Den Entrance Research Articles

Comparison of San Joaquin kit fox den and California ground squirrel burrow attributes

Endangered San Joaquin kit foxes (Vulpes macrotis mutica; SJKF) and California ground squirrels (Otospermophilus beecheyi; CAGS) occur sympatrically in many locations. CAGS can constitute a nuisance species and control strategies have included lethal measures administered within CAGS burrows. These measures could harm or kill a SJKF if mistakenly applied to an occupied SJKF den. To identify attributes to distinguish between SJKF dens and CAGS burrow, we assessed dimensions, penetration depths by 9.7-cm and 7.5-cm spheres, ejecta patterns, and the presence of various types of sign at 65 dens to which radiocollared SJKF were tracked and at 80 burrows that CAGS were observed to enter. Mean entrance height, width, and circumference all were significantly larger for SJKF den entrances. However, the ranges of values for all dimensions for the CAGS burrows completely encompassed the ranges for the SJKF dens. Penetration depths with the 7.5-cm sphere were similar for SJKF dens and CAGS burrows. The 9.7-cm sphere could not be inserted in over half of CAGS burrows and exceeded 1 m in depth in over half of the SJKF dens. Most SJKF dens had dirt berms but so did over half of the CAGS burrows. SJKF scats, prey remains, CAGS scats, and trash were observed at both SJKF dens and CAGS burrows although at different frequencies. CAGS tracks were only observed at seven CAGS burrows. None of the attributes we assessed provided unequivocal criteria for distinguishing between SJKF dens and CAGS burrows. Also, SJKF occasionally usurp CAGS burrows and CAGS occasionally move into vacant SJKF dens. Therefore, administering lethal control measures within burrows should be avoided as it presents too great a risk to SJKF as well as the many other species that also use CAGS burrows.

Observations of Gray Fox Urocyon cinereoargenteus (Schreber, 1775) (Mammalia: Carnivora: Canidae) denning behavior in New Hampshire, USA

Dens are important for mammals because they provide protection for dependent young from weather and predators. Gray Foxes Urocyon cinereoargenteus are an understudied mesocarnivore that range across North and Central America, and have limited information available on demographics and denning behaviors. We monitored a Gray Fox den in New Hampshire over the course of three years (2017–2020) to quantify behaviors and document visitation and activity patterns of Gray Foxes and other mammal species. We observed Gray Fox pairs intensively using the den during parts of the first and second years of the study. Across the 949 trap nights over which we monitored the den, use by adult Gray Foxes peaked in spring – coinciding with the pup-rearing season. During this time, the adults were diurnal with peaks in the afternoon, opposed to being crepuscular at other times of the year. We did not observe any puppies during the first breeding season, but during the second year we documented a puppy emerging from the den on 24 May 2018. All excursions by the puppy outside the den for the first five days were restricted to the immediate area near the den entrance and the puppy was always with an adult when outside the den. During the puppy’s second solo excursion, however, we documented a Bobcat Lynx rufus pounce and kill the puppy, after which the adults abandoned the den. We also observed the common (squirrels and rabbits) and uncommon (a bat) prey items brought to the den, and the den being shared among multiple species. Our observations highlight the importance of dens for protecting young, and our observations of visitation and activity patterns, as well as common and uncommon prey, help inform our understanding of the denning behavior of Gray Foxes.

Burrow Excavation by an Eastern Spotted Skunk and Visitation by a Long-Tailed Weasel

In this field note, we detail video evidence of Spilogale putorius (Eastern Spotted Skunk) further excavating a den site that was subsequently visited by Mustela frenata (Long-tailed Weasel). In October 2019 in Burke County, NC, we tracked a radio-collared Eastern Spotted Skunk to a small ground burrow. A camera trap was set outside the den entrance for 7 days. During this period, we observed that the burrow was occupied by 1 or more individual spotted skunks, and concurrently occupied by 2 spotted skunks on at least 1 occasion. The burrow was further excavated by 1 of the spotted skunks, representing the first recorded footage of this behavior in the Eastern Spotted Skunk. On 1 occasion, between visits to the den by the spotted skunks, a Long-tailed Weasel investigated the burrow. This observation represents one of the first close associations between these cryptic species.

Ecological plasticity of denning chronology by American black bears and brown bears

Ecological plasticity may index the capacity of individuals, populations, and species to respond to stochasticity. Few studies have demonstrated mechanisms influencing expression of plasticity and less have addressed proximate and causal mechanisms at multiple scales. We used linear models and meta-analyses to investigate factors influencing among and within population plasticity in den chronology for American black bears (Ursus americanus) and brown bears (U. arctos) in North America. We found later mean den entrance date and longer mean duration of denning among populations for both species in response to apparent increasing food availability during the growing season and denning period, along with later onset and shorter duration of mean snow accumulations ≥10 cm. Greater variability in den chronology appeared to be in response to greater variability in snow accumulation and duration precluding access to forage. Observed patterns of plasticity in den chronology varied among age-reproductive groups with male bears denning later and for shorter duration than sub-adults, non-parturient females, and parturient females. This pattern supports expected allometric energetic demands and energetic expenditures required for reproduction. Furthermore, our results align with previously published works indicating that plasticity in den chronology in response to relaxed selective pressure of food availability is energetically advantageous under the cost-benefit hypothesis of energy conservation. Understanding how species respond to variation in selective pressures is central to predicting these effects and our understanding of evolutionary and ecological processes.

American black bear den-site selection and characteristics in an urban environment

Selection of den sites is a crucial aspect of American black bear (Ursus americanus) life history. High-quality dens provide thermal insulation, protection from disturbance, suitable environment for parturition and cub development, and proximity to available forage upon emergence. Black bears are increasingly coexisting with people in human-dominated landscapes; however, little is known about whether urban environments influence characteristics of dens and den site selection. Our objective was to determine the effect of housing density (a proxy for human activity and availability of anthropogenic resources) on selection of den sites in years of good and poor natural forage. We additionally compared size, shape, and location of dens of males and females to describe den characteristics and explore whether differences existed between males and females. We revisited 34 den locations detected during a 6-year (2005–2010) urban black bear study in Aspen, Colorado, USA, and measured den entrance and den volume. We fit a conditional logistic regression model using a resource selection function framework to determine the importance of housing density and other landscape variables (elevation, slope, aspect, and vegetation type) associated with den site selection. Slope was the best predictor of den site selection and there was no relationship between den selection and housing density, indicating that black bears were neither avoiding nor seeking urban areas for denning. Dens were smaller for females ( = 3.30 m3, SE = 1.94, n = 22) than for males ( = 7.56 m3, SE = 3.31, n = 8), supporting the idea that females have greater constraints in den characteristics, possibly related to cub development and security from predation or because females generally are smaller than males.

Sex-specific variation in denning by brown bears

Denning characteristics of brown bears (Ursus arctos) have been described in numerous studies; however, population specific factors (i.e., landscape characteristics and climate) can greatly influence the location and timing of denning. Our objective was to evaluate den-site characteristics and denning chronology for male and female brown bears in Lake Clark National Park and Preserve, Alaska. We used maximum entropy modeling to characterize attributes of den sites and generalized linear mixed models to compare denning chronology between males and females. We located 70 den sites (19 male and 51 female) and documented den entrance (n = 61 [15 male and 46 female]) and emergence (n = 60 [13 male and 47 female]) dates for bears from fall 2014 to spring 2017. The best performing model for estimating probable male den-site use (AUC = 0.862) was most influenced by slope (79.5%). The most parsimonious female model (AUC = 0.910) included elevation (49.3%), slope (43.1%), and aspect (7.6%). Female brown bears on average denned at higher elevations (868, SE = 190 m) than males (762, SE = 195 m) (F1,73 = 4.08, P = 0.047). Additionally, female bears entered dens 8 days earlier than males (SE = 12.82; 20 and 28 October, respectively, P = 0.04), and although not significant (P = 0.09), average female den emergence dates were 7 days (SE = 15.14) later than males. With the potential for increased human activities (i.e. resource extraction and associated access), gaining an understanding of population specific denning requirements is essential for developing future management actions. Our results provide valuable information that will allow decision makers to structure future development in a way that avoids habitats important for denning, and allows for reduced disturbance of winter den sites.

Distribution Pattern of Red Fox (Vulpes vulpes) Dens and Spatial Relationships with Sea Turtle Nests, Recreation, and Environmental Characteristics

Although sea turtles are formidable prey as adults, their nests are highly vulnerable to terrestrial predation. Along the Southeastern coast of the United States, a primary predator of sea turtle nests is the red fox (Vulpes vulpes). Examining the relationship between fox populations and nest predation is often difficult due to coastal development. Masonboro Island, North Carolina is an undeveloped, natural, 13-km-long barrier island complex that is a component of the North Carolina National Estuarine Research Reserve (NERR). Masonboro Island consists of beaches, a dune ridge, back barrier flats, an expansive salt marsh, a lagoon, and spoil islands seaward of the Intracoastal Waterway. A field survey, which was conducted each spring from 2009 through 2012, recorded den entrance coordinates based upon recent use by foxes. Sea turtle nests were located using a similar survey methodology, which identifies viable and predated nests as well as false crawls. A series of spatial-temporal pattern analysis techniques were used to identify trends through time. The results indicated that: (1) fox den entrances and predated sea turtle nests were clustered throughout the island (p = 0.01); (2) den entrances in the northern part of the island were closer to the sea turtle nests than other locations on the island; (3) fox den entrances were positively correlated (p = 0.01) with dune height, (4) fox den entrances were located closer to the island boat access sites than expected (p = 0.01). A variety of spatial sensitivity tests were used to test the validity of the statistically significant cluster analyses. A Geographically Weighted Regression model was created to predict the location of fox dens using dune elevation, the distance to predated sea turtle nests, and the distance to boat access sites. The model accounted for 40% of the variance and had a small residual error, which indicates that the independent variables were statistically valid. Results from this project will be used by the NC NERR staff to develop management plans and to further study fox-related impacts on the island. For example, given the higher density of fox den entrances on the northern part of the island, managers may consider targeted wildlife control measures during the sea turtle nesting season to diminish predation.

Characteristics of a naturally regulated grizzly bear population

ABSTRACTKnowledge of density‐dependent responses in grizzly bears is largely circumstantial yet critical to managing populations near carrying capacity. We studied grizzly bear (Ursus arctos) body condition and demographics in Denali National Park, Alaska, USA, 1991–1998, and compared our results with data from a nearby heavily hunted population to better understand the characteristics of a naturally regulated bear population. We captured grizzly bears just after den emergence in spring (May) and just before den entrance in fall (Sep). We measured body fat using bioelectrical impedance analysis, estimated bear ages, and fitted adult, subadult, and 2‐year‐old dependent bears with telemetry‐collars. We used capture‐mark‐resight techniques to estimate density. We estimated grizzly bear density at 37 bears/1,000 km2; density of adult and subadult bears was 27 bears/1,000 km2. Adult females that produced cubs had 40% more fat and 10% more lean mass pre‐denning than non‐reproductive females but had similar lean mass and similar but very low body fat (8%) post‐denning. Adult females that produced cubs lost more fat and lean mass over winter than non‐reproductive adult females. The physiological demand on adult females producing cubs was 29 kg of total body mass split evenly between fat mass and lean mass. Females that did not lose cubs during the cubs’ first summer averaged more body fat the previous fall than those that lost partial or entire litters. Reproductive rate (0.34) and average litter size (2.1) were high and comparable to increasing populations (λ > 0). Age of dependent young at family breakup (2.9 yr) and age of first reproduction (7.5 yr) were high and comparable to declining populations (λ < 0). Cub (0.34), cub litter (0.43), and yearling survival rates (0.46) were low. Subadult and adult survival rates were high (0.94–1.00) for both sexes. The female age structure was bimodal, suggesting episodic recruitment. The percentage of subadult males was low (3% of population and 10% of male segment). We conclude that the grizzly bear population in Denali National Park was near or at carrying capacity relative to available nutritional resources, adult female access to nutritional resources determined whether cubs were born and the likelihood of their survival, and high dependent bear mortality was the primary factor limiting recruitment and regulating the population. © 2018 The Wildlife Society.

Interesting records of two small carrion beetles (Coleoptera: Leiodidae: Cholevinae) from Hungary

Cholevinus pallidus rufus (Kraatz, 1870), found in a red fox den entrance is reported for the first time from Hungary. Choleva (Choleva) lederiana pilisensis Růžicka et Vavra, 2003, an endemic subspecies from Hungary, is reported from additional localities in Pilis Mts and Buda Hills. With 5 figures.

From brooding to hatching: new insights from a female Octopus vulgaris in the wild

A brooding Octopus vulgaris female was monitored for 128 days in her natural habitat. The main reproductive events and embryonic development in relation to the temperature inside the spawning den, which was recorded by long-battery-life mini-data loggers, are described in the wild. The den temperature ranged from 12.9 to 19.3°C. The total number of egg strings was 160, and the total number of eggs spawned ranged between 139,040 and 241,760 (mean 190,400). The brooding period, the egg laying interval and the duration of the hatching course lasted 128, 35 and 43 days, respectively. Both egg laying and hatching were intermittent processes. The time taken for embryonic development was variable (85–128 d) and depended on the laying date, temperature and position of the string in the egg cluster and the position of the egg in the egg string. The first hatching observed occurred after a progressive and gradual increase of the temperature from 14.9 to 19.3°C. The 280 min of video recordings taken by scuba divers showed that several times, this female opened and closed a small window in the obstructions of the den entrance to facilitate a way out for the hatchling batches.

Behavioural observations of the common octopus Octopus vulgaris in Baía dos Tigres, southern Angola

Observations on the behaviour of the common octopus Octopus vulgaris were made during daytime and night-time sampling on an unexploited rocky reef habitat in Baía dos Tigres, southern Angola. The relative numerical abundance sampled was 0.47 octopus person–1 h–1 during the day and 5.33 octopus person–1 h–1 during the night, suggesting that the population under study was nocturnal. The activity patterns differed between sizes of octopus. Small octopus (<20 cm total length [TL]) were observed roaming during the night, whereas the large individuals (>20 cm TL) generally fed in their dens. This ontogenetic behavioural shift may be due to tidal constraints or could be a strategy to avoid cannibalism. Octopus inhabiting a shallow, small-boulder substratum made extensive modifications to their habitat, excavating dens of up to 1 m deep in the sand below the boulders. These dens were not visible during the day as the octopus appeared to retract the small boulders over their den entrances. This unique behavioural strategy is thought to be a means to reduce predation and reduce light intensity during the day. Octopus were not observed in the small-boulder habitat during the five hours of daytime sampling. With nocturnal activity and extensive habitat modification, it is likely that avoidance of predation may be an important driver influencing the behaviour of the octopus population under study.

Denning Chronology of Black Bears in Eastern Rocky Mountain National Park, Colorado

ABSTRACT. Understanding factors influencing the timing of den entrance and emergence of black bears (Ursus americanus) provides insight for bear management. We determined den entrance and emergence dates for bears in Rocky Mountain National Park (RMNP) and related these dates to vegetative productivity, weather, habitat, and demographic factors to assess the influence of these factors on denning chronology. Date of den entrance was most strongly influenced by age class, precipitation, and proportion of human-use areas in annual home ranges. Den entrance was typically later for adult bears during wetter years and when annual home ranges contained a greater proportion of human-use areas. Sex and presence of human-use areas were most strongly related to den emergence. Male bears typically emerged from dens before females, and bears emerged from dens earlier when human-use areas composed a greater proportion of annual home ranges. Collectively, our results suggest that denning behavior of black bears in RMNP ...

Octopus sucker-arm coordination in grasping and manipulation*

In natural settings octopuses use their arms and suckers in a variety of dexterous manipulation tasks, such as extracting prey from crevices and burrows, opening bivalve shells, and arranging middens in front of den entrances. Octopuses use multiple suckers on a single surface for a power grasp that supports their locomotion or permits the animal to carry or move small objects. Similar to squids engaged in prey capture, octopuses can project an arm from their body, attach a group of distal suckers, and pull an object toward themselves by shortening the arm. I investigated octopuses' use of suckers in similar tasks under controlled, reproducible laboratory conditions. Because larger suckers can generate larger adhesion forces, I hypothesized that the larger suckers toward the base of the arm would be preferred in tasks requiring the arm to employ greater forces. Octopuses did not use the strategy found in squid tentacles: applying suckers of appropriate force generation to a surface and lifting or pulling ...

The characteristics of squirrel glider (Petaurus norfolcensis) den trees in subtropical Australia

Effective management of tree-hollow-dependent wildlife requires a sound knowledge of the characteristics of the trees used for shelter or breeding. We used radio-tracking to identify the den trees of squirrel gliders (Petaurus norfolcensis) in south-east Queensland (Qld) and north-east New South Wales (NSW). Squirrel gliders used dead trees as well as 13 species of living tree for dens across the two locations. Dead trees accounted for a large percentage of dens (54% of 48 dens in Qld, and 50% of 18 dens in NSW) despite comprising only 3–10% of the forest (trees &gt;20 cm diameter at breast height (dbh)) at each location. This preference is largely due to dead trees being more likely to contain hollows, accounting for 26–44% of available hollow-bearing trees. Mean den tree size (dbh) was 48.9 ± 2.4 cm in Qld and 62.8 ± 5.6 cm in NSW. Den entrance height averaged 6.8 ± 1.2 m in Qld and 11.9 ± 1.3 m in NSW. Fissures in the trunk and holes in branches were the most common of six hollow types used. At one location branch end hollows were ignored relative to their availability. Den entrances varied in size (2.5–12 cm wide) but most were ≤5 cm in diameter. Entrance size of hollows appears to be the hollow attribute of most importance to squirrel gliders. Monitoring of these den trees over several years revealed the collapse of three dead den trees at each location, which is equivalent to an annual loss of 3% of den trees. Further research is needed to determine whether this will lead to a future shortage of den trees.

Costs and strategies of communal den use vary by rank for spotted hyaenas, Crocuta crocuta

Spotted hyaenas house cubs in communal dens during much of the early development period. This practice facilitates social integration of young into the clan's dominance hierarchy. For Crocuta, however, use of communal dens entails costs. Within a clan, social rank is correlated with individual privilege. If costs of denning communally likewise vary with rank, then breeding females may be forced to adopt different denning strategies accordingly. I quantified three costs (den access, visitor aggression, disruption to nursing bouts) in relation to maternal rank for 27 females within one clan. I examined denning strategies that may reduce costs (cub age when transferred to a communal den, social correlates of den selection, daily attendance pattern) to determine whether they varied predictably in relation to mother's rank. Although conflicts among mothers were infrequent, low-ranking females were more likely to be denied access to the communal den entrance and, possibly in response, more often attended their cubs when other mothers were absent. High-ranking mothers were visited more often, but treated less aggressively than were mid- or low-ranking mothers. In efforts to socialize with mothers and cubs, visitors often disrupted nursing bouts. Cub responses to nursing disruptions were correlated with cub survival. Mothers showed rank-related differences in den selection; high-ranking females occasionally chose dens with fewer occupants, while all other mothers chose dens containing the highest number of animals. Mid- and low-ranking mothers were attracted to dens containing high-ranking mothers and cubs. The potential benefits of affiliating with high-ranking individuals are discussed.

Multiple Scale Den Site Selection by Swift Foxes, &lt;em&gt;Vulpes velox&lt;/em&gt;, in Southeastern Colorado

Predation by Coyotes (Canis latrans) is a major source of mortality in Swift Fox (Vulpes velox) populations. Year-round den use by Swift Foxes is likely to be a predator avoidance strategy. Due to the importance of denning to Swift Fox ecology, we recorded den site selection of Swift Foxes in southeastern Colorado. Den site selection was recorded at two scales: microhabitat characteristics at the den and den placement within the home range. The number of den entrances, height and width of each entrance, aspect, hill position, slope, percent rock in soil, vegetative cover, and horizontal foliar density of 42 Swift Fox dens were examined during December 1999 – April 2000. This was compared to the same microhabitat characteristics at 42 random sites within Swift Fox home ranges to determine if Swift Foxes were using site characteristics according to their availability. Our results indicated that Swift Foxes were not highly selective of den sites based on the microhabitat characteristics evaluated in this study, although Swift Foxes selected areas of intermediate rock percentages. In addition, Swift Foxes were radio-tracked throughout the sample period and the location and frequency of use of known dens were recorded. Within the core area of home ranges, Swift Foxes used more dens (mean = 3.51 ± 1.70 (SD)), and had a higher frequency of use of dens (mean = 8.20 ± 6.01) than in the mid-range area (number of dens, mean = 0.90 ± 0.94; frequency, mean = 1.27 ± 2.12) and the boundary area (number of dens, mean = 0.34 ± 0.53; frequency, mean = 0.45 ± 0.93) of the home range. We discuss our results in terms of the importance of dens in facilitating escape from Coyotes. These results illustrate the need for examining den site selection at multiple scales to determine all selection factors, and to provide information useful for recovery and management efforts for this species.

Comparación de la conducta de marcaje de la nutria (Lutra lutra L.) en cautividad durante el periodo de gestación y cuidado de las crías y fuera de éste

Comparison of captive otter (Lutra lutra L.) marking behaviour during the gestation and care of cubs periods and out of breeeding season We studied the marking behaviour of captive otter females during different phases of breeding (mating, gestation, cubs inside den and cubs going outside den), and we compared it with that of males and subadults. During the gestation and when cubs were inside den, females practically don’t laid spraints in detectable locations and used a very few latrines. This could be a mechanism to avoid their detection. The mating pairs showed a higher diversity of substrate used and spraint locations, a lower being found in subadults and females with cubs inside the den (laying spraints mostly on land). Females with cubs (both, inside and going outside den) and subadultuds laid more often spraints close to the den entrance. We discuss about the possible influence of this behaviour on the distribution and habitat studies, using such kind of indirect signs.

Polar bear (Ursus maritimus) maternity denning habitat in western Hudson Bay: a bottom-up approach to resource selection functions

We examined habitat characteristics of 101 polar bear (Ursus maritimus Phipps, 1774) den sites and 83 adjacent unoccupied sites in western Hudson Bay, Canada, between mid-August and early October 2001 and 2002. Bears denned almost exclusively in peat banks (n = 100) along the edges of creeks, rivers, and lakes adjacent to open lichen tundra sites. Den sites differed from unoccupied sites by having greater tree cover (P = 0.002), less moss cover (P &lt; 0.001), and less herbaceous cover (P = 0.005). The presence of tree roots improved substrate stability, providing support to den structures. Den entrance azimuths were weighted toward a southeasterly aspect (P &lt; 0.005), away from the prevailing northwest winds. To identify habitats with the greatest relative probability of having a den, a resource selection function (RSF) model was developed using remote sensing imagery and 1245 known den locations. High normalized difference vegetation index and brightness values derived from Landsat imagery, which were in close proximity to water, corresponded well with polar bear den sites. Identification of critical denning areas through the use of RSF will provide resource managers with a valuable tool for ensuring the protection of denning habitat, and consequently female bears and their young.

Winter ecology of American black bears in a desert montane island

Abstract American black bears (Ursus americanus) have recolonized western Texas following extirpation in the mid-1900s. Knowledge of winter ecology of black bears is important for conservation and management because denning, parturition, and early cub development occur during this period. We monitored 13 radiocollared black bears for 22 den-years in Big Bend National Park (BBNP) during 1998–2003. All pregnant females (n=6), 2 females with yearlings, 7 subadults, and 1 adult male denned. Three females with yearlings remained active during winter 1998–1999. We located 4 cave dens, 5 ground dens, and 6 rock-pile dens. Volume and elevation of den sites averaged 2.00 m3 (SD=1.51) and 1,800 m (SD=346), respectively. Mean (±SD) dates of den entrance and emergence for 5 pregnant females were 30 December±17 days and 27 April±21 days, respectively, producing a mean denning period of 118±29 days. Pregnant females exited dens later (P= 0.003) and denned longer (P=0.02) than solitary females and males. Black bears in ...

Characteristics of current and historical kit fox (Vulpes macrotis) dens in the Great Basin Desert

We examined the ecological and physical characteristics of den sites for 13 adult kit fox (Vulpes macrotis) in western Utah from December 1998 to February 2001. We also compared current and historical den distribution among habitat types. The number of den sites used was not influenced by home-range size (P = 0.11) or season (P = 0.40), but was influenced by geographical area. Home-range size was smallest (P = 0.007) and the number of dens used was greatest (P = 0.009) in mountainous areas. Ecological and physical characteristics of single-use dens (n = 30) were compared with those of multiple-use (n = 53) and natal dens (n = 8). Characteristics that differed between den types included number of entrances (P = 0.0001), diameter of entrances (P = 0.003), and height of vegetation along transects (P = 0.0001). Natal den entrance azimuths were weighted towards a northwesterly aspect (P = 0.0022); however, single- and multiple-use den exits appeared to be randomly distributed. Historical changes in kit fox den site selection have occurred since 1959 (P &lt; 0.0001). We characterized more dens in invasive grasslands and fewer in greasewood (Sarcobatus vermiculatus) habitats than previously described. The conversion of native habitat to grassland and the increase in coyote population may have altered kit fox distribution to include mountainous areas not previously described.