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When wildlife species exhibit unexpected associations with vegetation, replication of studies in different locales can illuminate whether patterns of use are consistent or divergent. Our objective was to describe fine‐scale forest conditions used by Pacific martens (Martes caurina) at 2 study sites in northern California that differed in forest composition and past timber harvest. We identified denning and resting locations of radio‐marked martens and sampled structure‐ and plot‐level vegetation using standardized forest inventory methods between 2009–2021. Woody structures used by martens were significantly larger than randomly available structures across types (e.g., live tree, snag, log) and at both study sites. Den and rest structures occurred in areas characterized by higher numbers of logs and snags, lower numbers of live trees and stumps, larger diameter live trees and logs, and greater variation in live tree and log diameter. Features of denning and resting locations were largely consistent across study sites and were generally representative of fine‐scale forest heterogeneity and increased structural complexity, conditions that martens have been widely associated with at broader spatial scales (i.e., home range or landscape). The spatial occurrence of denning and resting locations may indicate that fine‐scale structural complexity facilitates marten foraging while reducing predation risk. Our work offers timely and directed information that can guide forest management in the context of increased landscape change. [ABSTRACT FROM AUTHOR]

Oil and gas activities on Alaska's North Slope overlap spatially with polar bear (Ursus maritimus) maternal denning habitat and temporally with the peri‐partum and emergence periods. Noise associated with these activities can be substantial and concerns regarding the effects on polar bears have been acknowledged. But the secluded and ephemeral nature of subnivean maternal dens renders the measurement of behavioral and physiological responses of bears to noise exposure challenging, except for rare cases when disturbance‐prompted den abandonment has been documented. These limitations, coupled with the uncertainty associated with the synergistic effects of anthropogenic activities on bears in a rapidly changing Arctic, prompt the need to develop predictive models of disturbance to ensure management guidelines effectively mitigate disturbance. Towards this end, we characterized noise propagation from 9 sources (2 aircraft, 2 over‐tundra tracked vehicles, 4 wheeled on‐road vehicles, and humans walking) used to support industrial activities around artificial snow dens near Milne Point, Alaska, USA, in March–April 2010. We built dens in 4 configurations to mimic variability in den roof thickness and to evaluate differences in noise propagation from when the den was closed compared to being open, similar to den emergence. We integrated these data with an existing polar bear audiogram and developed models to predict auditory‐detection probabilities as a function of distance from the den. Within a closed den, aircraft had high probabilities (detection probability ≥75%) of being detected by polar bears at distances ≤1.6 km and ground‐based sources had high probabilities of detection at distances ≤0.8 km. On average, closed dens reduced noise levels by 15 decibels (dB) relative to open dens. Our findings indicate that although polar bear snow dens effectively attenuate acoustic sound pressure levels, noise from some industrial support vehicles was likely to be detected farther from dens than previously documented. These results reinforce the importance of maintaining buffer zones around polar bear dens to minimize the potential for den disturbance. © 2020 The Wildlife Society. We report a relatively high (≥0.75) probability that polar bears in dens can hear industrial support vehicles (especially aircraft) from ≤1.6 km away. Our findings support the use of 1.6‐km exclusion zones around known polar bear den sites in Alaska, USA. [ABSTRACT FROM AUTHOR]

The eastern spotted skunk (Spilogale putorius) is a species of conservation concern in much of its range and has experienced a decline since the early to mid‐1990s. But the subspecies that inhabits peninsular Florida, the Florida spotted skunk (S. p. ambarvalis), might still be abundant and is an important nest predator of the endangered Florida grasshopper sparrow (Ammodramus savannarum floridanus). To gain insight on this little‐studied subspecies and inform potential management strategies, we conducted a resource selection study on the Florida spotted skunk. We examined 5 hypotheses for den site selection related to den type, vegetation, and landscape characteristics in a dry prairie ecosystem in central Florida. We tracked 36 individual skunks to 757 den sites. Using discrete choice analysis, we found that male and nonbreeding female skunks at our study site were 5 times more likely to select a mammal burrow over a gopher tortoise (Gopherus polyphemus) burrow, that selection of a den site increased 34% for each 1‐burrow increase in the number of nearby burrows, and that selection of a den site increased 3% for every 10‐cm increase in a visual obstruction index. Similarly, breeding female skunks were more likely to select mammal burrows and shallow depressions over gopher tortoise burrows by 16‐fold and 13‐fold, respectively, and selection of a den site increased by 75% for every 1‐burrow increase in the number of nearby burrows. In contrast to previous studies that occurred in forested, mountainous environments elsewhere in the species' range, our findings suggest that den characteristics might be more important than landscape or vegetation characteristics to Florida spotted skunk den site selection in dry prairie. Additionally, the frequency of prescribed fires on the landscape did not appear to affect Florida spotted skunk den site selection. Thus, Florida spotted skunks in this ecosystem might be landscape generalists, thereby potentially limiting the ability of managers to control nest predation by this subspecies through habitat management. © 2019 The Wildlife Society. In 2016 and 2017 we conducted a study on the Florida spotted skunk and examined support for the hypothesized influence of den type, vegetation, and landscape characteristics on den site selection. Our study suggests that although den type, the number of available nearby burrows, and the amount of vegetative cover at a site were positively related to spotted skunk den site selection, Florida spotted skunks at our site might be generalists, limiting the effectiveness of habitat management practices for this subspecies' benefit or detriment. [ABSTRACT FROM AUTHOR]

Increasing demand for backcountry recreation opportunities during winter (e.g., snowshoeing, helicopter-assisted skiing, snowmobiling) in steep, high-elevation terrain has elevated concern about disturbance to brown bears (Ursus arctos) denning on the Kenai Peninsula, Alaska, USA. To help identify areas where such conflicts might occur, we developed a spatially explicit model to predict potential den habitat. The model indicated brown bears selected locations for den sites with steep slopes, away from roads and trails. Den sites were associated with habitat high in elevation and away from potential human contact. We then compared areas with the highest probability of providing den habitat with patterns of snowmobile and nonmotorized recreation on a portion of the Kenai Peninsula. We found limited overlap between the 2 recreation activities and potential den habitat for brown bears. At the landscape scale, however, backcountry skiing overlapped more high-quality den habitat than did snowmobile riding. Our results may be used by land management agencies to identify potential conflict sites and to minimize the potential effects of recreation activities on brown bears in dens. [ABSTRACT FROM AUTHOR]

Establishing whether conditions are suitable for reproduction would help determine if immigration is necessary for Canada lynx (Lynx canadensis) to persist at the southern edge of the species range. We located den sites and monitored reproduction of radiocollared lynx in Minnesota from 2004 to 2006. Movement rates of denning females measured with Global Positioning System collars were similar to movement rates of lynx elsewhere. Female lynx with kittens used different habitat types in predenning, denning, and postdenning periods. Landscape composition at the scale of the foraging radius around a den site contained more lowland conifer, upland conifer, and regenerating forest than did home ranges or the area used by radio-collared lynx in Minnesota, USA. We used the spatial distribution of cover-type composition around known den sites to predict and map potential denning habitat in northeastern Minnesota. Techniques for identifying the spatial distribution of suitable denning habitat provide a biological basis for management actions that could enhance recovery of Canada lynx populations in the southern part of the species range. [ABSTRACT FROM AUTHOR]

Reports on the effectiveness of using late fall hunting seasons to reduce the proportion of female black bears (Ursus americanus) in the harvest are limited, and the geographic scale over which the technique functions as intended has not been examined. During 1992-2000, we radio-equipped black bears in New Mexico, USA, obtained estimates of 175 den entry and 137 den emergence dates, and used New Mexico Department of Game and Fish harvest data (1985-2000) to test for differences in proportion of females in the harvest relative to denning chronology. Bears in northern New Mexico entered dens earlier and emerged later than bears in southern New Mexico (P ≤ 0.001). In northern New Mexico bears displayed the typical pattern of earlier entry and later emergence by reproductive females, proportion of females in the harvest varied over time as expected, and late fall seasons were effective (P ≤ 0.10). In contrast, denning chronology did not differ by sex in southern New Mexico, proportion of females in the harvest did not change over time, and late fall seasons were not effective (P ≥ 0.18). Manipulation of hunting season dates to influence female mortality can be an effective tool, however our study provides an example of an area where denning chronology did not differ by sex and late seasons were not effective. We also observed regional differences in timing of entrance and emergence, which suggest that scale of application may be key. In management jurisdictions that encompass ecologically distinct areas, cover a wide range of latitudes, or are mountainous, successful use of the technique may depend on knowledge of denning chronology at multiple locations and appropriate designation of hunting unit boundaries, season dates, and data analysis units. [ABSTRACT FROM AUTHOR]