Den Sites Research Articles

The underground cat: burrow use by female black-footed cats (Felis nigripes)

The black-footed cat (Felis nigripes) is the smallest and one of the rarest cats in Africa. Endemic to the semi-arid regions of South Africa, Namibia and Botswana, this nocturnal carnivore spends daytime in burrows, thus avoiding high temperatures and diurnal predators. Despite the importance of burrows, den usage has never been studied in detail for this species. Here we report on the frequency with which female black-footed cats use burrows of different dimensions and compared with burrow availability. The entrances of 50 dens, used by five radio-collared black-footed cats over four weeks, were scanned with LiDAR to measure tunnel width (mean = 15.2 ± 3.9 cm) and height (mean = 13.9 ± 3.6 cm). Of these, 98% (n = 49) most closely matched the dimensions of springhare (Pedetes capensis) burrows. Each cat used a mean of 11.6 den sites and spent a mean of 2.0 consecutive days in a den before selecting a new one. When kittens reached an age of 44–50 days, mothers switched from using a den for a mean of six days-per-den, to changing dens every day. Our results suggest that female black-footed cats are reliant upon springhares to provide suitable daytime refugia and maternity dens in southern Namibia. Further studies should be conducted to determine what den sites are selected in the absence of springhare, and whether localised persecution of springhare impacts the survival of black-footed cats.

Resource selection of den sites for bobcats (Lynx rufus) in the Northern Great Plains, United States

Abstract Dens play a crucial role in the survival of young and can ultimately affect population dynamics for felid carnivores. However, little is known about Bobcat (Lynx rufus) den site selection. Therefore, this study aimed to identify environmental correlates of Bobcat den sites in the Black Hills, South Dakota, United States. Our objectives for this study were to compare environmental characteristics of Bobcat dens to random sites at coarse (3.14 ha) and local (0.05 ha) spatial scales. Female bobcats were radio-collared (n = 35) and dens (n = 27) were located using ground telemetry. Bobcats selected for high horizontal cover and terrain ruggedness at the coarse scale, as well as high horizontal cover at the local scale, which could provide concealment from predators. In less rugged areas land management practices that promote increased tree and shrub habitat as horizontal cover may provide habitat for Bobcat dens and ensure the survival of this ecologically and culturally important species.

Variable persistence of an iconic arboreal mammal through the Black Summer wildfires

Wildfires are predicted to increase in frequency and severity with climate change but detailed understanding of their influence on forest wildlife is lacking for many species. Wildfires vary in their extent and severity among landscapes, limiting generalisations about impacts from a single wildfire. We investigated post-wildfire persistence in the threatened exudivorous yellow-bellied glider (Petaurus australis) in south-eastern Australia. The widespread occurrence of wildfires in the ‘Black Summer’ of 2019–20 enabled populations in three landscapes (90–160 km apart) to be studied. This species has a slow life history (one young per year and >1 year to mature) so post-fire recovery is predicted to be slow. We conducted repeat surveys over 3 years post-fire in each landscape at 25–29 sites that were occupied pre-wildfire. All survey sites were burnt in two landscapes but only 40 % were burnt in the third. We estimated declines in occupancy of 13 %, 40 % and 66 % in burnt forest. The factors driving the variation in decline appear to be a combination of fire severity and the abundance of very large (≥80 cm) hollow (i.e. cavity) -bearing trees that serve as den sites. The implications of this study are that the impacts of wildfires on populations of tree-hollow dependent species can be expected to vary in different landscapes as a consequence of fire severity, rainfall deficit and logging history. Our study suggests the importance of ensuring populations are conserved across a wide geographic gradient, and the value of very large hollow-bearing trees rather than simply the number of any hollow-bearing trees.

Selection of den sites and chronology of denning by black bears in the eastern Sierra Nevada and western Great Basin.

Use of dens during winter is an important strategy for American black bears (Ursus americanus) for both energy conservation and reproduction; and occupancy of suitable den sites has implications for reproductive fitness. Denning strategies may change as a result of changing climatic conditions and habitat loss. Black bears occupy arid environments in the eastern Sierra Nevada and the western ranges of the Great Basin Ecosystem. Our objectives were to identify: (1) which physical characteristics of habitat influenced selection of den sites at multiple spatial scales and (2) which environmental factors influenced timing of entrance and exit of dens by females and males. We evaluated selection of den sites by black bears at three spatial scales (300, 1000, and 4000 m) from 2011 to 2022. Terrain ruggedness was important for selection of den sites at all spatial scales. Within a 300-m buffer from the den, bears selected den sites with rugged terrain, lower horizontal visibility, and greater canopy cover, resulting in more concealment and protection than that of the surrounding environment. Within 1000- and 4000-m buffers around each den, bears selected den sites with rugged terrain, northern aspects, and steep slopes. At the 4000-m scale, we observed interactions between sex with slope and distance to roads; females selected den sites on steeper slopes and closer to roads than did males. Females remained in the dens longer than males by entering earlier in the autumn and exiting later in the spring. Male bears exited their dens earlier with increasing consecutive days above freezing temperatures, but that relationship was weak for females. Knowing what characteristics are important for selection of den sites, and influence timing of denning, will be important for understanding how shifting climatic patterns will affect bears, particularly in arid environments that may be prone to wider fluctuations in climatic drivers of denning in the future.

There is no place like home: Den and rendezvous site selection of Indian wolves in the human-dominated landscape of Maharashtra

There is no place like home: Den and rendezvous site selection of Indian wolves in the human-dominated landscape of Maharashtra

Lightweight den boxes enhance habitat for pine martens Martes martes in a conifer plantation in south-west Scotland

The European pine marten Martes martes typically occupies woodland and preferentially rests and breeds in arboreal, insulated den sites, which are particularly critical for breeding females. An absence of elevated cavities may force pine martens to use suboptimal den sites, and consequently limit population distribution, abundance, and breeding success. Artificial den boxes have been designed and installed in recent years and occupied by both non-breeding and breeding pine martens. However, the large size and weight of these boxes makes them too heavy to use in young forestry plantations. We tested two smaller, lighter box designs (the Galloway Lite Mk1 (‘GLMk1’) and Galloway Lite Mk2 (‘GLMk2’)) that could be more easily deployed in commercial conifer plantations. Fifty boxes of each design were installed in Galloway Forest, south-west Scotland, and monitored for evidence of pine marten occupation and breeding. Overall, GLMk2 boxes were occupied more frequently than the GLMk1 boxes, including for breeding. The Galloway Lite boxes provide a lightweight, economical and practical option for increasing the availability of elevated den sites for pine martens and can be deployed as a conservation tool to enhance habitat conditions.

Lightweight den boxes enhance habitat for pine martens Martes martes in a conifer plantation in south-west Scotland

The European pine marten Martes martes typically occupies woodland and preferentially rests and breeds in arboreal, insulated den sites, which are particularly critical for breeding females. An absence of elevated cavities may force pine martens to use suboptimal den sites, and consequently limit population distribution, abundance, and breeding success. Artificial den boxes have been designed and installed in recent years and occupied by both non-breeding and breeding pine martens. However, the large size and weight of these boxes makes them too heavy to use in young forestry plantations. We tested two smaller, lighter box designs (the Galloway Lite Mk1 (‘GLMk1’) and Galloway Lite Mk2 (‘GLMk2’)) that could be more easily deployed in commercial conifer plantations. Fifty boxes of each design were installed in Galloway Forest, south-west Scotland, and monitored for evidence of pine marten occupation and breeding. Overall, GLMk2 boxes were occupied more frequently than the GLMk1 boxes, including for breeding. The Galloway Lite boxes provide a lightweight, economical and practical option for increasing the availability of elevated den sites for pine martens and can be deployed as a conservation tool to enhance habitat conditions.

Mesocarnivores den site selection in arid ecosystems; A case study of Rüppell's fox and sand cat in central Iran

Understanding the relationships between species and their pattern of coexistence is essential in conservation planning. Rüppell's fox and sand cat are two poorly known species of desert areas that coexist in most parts of the desert belt of Africa and the Middle East. However, their habitat selection in many parts of their distribution are unknown. In this research, using the data collected from a three-year monitoring plan, we investigated the relationship between the den sites of Rüppell's fox and sand cat and habitat variables based on the generalized linear mixed model (GLMM) method. The results showed that for Rüppell's foxes, only the density of rodent burrows had a significant and positive effect. In the sand cat model, in addition to prey, vegetation density (P-value < 0.05) and vegetation height (P-value < 0.10) had significantly positive effects and elevation had a significantly negative effect (P-value < 0.10). We found that the sand cat is more specialized in habitat selection and depends more on the habitat cover. While the Rüppell's fox chose a more diverse range of soil and vegetation classes, the sand cat selected its den sites exclusively in sandy loam soils with the predominant cover of Haloxylon spp. and Caligonum spp. Acting as a generalist species, Rüppell's fox displayed a more pronounced response to human presence and selected dens with a broader view of their surroundings. These findings enhance our understanding of mesocarnivore coexistence in desert regions and provide valuable insights for the conservation planning of these species.

Ecology Of Bengal Fox (Vulpes Bengalensis) In Northwest Bangladesh

The northwest regions of Bangladesh belong to the global range of Bengal fox, Vulpes bengalensis. However, scientific information on this small canid in Bangladesh is scanty; it also remains out of any conservation initiatives, and it is widely perceived as a potential threat to local poultry. We conducted this premier study between September 2019 and December 2021. We investigated the feeding and breeding behaviour of this fox by using scat samples, direct field surveys and camera-trapping. An analysis of 67 scats yielded eight major categories of prey items consumed by the fox. Arthropods (29%) ranked top in the relative percentage of occurrence, followed by rodents (27%), plant parts (17%), and birds (13%), among the others. Ninety-two percent of scats contained multiple food items, with an average number of food items per scat of 3.50± SE 1.87. We recorded 17 den sites in and around human-dominated landscapes, of which nine den sites remained unoccupied during the entire study period. Dens used by Bengal foxes were complex, comprising interconnected tunnels and holes with an average of 23.66± SD 12.78 holes/den. We estimated a total of 37 individuals of the fox, with 62% pups in the recorded population. The average litter size was 3.36± SE 0.52 pups. We recommend further research to assess population status and delineate its range in Bangladesh. Bangladesh J. Zool. 51(1): 35-45, 2023

Increased bat activity at urban water sources: implications for cross-species transmission of bat rabies to mesocarnivores

AbstractWe examined the potential for urban water sources, specifically golf course ponds, to act as centers for rabies transmission from bats to mesocarnivores in the arid southwestern United States where surface water is often limited. Because residential housing can act as den and roost sites for both mesocarnivores and bats, we also examined the effect of housing density around water sources on activity. Using ultrasonic acoustic recorders to assess bat activity and camera traps to estimate mesocarnivore activity, we compared 14 pairs of wet and dry locations over two years by surveying twice during the summer, once prior to summer monsoons and once during the monsoon season, when surface waters were more available. Number of calls for all bat species combined were greater at wet sites compared to dry sites and calls of two bat species often associated with rabies, big brown bat (Eptesicus fuscus) and silver-haired bat (Lasionycteris noctivagans), were recorded more at wet sites than dry sites in the monsoon season. In both years, raccoons (Procyon lotor) were photographed more often at wet sites while striped skunks (Mephitis mephitis) and gray foxes (Urocyon cinereoargenteus) were less likely to be detected at wet sites. Bat, fox and raccoon activity was not associated with housing density while striped skunks showed a positive correlation. Finally, we examined potential for contact between mesocarnivores and big brown bats, a species implicated in cross-species rabies transmission in our area, by combining call activity of this bat species and photo detections of mesocarnivores during individual hours of the night into a Potential Contact Index (PCI) and found no significant effect of season (pre-monsoon vs. monsoon), species, or treatment (dry versus wet) but did find a significant species by treatment interaction, with raccoon PCI 3–30 times higher at wet sites and no effect on the other two mesocarnivores’ PCI. Overall, we found higher activity of bats at urban waters could increase potential for cross-species transmission of rabies from bats to raccoons but not for gray foxes and striped skunks.

Den site selection and seasonal changes in use patterns by the masked palm civet (Paguma larvata) in urban areas of Morioka City, Japan

Den site selection and seasonal changes in use patterns by the masked palm civet (Paguma larvata) in urban areas of Morioka City, Japan

Den site selection by eastern spotted skunks (Spilogale putorius) in the Blue Ridge Mountains, North Carolina

Den site selection by eastern spotted skunks (Spilogale putorius) in the Blue Ridge Mountains, North Carolina

Wolverine denning behaviour and its implications for monitoring reproductive females

Knowledge about the number of reproductive females is important for monitoring population dynamics, and can be critical for managing human–wildlife conflicts. For wolverines Gulo gulo, counts of reproductive females is the basis for estimates of population size in Scandinavia, as well as a key measure for compensation payments to Sámi reindeer‐herders in Sweden. However, documenting wolverine reproductive events in the field is challenging and requires knowledge of female denning behaviour. Furthermore, females may shift den sites, presenting difficulties in determining whether two den sites belong to the same or two neighbouring females. In this study, we used data from 18 GPS‐collared wolverine females, monitored intensively during the denning season (15 February–31 May) in 2004–2014, to provide baseline information on denning behaviour. We documented reproductive events in 32 of 54 potential denning seasons, and identified a total of 245 den sites. Females used 8.8 ± 8.5 (mean ± SD) den sites per denning season (median = 6, range: 1–28). The number of den site shifts, the distance between subsequent den sites, and the time and distance females spent away from a den site increased during the denning season; while distances between neighbouring females' den sites remained constant. From late April, the distance between consecutive den sites used by the same female overlapped with distances between neighbouring females' den sites, resulting in increased uncertainty regarding whether two den sites belonged to one or two females. Using Bayesian modelling we calculated probabilities that two den sites belonged to the same female, or neighbouring females, conditional on the time of season and the distance between den sites. These findings will allow the monitoring program to adapt its methods for determining if multiple den sites belong to one or two reproductive events, using seasonally‐dynamic threshold based on an understanding of wolverine denning behaviour.

First record of allonursing in golden jackal (Canis aureus, L. 1758): a case of double breeding and communal denning within the same social unit

In the last decade, there has been a remarkable increase in the number of scientific publications on the ecology of the golden jackal Canis aureus, whereas information on its reproductive biology is still scanty, and the basic reproductive parameters of the species are not yet fully understood. In 2021, we began a research project in North-Eastern Italy, where the golden jackal is strictly protected under the National Law, to investigate the species behavioural ecology and reproductive biology at the den site, as a key element for defining conservation measures. Within this project, we documented allosuckling behaviour, possibly related to the breeding of two females within the same social unit, with den sharing and communal nursing of the cubs. Our observations open new scenarios and raise questions on the reproductive biology and social organisation of the golden jackal, stimulating further topics for research.

Sloth Bear (Melursus ursinus) Maternity Denning Behavior Observations at Indira Gandhi Zoological Park, Visakhapatnam, India

The Sloth bear is an average-sized black bear with a long, shaggy coat. a long ruff of hair around the back, and a white V- or Y-shaped mark on the breast. Males that are considered to be "large" often top out around 145 kg and 170 centimeters. An endangered species, the sloth bear (Melursus ursinus) is extensively spread over the Indian subcontinent, including India, Nepal, Bhutan, Sri Lanka, and perhaps Bangladesh. It is found in wooded regions from the Indian peninsula to the foothills of the Himalayas. Despite the species' widespread occurrence, nothing is known about its ecology or behavior. We studied den characteristics and maternity denning behavior in captivity. The den use was more from June to August, possibly to take shelter against heavy rains from the southwest monsoon. (June - September). Breeding observed based on the association of adult females and males as well as the birth of cubs revealed that mating is likely to occur during late summer or early monsoon and cubs are born mostly during November-December. This study presents observations on den site characteristics and maternal denning behavior patterns of sloth bears in captivity at Indira Gandhi Zoological Park, Visakhapatnam.

Sloth bear maternal and resting den locations in eastern Karnataka

AbstractSloth bears (Melursus ursinus) use resting and maternal dens. Resting dens are used by both sexes, usually during the mid‐day when sloth bears are least active. Maternal dens are used by female bears to give birth and raise cubs. The purpose of our study was to better understand the denning ecology of sloth bears in eastern Karnataka so that important denning habitat can be delineated and protected. We documented resting and maternal dens from 2014 to 2018 in 5 different study areas surrounded by agriculture and orchards in eastern Karnataka, India. We used landscape and site‐specific variables to model the probability of den occurrence. The best fit model for approximating maternal den site selection included distance to forest border, protection level, aspect, slope, and elevation. The best fit model for approximating resting den site selection included distance to forest border, aspect, slope, protection level and ruggedness. Maternal dens were closer to forest borders than resting dens. We postulate that areas near the forest border are chosen for access to resources and that mothers choose dens closer to edges because of the constraints and needs of cubs. In poorly protected, resource‐deficient areas, selection of maternal dens near habitat edges presents a tradeoff between higher resource availability closer to human habitation, reduced risk of cub predation, and higher risk of human‐caused mortality compared to areas farther from forest borders. Resting and maternal dens were farther from forest borders in better‐protected areas, suggesting that if resources are prevalent in the habitat, bears would use locations farther from the forest borders.

A field test of R package GPSeqClus: For establishing animal location clusters

Abstract The ability to track animals with Global Positioning System (GPS) collars opened an enormous potential for studying animal movements and behaviour in their natural environment. One such endeavour is to identify clusters of GPS locations as a way to estimate predator kill rate. Clapp et al. (2021) developed an R package (GPSeqClus) to assess a location dataset based on user‐defined parameters to identify clusters and their characteristics. These characteristics can then help to distinguish resting‐site clusters from kill sites of their large (&gt;50 kg) prey. We identified location clusters of an adult male wolf Canis lupus on Ellesmere Island, Nunavut, Canada in July 2009 and tracked him until he died in April 2010. Identifying location clusters was challenging because the collar only obtained two GPS locations per day (12 h apart). In July 2010, we searched 30 of 52 location‐clusters we identified as kill/scavenge sites and found 17 of them as such, given they had muskox Ovibos moschatus or caribou Rangifer tarandus pearyi remains nearby. We also documented five wolf rendezvous sites, two den sites, and the wolf's death site to total 60 location‐clusters in all. We used a two‐step process in testing the R Package GPSeqClus (hereafter GPSeqClus): (1) compare the number of clusters our method discerned with the number identified by the new algorithm, and (2) compare the number of biologically significant clusters (e.g. den sites, kill/feeding sites) we found with the number the new algorithm located. We made these tests with GPSeqClus by varying the search radius, number of days at a site, and minimum number of locations required for a cluster. GPSeqClus compared well to our technique, with the best sub‐algorithm among the 25 we tested only missing three of our identified clusters and yielding six additional clusters. GPSeqClus identified 16 of the 17 confirmed sites of remains, all wolf home sites, and the wolf's carcass site. Identifying clusters using a 500‐m search radius, a 1.5‐day window, and a minimum of two GPS locations per cluster was suitable for a coarse GPS acquisition rate of two locations per day when prey are large, such as muskox or caribou. Given that GPSeqClus performed well with our coarse location dataset, we expect it will also perform even better with a collar acquiring more than two locations per day. Having a field‐tested utility such as GPSeqClus will enhance carnivore predation studies elsewhere.

Variation in adult and pup wolf diets at natal den sites is influenced by forest composition and configuration.

Although wolves are wide-ranging generalist carnivores throughout their life cycle, during the pup-rearing season wolf activity is focused on natal den sites where pup survival depends upon pack members provisioning food. Because prey availability is influenced by habitat quality within the home range, we investigated the relative importance of prey species for adults and pups and further examined the relationship between habitat characteristics, wolf diet, and litter size on Prince of Wales Island (POW) in Southeast Alaska. During 2012-2020, we detected 13 active den sites within the home ranges of nine wolf packs. We estimated minimum pup counts using motion-detecting cameras and individual genotypes from noninvasive samples (hair: n=322; scat: n=227) and quantified wolf diet composition using fecal DNA metabarcoding (n=538). We assessed habitat composition, configuration, and connectivity within denning and annual home ranges estimated using wolf GPS-collar data. Contrary to expectations, wolves had a more constricted diet during denning season (April 15-July 31), and within this season pups had a narrower dietary niche (species richness [S]=4) focused more on deer (relative frequency of occurrence [O/I]=0.924) than adults (S=15; deer O/I=0.591). Litter size had a positive relationship with the relative frequency of deer in a wolf pack's diet. Wolf consumption of deer was positively associated with the proportion of young-growth forest (≤25 years old) within denning and annual home ranges. High levels of vegetation patch interspersion, and the density of closed logging roads were also important predictors, suggesting these habitat qualities were influential for increasing the availability of deer to wolves. Our results contrast with previous research indicating wolf pup diets included more alternate prey (i.e., beaver) than adults and emphasize the importance of deer to wolf viability on POW, especially during denning season.

Seven urgent actions to prevent the extinction of the critically endangered Leadbeater’s possum (Gymnobelideus leadbeateri)

The conservation status of Leadbeater’s possum (Gymnobelideus leadbeateri) was upgraded to ‘Critically Endangered’ in 2015 following major impacts on populations and habitat arising from the ‘Black Saturday’ bushfires of 2009. This conservation listing was subsequently reviewed and retained in 2019. Despite this recognition of significant extinction risk, major gaps exist in the conservation strategy being applied, including the absence of a current recovery plan or meaningful recovery targets. The cumulative impacts and legacies on forest condition and hollow-bearing tree abundance from logging and bushfire pose the most significant threats to the species, and several studies indicate that the current reserve system is inadequate to protect viable populations. Seven high-level actions are recommended that should be implemented with urgency to prevent the extinction of this iconic, flagship species amidst increasing threats from climate change. Most significantly, this includes the rapid phase-out of logging within the species’ range as the highest priority action. Other urgent measures include re-formation of a recovery team to coordinate action implementation, provision of nest boxes and chainsaw hollows to increase den site availability, intensive population management and habitat restoration for the lowland population that now contains fewer than 40 individuals, and translocations to expand the area of occupancy in response to increasing risks from bushfire and climate change.

GRIZZLY BEAR DENNING HABITAT AND DEMOGRAPHIC CONNECTIVITY IN NORTHERN IDAHO AND WESTERN MONTANA

Grizzly Bears (Ursus arctos) are protected in the contiguous United States under the federal Endangered Species Act. The conservation strategy for the species encourages population connectivity between isolated Grizzly Bear Recovery Areas through Demographic Connectivity Areas. Another goal is reestablishment of a breeding population in the Bitterroot ecosystem through natural immigration. Using the locations of 362 verified Grizzly Bear den sites and Maxent as a resource selection function, we predicted 21,091 km2 of suitable denning habitats. Terrain features, distance to roads, and land cover best explained suitable denning habitats in northern Idaho and western Montana. The results support the demographic model for population connectivity, and independent of other factors there is suitable denning habitat for hundreds of Grizzly Bears in the Bitterroot analysis area. We suggest additions to the Bitterroot Grizzly Bear Recovery Area, and that more effective motorized-access management be applied to demographic connectivity areas.