Large Home Range Research Articles

Camera‐trapping density estimates suggest critically low population sizes for the Wet Tropics subspecies of the spotted‐tailed quoll (Dasyurus maculatus gracilis)

AbstractAccurate estimates of distribution and population density are critical for the management of threatened species. This is particularly pertinent for mammalian predators, whose generally low population density, elusive nature, and large home range requirements make it difficult to detect declines. We aimed to refine population estimates of the northern spotted‐tailed quoll (Dasyurus maculatus gracilis) in the Wet Tropics bioregion, to estimate the total number of adults, the likely size of subpopulations across the known distribution of the subspecies, and its associated conservation status. We performed targeted upland camera‐trapping surveys from June 2017 to May 2019. To calculate population densities, we used a combination of the number of individuals identified from each survey and the mean maximum distance moved from three life history stages. We then extrapolated these estimates to modelled suitable habitat areas, refined by the camera‐trapping surveys. Population sizes for the six defined subpopulations were estimated, and ranged from approximately 5 to 105 individuals. The total population was estimated to be 221 individuals. This total population estimate, and the estimates for each of the subpopulations, are lower than previous published estimates and are cause for concern. Given the low population estimates presented here and unresolved threats driving declines in some subpopulations, we suggest elevation of this subspecies to Critically Endangered under the EPBC Act.

Population size, morphometrics and movement patterns of the brush-tailed mulgara (Dasycercus blythi): is predation by mammalian predators having an effect?

Worldwide predation by feral cats has caused severe declines in many animal species. Prior to extinction, threatening processes typically alter species behaviour, habitat use, survival and reproductive rates. By monitoring these parameters, we may be able to determine if feral cats are a significant threatening process to a species prior to extinction. We aimed to test whether feral cats are negatively affecting the population size, morphometrics and movement patterns of mulgaras (Dasycercus blythi) on the Matuwa Indigenous Protected Area, in the arid rangelands of Western Australia. We hypothesised that mulgaras, which inhabit a cat-free environment, would have a larger home range and denser population, and be in better condition than those that inhabited an adjacent area with a suppressed density of feral cats. We trapped (n = 64), and radio-tracked (n = 19) mulgara inside and outside an 1100 ha cat-free fenced enclosure on five occasions in 2012. Treatment (i.e. inside or outside the cat-free enclosure) was a significant variable for explaining variation in mulgara density. There was no significant difference in morphometrics or the home ranges of mulgara between the sexes or treatments. Head length, pes length and weight, as well as tail width and length, were significantly different between sexes and over time, suggesting that seasonal variation influences mulgara populations more than low levels of cat predation.

Home range variability and philopatry in Cinereous vultures (Aegypius monachus) breeding in Iberia

Large scavengers are strongly dependent on environmental conditions and carrion distribution and abundance, so season and breeding-related factors may influence the spatial ecology of species such as the Cinereous Vulture (Aegypius monachus), the largest European raptor. Iberia holds one of the biggest populations worldwide, but some aspects of the spatial ecology of the species in this region remain unknown. In this study, 17 adult Cinereous Vultures were GPS-tracked in order to study their spatial ecology during the adult phase. The average monthly home ranges (95% Kernel Density Estimation, KDE) and core areas (50% KDE) were 6543 ​± ​19,935 ​km2 and 1174 ​± ​4004 ​km2, respectively. The average monthly home range fidelity ranged between 50 and 73%. Differences in movement-related variables between the seasonal periods (incubation, chick-rearing and non-breeding) were found. During the chick-rearing period, the monthly accumulated distance was higher than during the other periods: 3316 ​± ​1108 (chick-rearing) vs. 1621 ​± ​622 (incubation) vs. 1726 ​± ​1159 ​km per month (non-breeding). Additionally, large home range sizes were more frequent during the chick-rearing period. There are two likely causes for these seasonal differences. Firstly, chick-rearing entails a higher energetic expenditure by the parental individuals in foraging activities, so larger movements and foraging areas are expected during this period. Secondly, the flight is favoured during spring and summer due to environmental conditions. Matching chick-rearing and warm months is a great evolutionary advantage for soaring-gliding raptors, as it allows them to cover larger areas with low energy expenditure. Furthermore, six individuals tagged as nestlings highlight the philopatric behaviour of the species: vultures settle their breeding areas 54 ​± ​51 ​km from their natal nest (range ​= ​9–138 ​km).

Variations in home range and core area of red-backed voles (Myodes regulus) in response to various ecological factors

The characteristics of animal distribution are determined by interactions between the resource requirements of animals and ecological factors. This study sought to evaluate the effects of diverse ecological factors on the home range and core area of red-backed voles (Myodes regulus) in a natural deciduous forest located on Mt. Gariwang, Pyeongchang and Jeongseon, South Korea. Our study focused on four types of ecological factors: topography, climate, cover, and demography. A total of 29 voles were radio-tracked from August to September 2021. Home range (95% utilization distribution; UD) and core area (50% UD) were calculated using the kernel density estimator (KDE). The home range (1659.49 m2) and core area (317.08 m2) were negatively affected by altitude. The lunar phase and temperature negatively and positively influenced the home range and core area, respectively. The home range was positively affected by understory vegetation, whereas the core area was not. The core area increased within microhabitats with a high density of conspecific individuals, with males having a larger home range (2006.19 m2) and core area (375.40 m2) than females (1043.13 m2 and 213.39 m2, respectively). These findings provide a deeper understanding of the diverse ecological factors affecting the distributions of animals, especially small rodents.

Severe environmental conditions create severe conflicts: A novel ecological pathway to extreme coyote attacks on humans

Abstract Identifying the circumstances and causes of carnivore attacks on humans is important for prevention of future incidents as well as employing effective wildlife management strategies. Cape Breton Highlands National Park (CBHNP) in Nova Scotia has experienced multiple attacks by coyotes Canis latrans on humans, including a fatal attack on an adult in 2009. Here we use a combination of data on space use and diet collected from 2011 to 2013 to reveal that limited resources and a reliance on a large ungulate (moose, Alces americanus) as the mechanism leading to aggression by coyotes in CBHNP. Resident coyotes exhibited large home range sizes (mean = 77.5 km2) indicative of limited resources and spatiotemporal avoidance of human activity. Carbon (δ13C) and nitrogen (δ15N) isotope values of sub‐sampled coyote whiskers (n = 32), which provide a longitudinal record of diet over the months before collection, revealed little intra‐ and inter‐individual variation with nearly all individuals specializing on moose, a pattern that agrees with indices of natural resource availability. Specifically, stable isotope mixing models show that moose was the most important prey for most coyotes (25/32), representing between 41% and 78% of dietary inputs. Only four coyotes exhibited use of anthropogenic resources (human foods), and only one of seven coyotes involved in attacks on people had been consuming human foods before the attacks. Synthesis and Applications: We have described a unique ecological system in which a generalist carnivore has expanded its niche to specialize on a large prey species, with the unfortunate consequence of also expanding pathways to conflicts with people. Our results suggest extreme unprovoked predatory attacks by coyotes on people are likely to be quite rare and associated with unique ecological characteristics. Extreme management actions such as bounties are unnecessary, but managers may need to employ hazing or lethal removal earlier in the conflict process than under normal circumstances. Also, users of these areas should be made aware of the risks coyotes pose and encouraged to take precautions.

Seasonal home range and habitat selection patterns of sika deer Cervus nippon in southern Hokkaido, Japan

In 1980 and 1981, eight and nine individual sika deer Cervus nippon were reintroduced in southern Hokkaido, Japan, respectively, to address population declines in this species during 1900s. As recent population growth has led to human–wildlife conflicts, this study investigated the responses of sika deer to resource availability and geomorphic factors during the summer and winter seasons in southern Hokkaido. Global positioning system‐collared data collected from 2016 to 2018 were used to assess the home range patterns and habitat selection of 14 female sika deer located in Mount Esan and Shiriuchi. The core home range size was defined using a 50% kernel density estimation that indicated a larger home range in winter than summer for all deer. Habitat selection was assessed using generalized linear mixed models. The results showed variation in habitat selection between resident deer of Mount Esan and Shiriuchi, as well as migratory deer in Shiriuchi during summer. Resident deer in Mount Esan and Shriuchi preferred areas closer to crops during summer. Interaction effects revealed that migratory deer utilized natural grassland close to forest edge habitat in Shiriuchi. By contrast, resident deer in Shiriuchi selected forest edge habitat and natural grasslands close to crops. In winter, low elevation was the most important habitat factor for all deer across the study area. Thus, sika deer habitat selection depends on resource availability in summer and topographic factors in the winter.

Recovery and Germination of Malus sieversii (Ledeb.) M. Roem. (Rosaceae) Seeds after Ingestion by Cattle, Horses, and Sheep

Livestock can transport seeds long distances by endozoochory due to their large home range and capacity to move among different habitats. However, differences in digestive system and body size between different livestock species may result in variations in the dispersal of domestic livestock. To test such effects, we explore the effects of endozoochorous seed dispersal of Malus sieversii by three livestock: cattle, horse, and sheep in the Ili Botany Garden, northwest of China. We collected seeds of M. sieversii and fed them to cattle, horses and sheep. After feeding, we collected all the seeds from their feces every 24 h for 6 days and determined the seed recovery percent, mean retention time, and germination percent of seeds after the effects of the digestive tracts of those three livestock species. Seed recovery percent in three livestock species feces were cattle (CS) (54.05%) > horse (HS) (4.83%) > sheep (SS) (0.45%). The mean retention time of seeds in the digestive tract of cattle, horses and sheep were 53 h, 57 h, and 45 h. The seed weight and seed coat thickness decreased significantly after the treatment of the digestive tract. After 80 days cold stratification of seeds, the germination percent of CK, CS, and HS were 61%, 69%, and 18%, respectively. The results indicated cattle is an effective seed disperser of M. sieversii, with a recovery and germination percent in endozoochorous seed dispersal by cattle than that of horse and sheep. Our findings may also provide a theoretical basis about regarding seed-centric grazing management decisions and keeping horse and sheep out of pastures during the fruit of M. sieversii shedding period.

The Distribution and Community's Perception of Flying Fox, Pteropus vampyrus in Limbang, a Transboundary Area in Sarawak.

Flying foxes are threatened throughout their geographic range, and there are large gaps in the understanding of their landscape-scale habitat use. This study identified potential habitats in Limbang, Sarawak and informed potential distribution based on dispersal and interview surveys. Here, biological surveys were combined with interviews of local communities in Limbang Mangrove National Park (LMNP), Sarawak to illustrate distribution and the communities' perception on the protected flying fox (Pteropus vampyrus). Mangrove forest areas were surveyed for for the presence of flying foxes and villagers were interviewed regarding the use by flying foxes of agricultural areas and instances of conflict. Boat and questionnaire surveys were conducted for nine days from 18 to 27 February 2021. The surveys did not record any flying fox roosting sites within the national park and was instead observed to fly from Menunggul Island, Brunei into the national park in the evenings and back to Brunei in the mornings. A total of 27 flying foxes were recorded during the boat survey. Flying foxes were detected from 8/154 survey points and their spatial distribution appeared to be concentrated along Sungai Limpaku Pinang. Most respondents were aware of the species while some have directly observed them in fruit orchards, mangroves, rivers and mixed dipterocarp forests. Eleven perception-based questions were presented, and results showed that locality and income were the most influential parameters exhibiting conservation awareness through Boosted Regression Trees (BRT) analysis. Most respondents believe that flying foxes can uplift the local economy through ecotourism opportunities. However, these findings need to be carefully interpreted as the species has a large home range. Hence, long-term monitoring should be established to generate a larger dataset for stronger analysis to better represent the distribution and occurrence of this species in LMNP.

Benchmarking eleven biodiversity indicators based on environmental DNA surveys: More diverse functional traits and evolutionary lineages inside marine reserves

Abstract To mitigate the ongoing threats to coastal ecosystems, and the biodiversity erosion they are causing, marine‐protected areas (MPAs) have emerged as powerful and widespread conservation tools. Strictly no‐take MPAs, also called marine reserves, undeniably promote fish biomass and density, but it remains unclear how biodiversity responds to protection. Identifying which facets of biodiversity respond to protection is critical for the management of MPAs and the development of relevant conservation strategies towards the achievement of biodiversity targets. We collected 99 environmental DNA (eDNA) samples inside and outside nine marine reserves in the Mediterranean Sea to assess the effect of protection on 11 biodiversity indicators based on fish traits, phylogeny and vulnerability to fishing. We controlled for the effect of environmental heterogeneity (habitat, bathymetry, productivity, temperature and accessibility) using a principal component analysis, and for spatial autocorrelation due to potential unmeasured factors. We found a positive and significant effect of protection on only 3 out of 11 indicators: functional and phylogenic diversity but also the ratio between demerso‐pelagic and benthic species richness. Rather, total fish richness responded significantly and negatively to protection. We did not detect any significant effect of protection on threatened and elasmobranch species richness, probably due to their large home range compared to the size of Mediterranean marine reserves. Synthesis and applications: Our findings highlight the importance of looking beyond the mere number of species to fully depict and understand the effect of marine reserves on biodiversity and evaluate the effectiveness of conservation measures. Rather, we propose a dashboard of three eDNA‐based indicators that can provide an early signal of ecosystem deterioration or recovery. eDNA metabarcoding offers a powerful tool to supply site‐specific and standardized taxonomic‐, phylogenetic‐ and trait‐based biodiversity assessments, in complement to other classical techniques, such as visual censuses or video surveys, able to estimate species abundance but also individual life‐stage and size.

Down a Rabbit Hole: Burrowing Behaviour and Larger Home Ranges are Related to Larger Brains in Leporids

Studies on the evolution of brain size variation usually focus on large clades encompassing broad phylogenetic groups. This risks introducing ‘noise’ in the results, often obscuring effects that might be detected in less inclusive clades. Here, we focus on a sample of endocranial volumes (endocasts) of 18 species of rabbits and hares (Lagomorpha: Leporidae), which are a discrete radiation of mammals with a suitably large range of body sizes. Using 60 individuals, we test five popular hypotheses on brain size and olfactory bulb evolution in mammals. We also address the pervasive issue of missing data, using multiple phylogenetic imputations as to conserve the full sample size for all analyses. Our analyses show that home range and burrowing behaviour are the only predictors of leporid brain size variation. Litter size, which is one of the most widely reported constraints on brain size, was unexpectedly not associated with brain size. However, a constraining effect may be masked by a strong association of litter size with temperature seasonality, warranting further study. Lastly, we show that unreasonable estimations of phylogenetic signal (Pagel’s lamba) warrant additional caution when using small sample sizes, such as ours, in comparative studies.

The natural history and ecology of melanism in red wolf and coyote populations of the southeastern United States – evidence for Gloger’s rule

BackgroundGloger’s rule postulates that animals should be darker colored in warm and humid regions where dense vegetation and dark environments are common. Although rare in Canis populations, melanism in wolves is more common in North America than other regions globally and is believed to follow Gloger’s rule. In the temperate forests of the southeastern United States, historical records of red wolf (Canis rufus) and coyote (Canis latrans) populations document a consistent presence of melanism. Today, the melanistic phenotype is extinct in red wolves while occurring in coyotes and red wolf-coyote hybrids who occupy the red wolf's historical range. To assess if Gloger’s rule could explain the occurrence and maintenance of melanistic phenotypes in Canis taxa, we investigated differences in morphology, habitat selection, and survival associated with pelage color using body measurements, GPS tracking data, and long-term capture-mark-recapture and radio-telemetry data collected on coyotes and hybrids across the southeastern United States.ResultsWe found no correlation between morphometrics and pelage color for Canis taxa. However, we observed that melanistic coyotes and hybrids experienced greater annual survival than did their gray conspecifics. Furthermore, we observed that melanistic coyotes maintained larger home ranges and exhibited greater selection for areas with dense canopy cover and wetlands than did gray coyotes.ConclusionsIn the southeastern United States, pelage color influenced habitat selection by coyotes and annual survival of coyotes and hybrids providing evidence that Gloger’s rule is applicable to canids inhabiting regions with dense canopy cover and wetlands. Greater annual survival rates observed in melanistic Canis may be attributed to better concealment in areas with dense canopy cover such as coastal bottomland forests. We suggest that the larger home range sizes of melanistic coyotes may reflect the trade-off of reduced foraging efficiency in lower quality wetland habitat for improved survival. Larger home ranges and differential use of land cover by melanistic coyotes may facilitate weak assortative mating in eastern coyote populations, in which melanistic animals may have lower success of finding compatible mates in comparison to gray conspecifics. We offer that our observations provide a partial explanation for why melanism is relatively low (< 10%) but consistent within coyote populations throughout southeastern parts of their range.

Nocturnal space and habitat use by Garden Dormice in an urban area in Germany

The Garden Dormouse (Eliomys quercinus) is currently disappearing from parts of its former range. While its population is declining in many parts of Germany, a stable occurrence is found in the city of Wiesbaden. A radio telemetry study was conducted to investigate nocturnal activity and habitat use. Three males and one female were tracked for six weeks from May to July 2021. Males weighed 85 ± 15 g (n = 6), females 63 ± 8 g (n = 2). Home ranges were calculated using the minimum convex polygon (MCP) method. Males had larger home range sizes (MCP100: 2.69 ± 1.8 ha, n = 3) than females (0.53 ha, n = 1). The home ranges of males overlapped. Males regularly crossed roads up to 16 m wide. Animals exhibited nocturnal behavior with sporadic activity at dusk. Garden Dormice preferred structures with more than 75 % cover from a bird's eye view and 50 % cover when viewed from the side. Broad hedges were strongly preferred over single shrubs and trees or structures without vegetation. They were used by the animals for foraging, mating, as a place for other interactions, and as protected pathways through the habitat. The smaller home range sizes compared to previous studies may be due to good food availability in the city. Animals also seem to benefit from continuous habitat and high levels of plant cover. Recommended conservation measures include maintaining and promoting broad hedges and habitat connectivity.

Predicting the risk of Alaria alata infestation in wild boar on the basis of environmental factors.

Alaria alata is an emerging parasite that poses a potential risk for those consuming game, pork, snails and frogs. One paratenic host of A. alata that is known to play an important role in its spread through its feeding habitats is the wild boar. However, no statistical analysis of the influence of aquatic environments and carnivores on the occurrence of A. alata in wild boars has yet been performed. The present study combines a small-scale analysis based on hunting districts in the Mazowieckie province with a large-scale analysis based on data for all provinces in Poland. We applied various modeling approaches, including logistic regression and a generalized linear model in order to determine the presence, intensity and prevalence of A. alata. We used the Alaria mesocercariae migration technique (AMT) to estimate the risk of A. alata among wild boar in a given hunting district or province. The small-scale analysis found that mesopredators (red fox (Vulpes vulpes)) and racoon dog (Nyctereutes procyinoides) were likely to influence A. alata infestation of wild boar; however, the effect was weak, probably as a result of the large home range size of these animals. The large-scale analysis found that wetlands influence the prevalence of A. alata in wild boar, with the estimated risk increasing in the north of the country; this finding is consistent with other studies. Our findings indicate that the occurrence of A. alata in wild boar requires analysis on many levels, and environmental factors play a key role in risk assessment.

A case of polygyny in the Bornean white-bearded gibbon (Hylobates albibarbis)

Abstract Gibbons (family Hylobatidae) typically form groups that encompass a single breeding pair. Here, we present the first evidence of polygyny (where a single male has more than one female mate) in the Bornean white-bearded gibbon (Hylobates albibarbis). In July 2014, an adult female yet to have emigrated from her natal group gave birth to an infant, bringing the total group size to six individuals (one adult male, two adult females, one subadult female, and two infant females). Forty months later in November 2017, the same female gave birth to a second infant. Between July 2014 and April 2018, the two breeding females within the group remained mutually tolerant of each other, often singing the characteristic female vocalisation, the great call, in unison, until the eldest adult female dispersed in November 2018. We explore possible reasons behind this group’s mating system flexibility by examining dispersal limitation due to environmental constraints, factors associated with a large home range size, mutual tolerance between females, and a lack of mating opportunities.

Ectoparasite load of small mammals in the Serengeti Ecosystem: effects of land use, season, host species, age, sex and breeding status

Ectoparasite load in small mammals can be influenced by both environmental conditions and host species characteristics. However, the nature of these influences is poorly understood in many ecosystems. We used zero-inflated negative binomial (ZINB) regression models with a log link function to assess variation in ectoparasite load among 19 small mammal host species across different land uses (protection in a park, pastoralism and agriculture), habitat types, seasons, age classes, sexes and breeding statuses. We collected 4258 ectoparasites from 612 individual belonging to 19 different species of small mammals. The average ectoparasite load per individual was higher in the pastoral and agricultural lands than in the National Park. Ectoparasite load varied among species and was the highest for the four common and generalist small mammal species (Aethomys sp., Arvicanthis niloticus, Mastomys natalensis, and Gerbilliscus vicinus), most notably in the disturbed pastoral and agricultural lands. It was also higher in the dry than the wet season and for adult males than adult females. These patterns partly reflect the greater mobility of small mammals in the drier conditions; in addition the large body size and home range of males increase the likelihood of encountering parasites. Human disturbance was associated with elevated ectoparasitic load among the small mammals and hence elevated risk of transmission of ectoparasites to humans. As a result, understanding the effect of habitat disturbance on ectoparasite load and its link to zoonotic disease risk should be an important conservation goal and public health priority. Moreover, effective pest control strategies should consider variation in ectoparasite load with land use, habitat type, season and species characteristics.

Wildfire response of GPS-tracked Bonelli’s eagles in eastern Spain

Background Little is known about the interaction between predators and wildfires, in part because the large home range and scarcity of predators make their study difficult, and their response is strongly species-specific. Aims In this paper, we study, for the first time, the effect of wildfire on the behaviour of Bonelli’s eagles (Aquila fasciata) simultaneously tracked by GPS/GSM dataloggers in four neighbouring territories. Methods One territory was burnt in a wildfire and the other three were used for comparison. We computed the home-range area by comparing individual spatial and temporal behaviour before, during and after the fire event using kernel density estimators and movement parameters. Key results Our results show an immediate negative effect during the first days of the wildfire for an individual inhabiting the burnt territory – the individual flew directly away from the burning area. However, after a few days, the individual recovered their usual behaviour. The three neighbouring pairs did not show significant differences in behavioural parameters before, during and after the wildfire. Conclusions and implications Our results suggest that occasional wildfires do not affect the distribution and density of Bonelli’s eagles in the short or medium-term (two years after fire). This could be the result of adaptation by this species to the frequent and recurrent wildfires in the Mediterranean area.

Field metabolic rates of giant pandas reveal energetic adaptations

Knowledge of energy expenditure informs conservation managers for long term plans for endangered species health and habitat suitability. We measured field metabolic rate (FMR) of free-roaming giant pandas in large enclosures in a nature reserve using the doubly labeled water method. Giant pandas in zoo like enclosures had a similar FMR (14,182 kJ/day) to giant pandas in larger field enclosures (13,280 kJ/day). In winter, giant pandas raised their metabolic rates when living at − 2.4 °C (36,108 kJ/day) indicating that they were below their thermal neutral zone. The lower critical temperature for thermoregulation was about 8.0 °C and the upper critical temperature was about 28 °C. Giant panda FMRs were somewhat lower than active metabolic rates of sloth bears, lower than FMRs of grizzly bears and polar bears and 69 and 81% of predicted values based on a regression of FMR versus body mass of mammals. That is probably due to their lower levels of activity since other bears actively forage for food over a larger home range and pandas often sit in a patch of bamboo and eat bamboo for hours at a time. The low metabolic rates of giant pandas in summer, their inability to acquire fat stores to hibernate in winter, and their ability to raise their metabolic rate to thermoregulate in winter are energetic adaptations related to eating a diet composed almost exclusively of bamboo. Differences in FMR of giant pandas between our study and previous studies (one similar and one lower) appear to be due to differences in activity of the giant pandas in those studies.

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

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

Estimating encounter location distributions from animal tracking data

AbstractEcologists have long been interested in linking individual behaviour with higher level processes. For motile species, this ‘upscaling’ is governed by how well any given movement strategy maximizes encounters with positive factors and minimizes encounters with negative factors. Despite the importance of encounter events for a broad range of ecological processes, encounter theory has not kept pace with developments in animal tracking or movement modelling. Furthermore, existing work has focused primarily on the relationship between animal movement and encounterrateswhile the relationship between individual movement and the spatiallocationsof encounter events in the environment has remained conspicuously understudied.Here, we bridge this gap by introducing a method for describing the long‐term encounter location probabilities for movement within home ranges, termed the conditional distribution of encounters (CDE). We then derive this distribution, as well as confidence intervals, implement its statistical estimator into open‐source software and demonstrate the broad ecological relevance of this distribution.We first use simulated data to show how our estimator provides asymptotically consistent estimates. We then demonstrate the general utility of this method for three simulation‐based scenarios that occur routinely in biological systems: (a) a population of individuals with home ranges that overlap with neighbours; (b) a pair of individuals with a hard territorial border between their home ranges; and (c) a predator with a large home range that encompassed the home ranges of multiple prey individuals. Using GPS data from white‐faced capuchinsCebus capucinus, tracked on Barro Colorado Island, Panama, and sleepy lizardsTiliqua rugosa,tracked in Bundey, South Australia, we then show how the CDE can be used to estimate the locations of territorial borders, identify key resources, quantify the potential for competitive or predatory interactions and/or identify any changes in behaviour that directly result from location‐specific encounter probability.The CDE enables researchers to better understand the dynamics of populations of interacting individuals. Notably, the general estimation framework developed in this work builds straightforwardly off of home range estimation and requires no specialized data collection protocols. This method is now openly available via thectmm Rpackage.

Varying genetic imprints of road networks and human density in North American mammal populations.

Road networks and human density are major factors contributing to habitat fragmentation and loss, isolation of wildlife populations, and reduced genetic diversity. Terrestrial mammals are particularly sensitive to road networks and encroachment by human populations. However, there are limited assessments of the impacts of road networks and human density on population‐specific nuclear genetic diversity, and it remains unclear how these impacts are modulated by life‐history traits. Using generalized linear mixed models and microsatellite data from 1444 North American terrestrial mammal populations, we show that taxa with large home range sizes, dense populations, and large body sizes had reduced nuclear genetic diversity with increasing road impacts and human density, but the overall influence of life‐history traits was generally weak. Instead, we observed a high degree of genus‐specific variation in genetic responses to road impacts and human density. Human density negatively affected allelic diversity or heterozygosity more than road networks (13 vs. 5–7 of 25 assessed genera, respectively); increased road networks and human density also positively affected allelic diversity and heterozygosity in 15 and 6–9 genera, respectively. Large‐bodied, human‐averse species were generally more negatively impacted than small, urban‐adapted species. Genus‐specific responses to habitat fragmentation by ongoing road development and human encroachment likely depend on the specific capability to (i) navigate roads as either barriers or movement corridors, and (ii) exploit resource‐rich urban environments. The nonuniform genetic response to roads and human density highlights the need to implement efforts to mitigate the risk of vehicular collisions, while also facilitating gene flow between populations of particularly vulnerable taxa.