Estimated Home Range Size Research Articles

Marine Fish Movement: home range sizes for commercially relevant species

Estimates of home range sizes for marine fishes are essential for designing and assessing the effects of spatial wildlife conservation policies and management interventions. However, in situ studies of marine species movement are challenging and often expensive, resulting in a paucity of data on the home range size of the vast majority of marine fishes. Here, we develop a set of new datasets, which we have collectively named Marine Fish Movement, that synthesises published empirically evaluated home ranges reported for adult marine fishes that interact with fisheries and leverage these data to estimate home range sizes for unstudied species. The empirical data contain estimated home range sizes (km2) for 193 species across 63 family groups from 179 studies published between 1971 and 2022. We use a random forest regression model to estimate home range sizes (km2) for 664 fished marine species currently lacking home range estimates. Marine Fish Movement can inform spatial interventions including the design and management of marine protected areas and dynamic fisheries management to meet sustainability goals.

Population status of the range-restricted Red Lark Calendulauda burra in a conservation area stronghold

Many desert birds are vulnerable to anthropogenic global warming and landscape transformation, particularly in the case of range-restricted species. We quantified suitable habitat and the current population of Red Larks Calendulauda burra (family Alaudidae), a range-restricted southern African species, in a conservation area thought to be one of the species’ strongholds — the Black Mountain Mine Conservation Area (BMMCA) in the Northern Cape, South Africa. We modelled habitat suitability and estimated home range sizes using telemetry data and kernel density estimates. Home range sizes did not differ between males (42.4 ± 28.3 ha; n = 5) and females (41.9 ± 31.3 ha; n = 5). Transect data and home range density models indicated densities of 0.086–0.127 individuals·ha-1 for adults in suitable habitat. An estimated 33.2% (30.2 km2) of the BMMCA is suitable habitat for Red Larks, suggesting a population of 232–382 individuals. This population estimate is equivalent to <50% of the population estimated for the BMMCA in 1989. Our findings here, combined with a recent analysis showing that much of the species’ range will become thermally unsuitable for its persistence by the end of the 21st century, suggest that urgent conservation action is needed to ensure the Red Lark’s future in coming decades.

Female black bear home range and resource selection in relation to West Virginia mine lands

AbstractWildlife space use is a key component to consider when determining effective conservation and management practices. Home range size and resource selection can vary temporally and spatially depending on mortality risks in the area and access to food resources. Lands used for coal mining can contain unique mortality risks and food resources for American black bears (Ursus americanus) relative to surrounding landscapes due to hunting restrictions, vegetation planted as part of the reclamation process, and other anthropogenic food resources. We examined the influence of mining sites on resource selection of female black bears in southern West Virginia, USA, during 2007 and 2008. We estimated home range size with Brownian Bridge movement models and evaluated variation in home range size with mixed‐effects linear regression. We evaluated resource selection with mixed‐effects Poisson point process models. On mine sites, the mean 95% home range for female black bears was 1,996 ha (SD = 2,633) in the autumn and 544 ha (SD = 238) in the spring, and on non‐mine sites the mean 95% home range was 1,926 ha (SD = 1,292) in the autumn and 771 ha (SD = 480) in the spring. Our resource selection model indicated black bears used nonhunting zones associated with mine lands much greater than their availability, and that black bears in mine areas disproportionately used areas in close proximity to anthropogenic structures. Interannual variation in home range size was likely associated with mast conditions, because smaller home ranges were associated with high mast production. Our data suggest black bears may be using non‐hunting zones within mine lands as refugia from hunting and are using anthropogenic food sources available at refuse sites on mine lands, which may increase regional black bear populations in areas with high mining activity.

Quantifying seasonal variations in space use within the home range of Burbot

AbstractObjectiveAdvances in acoustic telemetry have assisted biologists in understanding migration patterns, space use, survival, and the effects of human influences on aquatic species. Using fine‐scale positioning, fisheries managers can quantify home range size fluctuations throughout the year and even identify spawning areas. Burbot Lota lota population dynamics have been studied across their range, while movement dynamics have been briefly investigated. Our objective was to assess seasonal variations of Burbot space use using estimations of home range size with an attempt to infer spawn timing.MethodsThirty‐two acoustic‐tagged Burbot were used to study home range size in Bad Medicine Lake, Minnesota, from April 2019 to June 2020.ResultFemale estimated home range size was significantly larger than that of males. Estimated home range size increased following ice formation in December and continued through March. Average home range estimates were largest in the middle of March and smallest in April, assumed to be caused by spawning and postspawn behaviors, respectively.ConclusionThe results suggest that Burbot movement increased during the winter months, which may cause potential increases in vulnerability during spawning. High exploitation rates are possible in situations where spawning and feeding Burbot encounter elevated angling pressure. Future research should continue to assess the movement dynamics and potential site fidelity of Burbot populations by monitoring spawning grounds and if the same areas are used year after year. The results of this study improve the knowledge of areas used by Burbot in lakes, which can assist with management of Burbot in Bad Medicine Lake. Furthermore, we highlighted how Burbot movement increased during spawn timing, which could contribute to increased encounters with anglers.

Environmental drivers of global variation in home range size of terrestrial and marine mammals.

As animal home range size (HRS) provides valuable information for species conservation, it is important to understand the driving factors of HRS variation. It is widely known that differences in species traits (e.g. body mass) are major contributors to variation in mammal HRS. However, most studies examining how environmental variation explains mammal HRS variation have been limited to a few species, or only included a single (mean) HRS estimate for the majority of species, neglecting intraspecific HRS variation. Additionally, most studies examining environmental drivers of HRS variation included only terrestrial species, neglecting marine species. Using a novel dataset of 2800 HRS estimates from 586 terrestrial and 27 marine mammal species, we quantified the relationships between HRS and environmental variables, accounting for species traits. Our results indicate that terrestrial mammal HRS was on average 5.3 times larger in areas with low human disturbance (human footprint index [HFI] = 0), compared to areas with maximum human disturbance (HFI = 50). Similarly, HRS was on average 5.4 times larger in areas with low annual mean productivity (NDVI = 0), compared to areas with high productivity (NDVI = 1). In addition, HRS increased by a factor of 1.9 on average from low to high seasonality in productivity (standard deviation (SD) of monthly NDVI from 0 to 0.36). Of these environmental variables, human disturbance and annual mean productivity explained a larger proportion of HRS variance than seasonality in productivity. Marine mammal HRS decreased, on average, by a factor of 3.7 per 10°C decline in annual mean sea surface temperature (SST), and increased by a factor of 1.5 per 1°C increase in SST seasonality (SD of monthly values). Annual mean SST explained more variance in HRS than SST seasonality. Due to the small sample size, caution should be taken when interpreting the marine mammal results. Our results indicate that environmental variation is relevant for HRS and that future environmental changes might alter the HRS of individuals, with potential consequences for ecosystem functioning and the effectiveness of conservation actions.

Fragmented forest affects the southern black-horned capuchin (Sapajus nigritus cucullatus) in the Argentinean Atlantic Forest.

The southern black-horned capuchin, Sapajus nigritus cucullatus, is considered Near Threatened on the IUCN Red List and Vulnerable in Argentina. The species is mainly threatened by habitat loss and fragmentation. The aim of this study was to compare range size, group size, and density in S. n. cucullatus groups between areas of continuous and fragmented habitat in the Atlantic Forest in Argentina. The study was carried out in two areas in northern Misiones province, one continuous and one anthropogenic fragment. Fieldwork was carried out for 5 days each month from November 2019 to March 2020 and from November 2020 to March 2021. SARS-CoV-2 restrictions meant we could not survey in the intervening period. Group counts were made on existing trails and subsequent group follows. We georeferenced encounters and follows to estimate home range sizes. We calculated density based on home range modeling using 100% minimum convex polygons (MCP), and compared these using generalized linear models (GLM). Smaller groups and lower density of S. n. cucullatus were found in continuous forest, with group sizes between 12 and 23 individuals, and density of 0.14 ind/ha, whereas in the fragmented forest, group sizes were between 32 and 36, with density of 0.62 ind/ha (n = 107; zero-inflated negative binomial regression [ZINB], p < 0.05). The higher density in forest fragments may be due to reduced dispersal ability. This work highlights data on species plasticity that could contribute to the development of conservation management strategies for S. n. cucullatus and its habitat.

How does an urban landscape influence spatiotemporal ecology of South American coatis (Nasua nasua)?

Abstract Increasing urbanization and consequent habitat fragmentation and loss call for studies of the influence of urbanization on native fauna. South American Coati (Procyonidae: Nasua nasua) live in groups and are common in urban areas of South America. Here, we aimed to understand how coatis occupy and select space, and whether they change their circadian activity in an urban environment. We estimated home range sizes, verified any overlap, and evaluated the effects of sex and weight on home range size. We also described coati activity patterns associated with habitat selection. Animals established their home ranges only within the study area, with few exploratory exits to surrounding areas. Furthermore, our home range estimates of 0.66 km2 are lower than previously found in natural habitats. We did not observe an effect of sex or weight on home range size. Coatis predominantly selected forested areas and explored houses only early in the morning. We suggest that this demonstrates the need for forested areas for survival of the species. Regarding activity patterns, coatis were active only during the day, as described for the species in its natural environment. Human barriers—in addition to human refuse that serves as food—could reduce the home range sizes. Our data demonstrate differences in home range size, but not circadian activity or habitat selection when compared to coatis in their natural environment.

Trade-Off between Sampling Frequency and Duration and Their Influences on the Estimation of Space Use of Japanese Macaques

Space use, estimated based on location data, provides fundamental knowledge in the basic and applied ecology of wild animals. There is a trade-off between sampling frequency and duration in location data which are collected from a tracking device attached to an animal because the battery of the device has a limited life. In this study, we assessed how different combinations of sampling frequency and duration would affect estimates for home-range size and maximum utilization area (MUA) of Japanese macaques, using datasets subsampled by reducing frequency and/or duration from the original dataset. Estimates of MUA were likely to be overestimated if the sampling duration was shorter than 80 days for Japanese macaques. Reductions in sampling frequency and duration had opposite effects on estimates of home-range size: the estimated area decreased with decreasing sampling duration, while it increased with decreasing sampling frequency. Moreover, these opposite effects can be offset when the sampling frequency and duration are simultaneously reduced. We discussed the applicability of our results to animals other than Japanese macaques and how to design the sampling frequency and duration in future research.

A case report assessing the utility of a low-cost tracking GPS device for monitoring terrestrial mammal movements

BackgroundAccurate data on animal movements can highlight behavioural and ecological issues, such as territorial interactions, barriers to migration patterns, including compromised movement corridors, or avoidance of deteriorating habitats, and disease transmission, thus helping in conservation decision making. This study examines the utility of mOOvement global positioning system (GPS) tags, a low-cost cattle ear tag tracking device to monitor movements of terrestrial mammal populations in South Australia.ResultsStationary tags (n = 40) were used to test horizontal accuracy with a median location error of 33.26 m (IQR = 16.9–59.4), and maximum recorded error of 410 m. The locational accuracy was weakly influenced by the horizontal dilution of precision (HDOP), a measure of satellite availability and geometry, and overhead canopy cover. Numerous tags produced infrequent and inconsistent readings, median of 12 records per day (IQR = 6–12), correlating negatively with the tag’s distance from the centrally located LoRa antenna; however, some tags recorded fewer than one position per day.ConclusionsWe propose that the primary cause of mOOvement tag inadequacy is the use of only the GPS satellite constellation (USA, 1978), which does not provide adequate coverage in either satellite number or geometry in the sky at the − 35° latitude to calculate accurate positions regularly over 24 h, unlike the multiple constellations available in the global navigation satellite system (GNSS). We conclude that GPS tags are unsuitable for studies requiring high locational accuracy or identification of an individual’s social interactions, where the GPS constellation has a limited number of satellites available during prolonged periods. They can, however, be used to provide estimates of home range size or track large scale daily movements of animals in more equatorially located regions.

Habitat selection and water dependency of feral burros in the Mojave Desert, California, USA

AbstractExpansion of feral burro (Equus asinus) populations across the southwestern United States is causing human–wildlife conflicts including rangeland degradation, competition with livestock and native species, and burro–vehicle collisions. On the Fort Irwin National Training Center (NTC) in California, feral burros interfere with military training and are involved in vehicle collisions and other conflicts (e.g., burros blocking access to buildings). Limited data on burro movements and resource use poses a challenge for the development of management plans and mitigation strategies. We estimated home range size, second‐ and third‐order seasonal resource selection, and water dependency of 10 adult female feral burros fitted with global positioning system (GPS) collars on the NTC from November 2015 to April 2017. Mean 95% autocorrelated kernel home range size of female burros (253.9 ± 30.7 km2 [SE]) did not differ among seasons or between burros that resided close to or far from urban areas. Burros selected areas closer to water in all seasons and at both spatial scales, but selection was stronger in the dry season and at the landscape scale. When available, burros strongly selected for areas closer to urban areas. Burros consistently selected for areas with green forage and at lower elevations, but selection for other topographical features was variable. Water use patterns were consistent with the resource selection results. Burros visited water sources twice as often (every 22.2 ± 6.3 hr) during the hot‐dry season (Apr–Oct) compared to the cool‐wet seasons (Nov–Mar; 2015: 45.9 ± 21.0; 2016: 39.7 ± 9.3 hr). Our results suggest that urban areas, and resources therein, and water sources have the biggest influence on burro resource selection, and management plans could focus mitigation programs on these areas.

Satellite telemetry reveals habitat selection decisions by black oystercatchers across seasonal, diel, and tidal cycles.

Habitat use of indicator species is used to prioritize management activities. However, habitat use can vary temporally in response to changes in predation risk and foraging rewards. We deployed satellite tags on 20 black oystercatchers (Haematopus bachmani) in four regions of British Columbia, Canada, to examine habitat use and selection decisions across seasonal, diel and tidal cycles. We characterized the shoreline in each region and used GLMMs to investigate how habitat characteristics influenced shoreline use by tracked birds. For individuals, we estimated home range size and the frequency key features of the shoreline were re-visited. Black oystercatchers generally made greater-than-expected use of rocky islets and shoreline with freshwater outflows, less tree cover and greater intertidal area. However, while black oystercatchers preferred islets and shoreline with less tree cover at most/all time periods, they only exhibited preferences for greater intertidal area during low tides, and preferences for shoreline with freshwater outflows during the nonbreeding season, day, and high tides. Individual home ranges, on average, contained 46 km of shoreline (range: 12-156 km) and individuals used 10.4 km (range: 6.7-13.9 km). Individuals made greater use of larger islets with less tree cover that were closer to outflows, and greater use of outflows associated with larger streams, greater intertidal areas and gravel substrates. Black oystercatchers' habitat preferences likely reduce predation risk (rocky islets and shoreline with less tree cover) and increase foraging rewards (shoreline with freshwater outflows, greater intertidal area, and gravel substrates). However, habitat preferences appear sensitive to constraints on movement in the breeding season and changes in foraging rewards across the diel and tidal cycle, highlighting the importance of examining habitat use at multiple temporal scales. Black oystercatchers are considered indicators of rocky intertidal health; therefore, critical habitat is expected to be important for a suite of wildlife dependent on safe and productive coastline.

Golden-bellied mangabeys (Cercocebus chrysogaster) exhibit a larger home range and longer travel distances than those of bonobos (Pan paniscus) at LuiKotale, Democratic Republic of the Congo.

Primate ranging behavior is associated with numerous social and ecological correlates. Interspecific comparisons of ranging behavior can therefore provide insight into the socio-ecological conditions that characterize a species' niche within its community. We provide the first description of ranging behavior in golden-bellied mangabeys (Cercocebus chrysogaster), using sympatric bonobos (Pan paniscus) as a comparison. Over 6 months, we recorded GPS tracks at 1- and 5-min intervals from one habituated golden-bellied mangabey group and two habituated bonobo communities at LuiKotale, central Democratic Republic of the Congo. We compared estimates of home range size, time spent at different elevations, and hourly travel distances between species. We modeled daily travel distances against total monthly rainfall to investigate seasonal variation in daily ranging. The golden-bellied mangabey home range was similarly sized or larger than each of the two bonobo communities at LuiKotale across estimation methods. Mangabeys visited more of their range per day and spent more time in terra firma forest and less time in swamps than bonobos. Mangabeys traveled significantly farther per day and during midday hours than bonobos, but travel distances did not relate to monthly rainfall in either species. Golden-bellied mangabeys exhibited wide daily ranging behavior that more closely resembled that of sympatric bonobos than other Cercocebus species. Large homes ranges in mangabeys are likely influenced by food availability in terra firma forest, especially as groups appear to travel long distances between fruit trees and terrestrial food patches. Maximizing daytime activity may help mangabeys avoid competition from heterospecifics and indicates temporal niche partitioning in this primate community.

Spatial patterns of large African cats: a large‐scale study on density, home range size, and home range overlap of lions Panthera leo and leopards Panthera pardus

Abstract Spatial patterns of and competition for resources by territorial carnivores are typically explained by two hypotheses: 1) the territorial defence hypothesis and 2) the searching efficiency hypothesis. According to the territorial defence hypothesis, when food resources are abundant, carnivore densities will be high and home ranges small. In addition, carnivores can maximise their necessary energy intake with minimal territorial defence. At medium resource levels, larger ranges will be needed, and it will become more economically beneficial to defend resources against a lower density of competitors. At low resource levels, carnivore densities will be low and home ranges large, but resources will be too scarce to make it beneficial to defend such large territories. Thus, home range overlap will be minimal at intermediate carnivore densities. According to the searching efficiency hypothesis, there is a cost to knowing a home range. Larger areas are harder to learn and easier to forget, so carnivores constantly need to keep their cognitive map updated by regularly revisiting parts of their home ranges. Consequently, when resources are scarce, carnivores require larger home ranges to acquire sufficient food. These larger home ranges lead to more overlap among individuals' ranges, so that overlap in home ranges is largest when food availability is the lowest. Since conspecific density is low when food availability is low, this hypothesis predicts that overlap is largest when densities are the lowest. We measured home range overlap and used a novel method to compare intraspecific home range overlaps for lions Panthera leo (n = 149) and leopards Panthera pardus (n = 111) in Africa. We estimated home range sizes from telemetry location data and gathered carnivore density data from the literature. Our results did not support the territorial defence hypothesis for either species. Lion prides increased their home range overlap at conspecific lower densities whereas leopards did not. Lion pride changes in overlap were primarily due to increases in group size at lower densities. By contrast, the unique dispersal strategies of leopards led to reduced overlap at lower densities. However, when human‐caused mortality was higher, leopards increased their home range overlap. Although lions and leopards are territorial, their territorial behaviour was less important than the acquisition of food in determining their space use. Such information is crucial for the future conservation of these two iconic African carnivores.

Movement predictability of individual barn owls facilitates estimation of home range size and survival

BackgroundThere is growing attention to individuality in movement, its causes and consequences. Similarly to other well-established personality traits (e.g., boldness or sociability), conspecifics also differ repeatedly in their spatial behaviors, forming behavioral types (“spatial-BTs”). These spatial-BTs are typically described as the difference in the mean-level among individuals, and the intra-individual variation (IIV, i.e., predictability) is only rarely considered. Furthermore, the factors determining predictability or its ecological consequences for broader space-use patterns are largely unknown, in part because predictability was mostly tested in captivity (e.g., with repeated boldness assays). Here we test if (i) individuals differ in their movement and specifically in their predictability. We then investigate (ii) the consequences of this variation for home-range size and survival estimates, and (iii) the factors that affect individual predictability.MethodsWe tracked 92 barn owls (Tyto alba) with an ATLAS system and monitored their survival. From these high-resolution (every few seconds) and extensive trajectories (115.2 ± 112.1 nights; X̅ ± SD) we calculated movement and space-use indices (e.g., max-displacement and home-range size, respectively). We then used double-hierarchical and generalized linear mix-models to assess spatial-BTs, individual predictability in nightly max-displacement, and its consistency across time. Finally, we explored if predictability levels were associated with home-range size and survival, as well as the seasonal, geographical, and demographic factors affecting it (e.g., age, sex, and owls’ density).ResultsOur dataset (with 74 individuals after filtering) revealed clear patterns of individualism in owls’ movement. Individuals differed consistently both in their mean movement (e.g., max-displacement) and their IIV around it (i.e., predictability). More predictable individuals had smaller home-ranges and lower survival rates, on top and beyond the expected effects of their spatial-BT (max-displacement), sex, age and ecological environments. Juveniles were less predictable than adults, but the sexes did not differ in their predictability.ConclusionThese results demonstrate that individual predictability may act as an overlooked axis of spatial-BT with potential implications for relevant ecological processes at the population level and individual fitness. Considering how individuals differ in their IIV of movement beyond the mean-effect can facilitate understanding the intraspecific diversity, predicting their responses to changing ecological conditions and their population management.

Movement and ranging behaviour of long-nosed potoroos (Potorous tridactylus) in south-west Victoria, Australia

Context A comprehensive understanding of movements and space use can underpin the effective management of threatened species. GPS dataloggers can collect large amounts of high-quality movement data, and recent advances in statistical approaches allow for robust estimates of home range size to be generated. Until recently, technological and practical constraints have generally restricted the collection of movement data via GPS dataloggers to larger species. However, reductions in the size and weight of GPS dataloggers now allow for this technology to be applied to smaller species. Aims The aim of this study was to describe the home range and movement patterns of a nationally vulnerable, native Australian ground-dwelling mammal, the long-nosed potoroo (Potorous tridactylus), in south-west Victoria, mainland Australia. Methods We attached GPS dataloggers to 40 long-nosed potoroos between 2020 and 2022 and estimated home range size using dynamic Brownian Bridge movement models. We evaluated the influence of physiological factors such as body mass and sex on home range size and described patterns of home range overlap between and within sexes. Key results Mean home range sizes were estimated to be 13.73 ha (95% CI: 10.9–16.6) and 6.67 ha (95% CI: 5.49–7.85) for males and females respectively. Home range size scaled with body mass in males but not females, and ranges were largely overlapping – although there was some evidence of intrasexual spatial partitioning of core range areas in females. Conclusions Ours is the first application of GPS dataloggers to this species, and our home range estimates are over twice as large as other reported estimates for mainland Australia. Long-nosed potoroos may range across larger areas than previously predicted on mainland Australia. Implications This knowledge may be used to optimise the management of long-nosed potoroo populations before and after fire – a key threatening process for this species. Our study highlights the value of integrating GPS dataloggers and robust home range estimators when describing the movement ecology of a population.

Spatial ecology meets eradication of feral cats on Auckland Island

Restoration initiatives of ecosystems transformed by human actions require optimisation of eradication measures of introduced species, particularly in fragile insular ecosystems. We studied aspects of the spatial ecology of introduced feral cats (Felis catus) on subantarctic Auckland Island of New Zealand to assist eradication efforts of pests from this remote, biologically rich island. Firstly, we estimated home range sizes and identified core areas of activity based on movement-rooted dynamic Brownian bridge models.

Home range, habitat use, and activity patterns of African wolves (Canis lupaster) in the Ethiopian highlands

African wolves (Canis lupaster) and Ethiopian wolves (C. simensis) occur often sympatrically across habitats in the Ethiopian Highlands, with recent studies finding evidence for interspecific competition. However, unlike the well-studied Ethiopian wolf, comparatively little is known about the ecology of the African wolf in the Ethiopian Highlands. To address this empirical gap, we collected data on home range size, habitat use, and activity patterns of radio-collared African wolves at the Guassa Menz Community Conservation Area (GCCA) and Borena Saynt Worehimenu National Park (BSNP). We followed the African wolves (5 in GCCA, 6 in BSNP) for 16 months and had 659 ± 83 encounters with each individual. The mean 95% kernel density estimate home range size of African wolves was higher in BSNP (4.5 ± 1.5 km2) than at GCCA (2.2 ± 0.7 km2). In 55% (n = 3934) of the encounters the wolves were found to be solitary, whereas in other encounters we found them in groups of two to seven. At both sites, the African wolves were more often found in areas close to human settlements than in more intact habitat, and they were mainly active at dawn and dusk. These results show flexibility in African wolf socioecology in response to habitat fragmentation and anthropogenic disturbance. We recommend further studies on major causes of spatial and temporal niche partitioning of Ethiopian wolves and African wolves in the Ethiopian Highlands.

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.

Does the punishment fit the crime? Consequences and diagnosis of misspecified detection functions in Bayesian spatial capture-recapture modeling.

Spatial capture–recapture (SCR) analysis is now used routinely to inform wildlife management and conservation decisions. It is therefore imperative that we understand the implications of and can diagnose common SCR model misspecifications, as flawed inferences could propagate to policy and interventions. The detection function of an SCR model describes how an individual's detections are distributed in space. Despite the detection function's central role in SCR, little is known about the robustness of SCR‐derived abundance estimates and home range size estimates to misspecifications. Here, we set out to (a) determine whether abundance estimates are robust to a wider range of misspecifications of the detection function than previously explored, (b) quantify the sensitivity of home range size estimates to the choice of detection function, and (c) evaluate commonly used Bayesian p‐values for detecting misspecifications thereof. We simulated SCR data using different circular detection functions to emulate a wide range of space use patterns. We then fit Bayesian SCR models with three detection functions (half‐normal, exponential, and half‐normal plateau) to each simulated data set. While abundance estimates were very robust, estimates of home range size were sensitive to misspecifications of the detection function. When misspecified, SCR models with the half‐normal plateau and exponential detection functions produced the most and least reliable home range size, respectively. Misspecifications with the strongest impact on parameter estimates were easily detected by Bayesian p‐values. Practitioners using SCR exclusively for density estimation are unlikely to be impacted by misspecifications of the detection function. However, the choice of detection function can have substantial consequences for the reliability of inferences about space use. Although Bayesian p‐values can aid the diagnosis of detection function misspecification under certain conditions, we urge the development of additional custom goodness‐of‐fit diagnostics for Bayesian SCR models to identify a wider range of model misspecifications.

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.