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Small mammals in habitats with strong seasonal variation in the thermal environment often exhibit physiological and behavioral adaptations for coping with thermal extremes and reducing thermoregulatory costs. Burrows are especially important for providing thermal refuge when above-ground temperatures require high regulatory costs (e.g., water or energy) or exceed the physiological tolerances of an organism. Our objective was to explore the role of burrows as thermal refuges for a small endotherm, the pygmy rabbit (Brachylagus idahoensis), during the summer and winter by quantifying energetic costs associated with resting above and below ground. We used indirect calorimetry to determine the relationship between energy expenditure and ambient temperature over a range of temperatures that pygmy rabbits experience in their natural habitat. We also measured the temperature of above- and below-ground rest sites used by pygmy rabbits in eastern Idaho, USA, during summer and winter and estimated the seasonal thermoregulatory costs of resting in the two microsites. Although pygmy rabbits demonstrated seasonal physiological acclimatization, the burrow was an important thermal refuge, especially in winter. Thermoregulatory costs were lower inside the burrow than in above-ground rest sites for more than 50% of the winter season. In contrast, thermal heterogeneity provided by above-ground rest sites during summer reduced the role of burrows as a thermal refuge during all but the hottest periods of the afternoon. Our findings contribute to an understanding of the ecology of small mammals in seasonal environments and demonstrate the importance of burrows as thermal refuge for pygmy rabbits.

Patterns of resource selection depend upon an animal's behavioral state. Because management strategies are often crafted from an understanding of animal space use, incorporating behavior explicitly into analyses of resource selection has the potential to improve outcomes. In the Prairie Pothole Region of Manitoba, Canada, raccoons (Procyon lotor) are a nest predator of waterfowl, but it is unclear how raccoons use this landscape during the waterfowl nesting season. Our objective was to use high‐resolution global positioning system (GPS) telemetry to differentiate among behaviors by raccoons and evaluate behavior‐specific habitat selection during the waterfowl nesting season. We collected approximately 32,000 locations from 33 animals during the 2018, 2019, and 2021 nesting seasons, amounting to 632 animal‐night's worth of movement data. We used hidden Markov models (HMM) to fit 4‐state models to the movement trajectories, classified observations into discrete behaviors, and fit behavior‐specific random forest resource selection models to evaluate the relative importance of habitat features on selection. Proximity to a wetland was the most important variable contributing to selection for the resting, foraging, and slow travel states. Probability of use was as high as 95% within or immediately adjacent to a wetland for animals engaged in those behaviors, and our best HMM predicted increasing probability of switching from resting or foraging to directed travel with increasing distance from a wetland edge. Human‐use sites were also important to foraging animals, suggesting raccoons subsidize their diet with anthropogenic food resources during spring and summer. These results illuminate the complexity of habitat selection by a waterfowl predator in this patchy landscape, allowing managers to develop effective conservation strategies (e.g., wetland prioritization and conservation, elimination of anthropogenic subsidies) where raccoons are having a disproportionate effect during the waterfowl nesting season. [ABSTRACT FROM AUTHOR]

Abstract: Contemporary techniques predicting habitat suitability under climate change projections often underestimate availability of thermal refuges. Habitat structure contributes to thermal heterogeneity at a variety of spatial scales, but quantifying microclimates at organism‐relevant resolutions remains a challenge. Landscapes that appear homogeneous at large scales may offer patchily distributed thermal refuges at finer scales. We quantified the relationship between vegetation structure and the thermal environment at a scale relevant to small, terrestrial animals using a new approach for mapping fine‐scale thermal heterogeneity. We expected that vegetation would create attenuated microclimates and that the influence of vegetation structure would vary seasonally. We measured shrub volume, horizontal cover and operative temperature (Te) in a sagebrush‐steppe habitat in Idaho, USA, at 534 microsites across two study sites of c. 1 km2 each. We modelled relationships between habitat structure and both mean daily maximum temperature ( T ¯ max) and mean diurnal temperature range ( DTR ¯) for each study site during summer and winter. Aerial imagery from unmanned aerial systems was used to estimate shrub volume and canopy cover at 1‐m resolution, and we applied the best fit model to map thermal heterogeneity across broader extents. Increasing shrub volume and cover was associated with lower T ¯ max and DTR ¯, but strengths of the relationships differed between study sites. There was considerable heterogeneity in availability of thermal refuges across sagebrush‐steppe rangelands that have traditionally been considered relatively homogeneous. This technique can help ecologists and land managers identify critical thermal refuges that large‐scale climate modelling can overlook and thus contribute to an understanding of animal–habitat relationships under changing climates and land uses. [ABSTRACT FROM AUTHOR]