is relatively low and denning habitat often far from salmon-bearing streams, are likely to move outside conservation units and encounter more risks as they interact with human infrastructure.

Foxes at your front door? Habitat selection and home range estimation of suburban red foxes (Vulpes vulpes)

The red fox (Vulpes vulpes) is one of the most adaptable carnivorans, thriving in cities across the globe. We used GPS-tracking of five suburban foxes across high-density residential suburbs of Perth, Western Australia to quantify (1) their habitat selection and (2) home range area. All five foxes showed statistically significant avoidance of residential locations (p < 0.001) and preference for parkland (p < 0.001), with native vegetation reserves, golf courses, and water reserves showing disproportionately greater use. Landuse category also influenced their movements, with foxes moving quickest (i.e., commuting) in proximity to roads and slowest (i.e., foraging) when they were further from roads. Three females had core home ranges (50% autocorrelated-corrected kernel density estimate; AKDEc) averaging 37 ± 20 ha or 95% AKDEc averaging 208 ± 196 ha. One male had a 95 ha core home range and 349 ha 95% AKDEc but the other male covered an area ~ 20 times this: using a 371 ha core home range and 7,368 ha 95% AKDEc. The extensive movement patterns we describe are likely to be common for urban foxes, with half of published home range estimates for urban foxes (principally based on VHF data) excluding data for ‘lost’ individuals or animals that showed ‘excursions’. It is likely that the home range estimates for these urban exploiters have therefore been grossly underestimated to date. Further application of GPS trackers that allow remote download will vastly improve our understanding of habitat preference and exploitation of resources by urban foxes.

A stable home: Autocorrelated Kernel Density Estimated home ranges of the critically endangered Elongated tortoise

Home range analysis is a standard and fundamental concept in ecology used to describe animal space use over their lifetimes. Connecting home range sizes with animal characteristics, location, and habitat can be used to inform conservation decisions. Reptiles are frequently lacking robust estimates of space use, particularly reptiles in tropical regions. Here we analyse a publicly available dataset, collected by the authors of this study, describing the movements of Critically Endangered Elongated tortoises Indotestudo elongata. The tortoise data included the locations of 17 tortoises (12 females, 5 males) collected on average once every three days for an average duration of 353.76 SE ± 33.10 days. We use these data to estimate the home range of Elongated tortoise, and explore how tortoise size and sex influences home range size. To mitigate issues resulting from low effective sample sizes and low temporal resolution of the data, we used a modern home range estimation method – Autocorrelated Kernel Density Estimators (AKDE). We found 14 of 17 individuals appear to be occupying a stable home range (using variograms to determine range residency). The average AKDE home range for all 14 individuals with range residency was 44.81 ± 10.44 ha. Bayesian Regression Models suggest comparable size estimates between male and female home ranges, despite males being physically larger than females in both mass and carapace length. These AKDE home range estimates have the added utility of being more comparable with other studies, less susceptible to errors from a suboptimal tracking regime, and are well positioned for inclusion in future meta-analyses. Keywords: testudine, autocorrelated kernel density estimator, spatial ecology, space use, Thailand, Indotestudo elongata

Unique Land Cover Classification to Assess Day-Roost Habitat Selection of Northern Long-Eared Bats on the Coastal Plain of North Carolina, USA

Reproductively successful and over-wintering populations of the endangered northern long-eared bat (Myotis septentrionalis) have recently been discovered on the Coastal Plain of North Carolina. Empirical data on resource selection within the region is limited, likely hindering management of these coastal forests. Our objectives were to determine roosting home range size, selection of day-roost tree species, second- and third-order roosting habitat selection, and to quantify the overall availability of resources in the surrounding landscape. We found core and peripheral roosting home range estimates were large, yet similar to observations from other areas of contiguous forests. Prior to juvenile volancy, female northern long-eared bats appear to select red maple (Acer rubrum), water ash (Fraxinus caroliniana), and loblolly pine (Pinus taeda) as day-roosts, but then use sweetgum (Liquidambar styraciflua), swamp bay (Persea palustris), and water tupelo (Nyssa aquatica) after juvenile volancy. At the second-order spatial scale, roosting home ranges were associated with woody wetlands farther from anthropogenic development and open water. However, within the third-order scale, northern long-eared bats were associated with undeveloped woody wetlands and upland forests, areas containing shorter trees and occurring proximal to open water. Peripheral and core areas were predicted to comprise approximately 20% of the local landscape. Our results show that complex and large tracts of woody wetlands juxtaposed with upland forests in this part of the Coastal Plain may be important for northern long-eared bats locally, results largely consistent with species management efforts in eastern North America.

The Use of Selfie Camera Traps to Estimate Home Range and Movement Patterns of Small Mammals in a Fragmented Landscape.

Simple SummaryCamera trapping allows scientists to study a range of species, across large areas for long periods of time, with little impact on animals. It has been readily used to study movements and territories of large mammals but not for smaller species. This is because they often appear too small on camera to be able to identify distinct individuals. The selfie trap is a method that allows for up close and detailed images of small mammals, and our study aimed to test the ability of the method to track the movement and social behaviour of sugar gliders. We found that the selfie trap is an efficient camera trapping method for estimating home ranges and movements due to its ability to obtain high recapture rates for multiple small mammal species and individuals. In our study landscape, linear strips of habitat were readily utilised by all small mammals, highlighting their importance as wildlife corridors in a fragmented landscape. The use of camera traps to track individual mammals to estimate home range and movement patterns, has not been previously applied to small mammal species. Our aim was to evaluate the use of camera trapping, using the selfie trap method, to record movements of small mammals within and between fragments of habitat. In a fragmented landscape, 164 cameras were set up across four survey areas, with cameras left to record continuously for 28 nights. Live trapping was performed prior to ear mark animals to facilitate individual identification on camera. Four small mammal species (sugar glider; Petaurus breviceps; brown antechinus; Antechinus stuartii, bush rat; Rattus fuscipes, and brown rat; Rattus norvigecus) were recorded on camera (N = 284 individuals). The maximum distance travelled by an individual sugar glider was 14.66 km, antechinus 4.24 km; bush rat 1.90 km and brown rat 1.28 km. Movements of both female and male sugar gliders in linear fragments were recorded at much higher rates than in larger patches of forest sampled in grids. Short term core homes ranges (50% KDE) of 34 sugar gliders ranged from 0.3 ha to 4.2 ha. Sugar glider core home ranges were on average 1.2 ha (±0.17) for females and 2.4 ha (±0.28) for males. The selfie trap is an efficient camera trapping method for estimating home ranges and movements due to its ability to obtain high recapture rates for multiple species and individuals. In our study landscape, linear strips of habitat were readily utilised by all small mammals, highlighting their importance as wildlife corridors in a fragmented landscape.

Application of GPS occurrence data to understand African white-backed vultures Gyps africanus spatial home range overlaps.

Understanding key overlap zones and habitats which are intensively shared by species in space and time is crucial as it provides vital information to inform spatial conservation with maximum benefits. The advent of high‐resolution GPS technologies associated with new analytical algorithms is revolutionizing studies underpinning species spatial and social interaction patterns within ecosystems. Here, using a robust home range estimation algorithm, the autocorrelated kernel density estimator (AKDE) equipped with an equally powerful home range overlap metric, the Bhattacharyya's coefficient (BC), we provide one of the first attempts to estimate and delineate spatial home range overlap zones for critically endangered African white‐backed vultures to inform conservation planning. Six vultures were captured in Hwange National Park using a modified cannon net system after which they were tagged and tracked with high‐resolution GPS backpacks. Overall, results suggested weaker average home range overlaps based on both the pooled data (0.38 ± 0.26), wet non‐breeding seasonal data (0.32 ± 0.23), and dry breeding season data (0.34 ± 0.28). Vultures 4, 5, and 6 consistently revealed higher home range overlaps across all the scales with values ranging between 0.60 and 0.99. Individual vultures showed consistence in space use patterns as suggested by high between‐season home range overlaps, an indication that they may be largely resident within the Hwange ecosystem. Importantly, we also demonstrate that home range overlapping geographic zones are all concentrated within the protected area of Hwange National Park. Our study provides some of the first results on African vulture home range overlaps and segregation patterns in the savanna ecosystem based on unbiased telemetry data and rigorous analytical algorithms. Such knowledge may provide vital insights for prioritizing conservation efforts of key geographic overlap zones to derive maximum conservation benefits especially when targeting wide‐ranging and critically endangered African white‐backed vultures. To this end, spatial overlap zones estimated here, although based on a small sample size, could provide a strong foundation upon which other downstream social and ecological questions can be explored further to expand our understanding on shared space use mechanisms among African vulture species.

Statistical inference for the utilization distribution overlap index (UDOI)

Abstract1. Despite the routine nature of studying home‐range (HR) overlap, a formal inferential framework for overlap analyses has only recently emerged. This framework allows for the computation of approximate confidence intervals (CIs) for the Bhattacharyya coefficient (BC), a pairwise overlap metric with a formal basis in distributional similarity. However, prior comparisons of common overlap metrics suggest that the utilization distribution overlap index (UDOI) is preferred over the BC for analyses of HR overlap in which a measure of space sharing is desired, rather than pure distributional similarity.2. An inferential framework for the UDOI is facilitated by a recent advancement in HR estimation called autocorrelated KDE (AKDE). AKDE explicitly accounts for autocorrelation in tracking data via the fitting of an autocorrelated movement model; uncertainty in fitted model parameters is then leveraged to obtain the uncertainty for estimates of both HR area and overlap. The UDOI is the product of two components: the average probability of encounter (APE) and the area of overlap, A1,2. Thus, we expand the existing inferential framework for the BC to include an estimator and CIs for the UDOI via developing estimators and CIs for its two components. In particular, AKDE error propagation is used to obtain CIs on the APE, while a geometric estimator is employed for estimating A1,2and its uncertainty.3. We use simulated data exhibiting varying degrees of overlap to demonstrate that our estimators provide accurate estimates of true overlap values and our CIs provide reasonable coverage. Furthermore, an empirical case study is presented to illustrate the differential purposes of the BC and UDOI, highlighting the importance of choosing an overlap metric based on the analysis objective.4. By expanding the existing inferential framework for overlap to include the UDOI, we provide ecological researchers with more flexibility to choose an overlap metric that is tailored to their objectives. This allows for more accurate conclusions to be drawn from HR overlap analyses when a measure of space sharing is desired. This method is available in conjunction with the open‐sourceRpackagectmm, using modified overlap functions that are now freely available.

Variable effects of wolves on niche breadth and density of intraguild competitors.

The parallel niche release hypothesis (PNR) indicates that reduced competition with dominant competitors results in greater density and niche breadth of subordinate competitors and which may support an adaptive advantage.We assessed support for the PNR by evaluating relationships between variation in niche breadth and intra‐ and interspecific density (an index of competition) of wolves (Canis lupus) coyotes (C. latrans), and bobcats (Lynx rufus).We estimated population density (wolf track surveys, coyote howl surveys, and bobcat hair snare surveys) and variability in space use (50% core autocorrelated kernel density home range estimators), temporal activity (hourly and overnight speed), and dietary (isotopic δ13C and δ15N) niche breadth of each species across three areas of varying wolf density in the Upper Peninsula of Michigan, USA, 2010–2019.Densities of wolves and coyotes were inversely related, and increased variability in space use, temporal activity, and dietary niche breadth of coyotes was associated with increased coyote density and decreased wolf density supporting the PNR. Variability in space use and temporal activity of wolves and dietary niche breadth of bobcats also increased with increased intraspecific density supporting the PNR.Through demonstrating decreased competition between wolves and coyotes and increased coyote niche breadth and density, our study provides multidimensional support for the PNR. Knowledge of the relationship between niche breadth and population density can inform our understanding of the role of competition in shaping the realized niche of species.

Black bear spatial responses to the Wallow Wildfire in Arizona

AbstractThe Wallow Fire, the largest wildfire in Arizona history, encompassed 2,170 km2 and provided a rare opportunity to examine habitat selection and home ranges of American black bears (Ursus americanus) before and after a wildfire. We had fitted global positioning system (GPS) collars on 47 bears from 2005 to April 2011, and 10 of these were still collared when the fire started in May 2011. We captured and collared an additional 7 black bears within the fire perimeter post‐fire (Jul–Sep 2011 and Jun 2012). To evaluate how black bears were affected by the fire, we fit a step selection function using a conditional mixed effects Poisson regression model to estimate the relative strength of black bear habitat selection in response to burn severity. Additionally, we estimated home range sizes using an autocorrelated kernel density estimator by means of a continuous‐time movement model. We then used a generalized linear model with a negative binomial error distribution and mixed effects to estimate the effect of the burn severity on black bear home range size, while controlling for sex and drought. In spring and summer in years prior to the fire, bears selected areas that later burned in the fire. After the fire, bears used all burn severities, but their selection for high‐severity burns decreased significantly in summer 2011 and fall 2012. Home range sizes were 3.06 times larger pre‐fire than post‐fire. Our study demonstrates that black bears continued to use all burn severities after a major wildfire, and that post‐fire conditions did not result in expanded black bear home ranges.

MAST (Movement Analysis Software for Telemetry data), for the semi-automated removal of false positives from radio telemetry data

IntroductionRadio telemetry, one of the most widely used techniques for tracking wildlife and fisheries populations, has a false-positive problem. Bias from false-positive detections can affect many important derived metrics, such as home range estimation, site occupation, survival, and migration timing. False-positive removal processes have relied upon simple filters and personal opinion. To overcome these shortcomings, we have developed MAST (Movement Analysis Software for Telemetry data) to assist with false-positive identification, removal, and data management for large-scale radio telemetry projects.MethodsMAST uses a naïve Bayes classifier to identify and remove false-positive detections from radio telemetry data. The semi-supervised classifier uses spurious detections from unknown tags and study tags as training data. We tested MAST on four scenarios: wide-band receiver with a single Yagi antenna, wide-band receiver that switched between two Yagi antennas, wide-band receiver with a single dipole antenna, and single-band receiver that switched between five frequencies. MAST has a built in a k-fold cross-validation and assesses model quality with sensitivity, specificity, positive and negative predictive value, false-positive rate, and precision-recall area under the curve. MAST also assesses concordance with a traditional consecutive detection filter using Cohen’s κ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\kappa$$\\end{document}.ResultsOverall MAST performed equally well in all scenarios and was able to discriminate between known false-positive detections and valid study tag detections with low false-positive rates (< 0.001) as determined through cross-validation, even as receivers switched between antennas and frequencies. MAST classified between 94 and 99% of study tag detections as valid.ConclusionAs part of a robust data management plan, MAST is able to discriminate between detections from study tags and known false positives. MAST works with multiple manufacturers and accounts for receivers that switch between antennas and frequencies. MAST provides the framework for transparent, objective, and repeatable telemetry projects for wildlife conservation surveys, and increases the efficiency of data processing.

PIT POP! Bursting the bubble on home-range bias with fine-scale PIT telemetry

Context Improved tracking technologies increase understanding of fish movement, but care is required when comparing studies of different design. Aims We used an approach that allowed fine-scale tracking to compare results from individual-tracking designs to simulated batch-marking designs. Methods Adult Galaxias tantangara (a small freshwater fish) individuals were tagged with 9-mm PIT tags in a small headwater stream and tracked with an accuracy of 1 lineal metre. To evaluate differences between common study designs, data were re-analysed to simulate both batch-marking section size and tracking resolution between 1 and 250 m. Key results Home-range estimates decreased with a smaller section size and tracking resolution. Batch-marking simulations differed in 99% of cases, whereas individual tracking simulations differed in only 17% of comparisons. Comparisons between different methods were rarely statistically equivalent, being so only when section size or resolution was less than 4 m. Implications Importantly, batch-marking studies are often likely to overestimate home-range size, and results from different studies may be comparable only when resolution is very fine or identical, even if the same method was used.

Simulation of the Movement Behavior of Leopardus Guigna using Random Walkers

Scarcity of information regarding the natural history of Leopardus guigna, an endangered felid native to Chile and western Argentina, hampers the successful implementation of conservation strategies. Very little is known about the movement behavior of L. guigna and home range estimates rest on less than a handful of radiotracking studies. Due to the difficulties inherent in any study requiring the live capture of protected species, we suggest a mathematical approach to the modeling of territories occupied by individual guignas. Our approach is based on the hypothesis that L. guigna maintains a sedentary behavior in a specific area of a given territory, whereby starting points can be derived from point observations. In this context, the present article shows a way to simulate a distribution of points in a territory using random walkers to emulate field data as could be obtained by means of telemetry. Our model allows for an estimation of mean distances covered by individual cats from a fixed starting point and thus enables the prediction of interactions with known threats to the species, such as motor vehicles, free-roaming dogs, and people. The knowledge gained in this process can be of much help when defining the boundaries of protected areas and, more generally, in the planning of infrastructure, rural and urban development.

Autocorrelation‐informed home range estimation: A review and practical guide

AbstractModern tracking devices allow for the collection of high‐volume animal tracking data at improved sampling rates over very‐high‐frequency radiotelemetry. Home range estimation is a key output from these tracking datasets, but the inherent properties of animal movement can lead traditional statistical methods to under‐ or overestimate home range areas.The autocorrelated kernel density estimation (AKDE) family of estimators was designed to be statistically efficient while explicitly dealing with the complexities of modern movement data: autocorrelation, small sample sizes and missing or irregularly sampled data. Although each of these estimators has been described in separate technical papers, here we review how these estimators work and provide a user‐friendly guide on how they may be combined to reduce multiple biases simultaneously.We describe the magnitude of the improvements offered by these estimators and their impact on home range area estimates, using both empirical case studies and simulations, contrasting their computational costs.Finally, we provide guidelines for researchers to choose among alternative estimators and anRscript to facilitate the application and interpretation of AKDE home range estimates.

Spatial Ecology of Invasive Predatory Species Informs Predator Control Program for the Jamaican Rock Iguana (Cyclura collei)

Extinctions and population decline of species on islands are often attributed to invasive alien species (IAS). Predation from IAS, such as the Small Indian Mongoose (Urva auropunctata) drove the Critically Endangered Jamaican Rock Iguana (Cyclura collei) to near extinction. Historical and ongoing conservation efforts have restored the population to 500 to 600 adults today. Despite intensive control, IAS incursions into the core area remain common, preventing natural population recruitment. To improve our management and understanding of IAS, we investigated IAS spatial use within the range of the Jamaican Rock Iguana. Seventeen mongooses and cats were tracked with Very High Frequency (VHF) and Global Positioning System (GPS) transmitters for up to 72 days. Several spatial analyses were performed for all IAS, and home ranges were calculated for 13 individuals. Average 100% Minimum Convex Polygon (MCP) home range for VHF tracked mongoose and cats were 25.7 ha and 23.9 ha, respectively. Average 100% MCP, 95% Kernel Density Estimate (KDE), and 50% KDE home range estimates for GPS tracked cats were 78.2 ha, 80.3 ha, and 21.6 ha, respectively. Average IAS range length (distance between the two farthest points) was 979.2 m. Tracking tunnels were also utilized and revealed nearly equal numbers of mongoose tracks inside and outside the iguana core zone. Our results suggest the use of 100 m grid spacing for traps and the introduction of a buffer zone surrounding the core protected zone to restrict IAS incursions. The suggested modifications are expected to mitigate the effects of IAS on the Jamaican Rock Iguana population, improve hatchling survival, and facilitating natural population recruitment and growth.

Fishing for Feral Cats in a Naturally Fragmented Rocky Landscape Using Movement Data

Feral cats are one of the most damaging predators on Earth. They can be found throughout most of Australia’s mainland and many of its larger islands, where they are adaptable predators responsible for the decline and extinction of many species of native fauna. Managing feral cat populations to mitigate their impacts is a conservation priority. Control strategies can be better informed by knowledge of the locations that cats frequent the most. However, this information is rarely captured at the population level and therefore requires modelling based on observations of a sample of individuals. Here, we use movement data from collared feral cats to estimate home range sizes by gender and create species distribution models in the Pilbara bioregion of Western Australia. Home ranges were estimated using dynamic Brownian bridge movement models and split into 50% and 95% utilisation distribution contours. Species distribution models used points intersecting with the 50% utilisation contours and thinned by spacing points 500 m apart to remove sampling bias. Male cat home ranges were between 5 km2 (50% utilisation) and 34 km2 (95% utilisation), which were approximately twice the size of the female cats studied (2–17 km2). Species distribution modelling revealed a preference for low-lying riparian habitats with highly productive vegetation cover and a tendency to avoid newly burnt areas and topographically complex, rocky landscapes. Conservation management can benefit by targeting control effort in preferential habitat.

Sport fish home range responses to a littoral coarse woody habitat addition in a north‐temperate lake

AbstractBehavioural responses of fishes to littoral zone habitat enhancements are relatively understudied in diverse fish communities but are critical for understanding overall fish community responses. To advance knowledge on effects of coarse woody habitat (CWH) littoral zone enhancements, we initiated a long‐term study on Sanford Lake, Vilas County, Wisconsin, where 160 trees were added to the littoral zone of the lake in 2018. We tested for short‐term home range responses in muskellunge (Esox masquinongy), smallmouth bass (Micropterus dolomieu) and walleye (Sander vitreus) to this CWH addition. We used radio telemetry data collected premanipulation (2017) and postmanipulation (2018 and 2019) to construct annual home range estimates for each species. Limited kernel density (LKD) estimates, which partially exclude terrestrial areas, were used for estimating 50% and 95% home ranges. Over the course of the three years, average home ranges for each study species increased suggesting a behavioural response to the CWH addition. Muskellunge had the greatest home range estimate increase, followed by smallmouth bass and then walleye. Muskellunge and smallmouth bass had similar home ranges, which were larger than walleye home ranges. Increased home ranges across species could be a searching or deviation from premanipulation equilibrium home range response as a result of the CWH serving as a prey fish refuge, which may make them relatively inaccessible to predators. Our results suggest that fish behavioural responses to CWH additions may be species‐specific and should be taken into consideration prior to implementing littoral habitat enhancements in diverse fish communities.

Seasonal variation in home range size of evening bats (Nycticeius humeralis) in an urban environment

Abstract Despite the negative impacts of urbanization on bats, green spaces in urban environments, such as parks, cemeteries, and golf courses, have the potential to provide resources necessary for these animals. Water resources in these areas include natural or semi-natural ponds, streams, and drainage ditches. Such water resources, however, are frequently ephemeral when subject to prolonged periods of high temperatures and low precipitation. We hypothesized that home ranges of evening bats (Nycticeius humeralis) would increase in size or shift from urban green spaces into surrounding neighborhoods to access alternative resources, such as residential swimming pools, when water resources in green spaces are scarce. To explore whether seasonal variations in bat home ranges occurred, we radio-tracked resident evening bats in a local park system during their summer activity period 2017–2019 in Fort Worth, Texas, USA. We used Local Convex Hulls created by associating point locations with their nearest neighbor to estimate home range size, location, and the percentage area that fell within the surrounding neighborhood. We compared these variables to temperature and precipitation using various regression models. We successfully tracked 30 bats over the 3-year period and found a positive correlation between home range size and temperature. Home range sizes increased 6-fold when temperatures exceeded 30°C. Our study indicates the importance of urban neighborhoods surrounding green spaces in providing alternative resources, such as water, for bats. If managed appropriately, these urban areas have the potential to act as oases for bat populations.

Measuring the Degree of Overlap and Segregation among Multiple Probabilistic Home Ranges: A New Index with Illustrative Application to the Lesser Kestrel Falco naumanni.

Simple SummaryIntraspecific and interspecific interactions regulate the extent and spatial patterns of animal home ranges. If we are able to estimate the home range overlap for a large number of individuals, populations and/or species, then we can readily identify important ecological properties, such as social network structure, competition during the breeding season, contact rates with implications for disease transmission, change in space use over time, interactions among different age classes and site fidelity for a particular individual, population or species. We can also evaluate the robustness of probabilistic home range assessment through the degree of overlap of several estimators. Accordingly, in this study, we first solve the issue of measuring the degree of overlap/segregation among a large number of probabilistic animal home ranges and provide a demonstrative case study.Home range overlap/segregation has several important applications to wildlife conservation and management. In this work, we first address the issue of measuring the degree of overlap/segregation among an arbitrarily large number (i.e., n ≥ 2) of probabilistic animal home ranges (i.e., utilization distributions). This subject matter has recently been solved for home ranges measured as polygons (e.g., percent minimum convex polygons and multinuclear cores) but not yet for probabilistic ones. Accordingly, we introduce a novel index named the PGOI (probabilistic general overlap index), and its complement, the PGSI (probabilistic general segregation index), an index for computation of probabilistic home range overlap/segregation at individual, population and species levels. Whatever the number of probabilistic home ranges, the PGOI returns a single score ranging in the [0, 100] interval. We applied the PGOI to five lesser kestrels (Falco naumanni) at Santeramo in Colle (Apulia region; Southern Italy) as a case study. Our new index can be applied to any animal species and to home ranges derived from any type of probabilistic home range estimator.

Big Cats in the Big City: Spatial Ecology of Mountain Lions in Greater Los Angeles

ABSTRACTLarge carnivores can represent the ultimate challenge for conservation in developed landscapes because of their large area requirements and potential for conflict with humans. Some large carnivores such as mountain lions (Puma concolor) can use a wide range of biomes and vegetation types, and in southern California, USA, they persist in metropolitan Los Angeles, a megacity of 18 million people. Understanding how large carnivores use highly altered landscapes is important for their conservation and management. We estimated home range size, landscape use, and landscape selection for mountain lions in the Santa Monica Mountains and surrounding areas for 29 subadult and adult animals from 2002 to 2016, using 128,133 locations from global positioning system (GPS)‐collars. Home range size was similar to that reported by other researchers; home ranges averaged 372 km2 for adult males and 134 km2 for adult females, except for 2 adult males in isolated habitat fragments that maintained 2 of the smallest adult male home ranges ever recorded (24 km2 and 54 km2). Mountain lions very rarely entered developed areas, consistently avoided altered open areas such as golf courses, cemeteries, or other landscaped spaces, and showed a positive relationship between home range size and amount of development, all indicating that developed areas have reduced value for mountain lions. Mountain lions from all sex and age classes selected areas closer to development than expected by chance, which could be related to the presence of mule deer (Odocoileus hemionus) or other prey in or adjacent to urbanization. For 2 adult males that occupied home ranges within the most urban portions of our study area, their response to urban development differed strongly across diurnal periods, ranging from avoidance during the day to selection at night. Shrub vegetation types, especially chaparral, were important in terms of habitat use and resource selection, highlighting their importance for conservation of the species in southern California. North America's largest felid can thrive in shrublands and persist even in one of the world's largest cities, although they only very rarely venture into developed areas within that city. © 2021 The Wildlife Society.

Spatial analysis of rehabilitated American black bears to assess conflict potential

Analyses of postrelease movements and behaviors may indicate the propensity of rehabilitated American black bears (Ursus americanus) to be involved in human–bear conflicts. We assessed various linear and Euclidean distances and constructed collar duration and seasonal home-range estimates using Dynamic Brownian Bridge Movement Models to determine whether 28 rehabilitated yearling bears released in North Carolina, USA, between 2015 and 2018 established a home range or remained transient. Male bears typically moved farther than females, and Mountain region bears typically moved farther than Coastal Plain region bears. All bears showed equally tortuous movement patterns across regions and sexes. Seven bears traveled greater distances than the average of all bears in this study and 2 bears did not establish a home range; these results indicate transient behavior. No bears exhibiting transient behavior were involved with human–bear conflicts, but the North Carolina Wildlife Resources Commission received calls concerning 4 resident bears, 2 of which exhibited behaviors that would potentially lead to human–bear conflicts. Knowledge of postrelease bear movements will inform management decisions by improving understanding of how movements may affect human–bear interactions.