Ecological theory predicts that the diffuse risk cues generated by wide-ranging, active predators should induce prey behavioural responses but not major, population- or community-level consequences. We evaluated the non-consumptive effects (NCEs) of an active predator, the grey wolf (Canis lupus), by simultaneously tracking wolves and the behaviour, body fat, and pregnancy of elk (Cervus elaphus), their primary prey in the Greater Yellowstone Ecosystem. When wolves approached within 1 km, elk increased their rates of movement, displacement and vigilance. Even in high-risk areas, however, these encounters occurred only once every 9 days. Ultimately, despite 20-fold variation in the frequency of encounters between wolves and individual elk, the risk of predation was not associated with elk body fat or pregnancy. Our findings suggest that the ecological consequences of actively hunting large carnivores, such as the wolf, are more likely transmitted by consumptive effects on prey survival than NCEs on prey behaviour.

Conservation of migration requires information on behavior and environmental determinants. The spatial distribution of forage resources, which migration exploits, often are altered and may have subtle, unintended consequences. Supplemental feeding is a common management practice, particularly for ungulates in North America and Europe, and carryover effects on behavior of this anthropogenic manipulation of forage are expected in theory, but have received limited empirical evaluation, particularly regarding effects on migration. We used global positioning system (GPS) data to evaluate the influence of winter feeding on migration behavior of 219 adult female elk (Cervus elaphus) from 18 fed ranges and 4 unfed ranges in western Wyoming. Principal component analysis revealed that the migratory behavior of fed and unfed elk differed in distance migrated, and the timing of arrival to, duration on, and departure from summer range. Fed elk migrated 19.2 km less, spent 11 more days on stopover sites, arrived to summer range 5 days later, resided on summer range 26 fewer days, and departed in the autumn 10 days earlier than unfed elk. Time-to-event models indicated that differences in migratory behavior between fed and unfed elk were caused by altered sensitivity to the environmental drivers of migration. In spring, unfed elk migrated following plant green-up closely, whereas fed elk departed the feedground but lingered on transitional range, thereby delaying their arrival to summer range. In autumn, fed elk were more responsive to low temperatures and precipitation events, causing earlier departure from summer range than unfed elk. Overall, supplemental feeding disconnected migration by fed elk from spring green-up and decreased time spent on summer range, thereby reducing access to quality forage. Our findings suggest that ungulate migration can be substantially altered by changes to the spatial distribution of resources, including those of anthropogenic origin, and that management practices applied in one season may have unintended behavioral consequences in subsequent seasons.

Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, on shore. Although the physiology of "ice" bears in summer is unknown, "shore" bears purportedly minimize energy losses by entering a hibernation-like state when deprived of food. Such a strategy could partially compensate for the loss of on-ice foraging opportunities caused by climate change. However, here we report gradual, moderate declines in activity and body temperature of both shore and ice bears in summer, resembling energy expenditures typical of fasting, nonhibernating mammals. Also, we found that to avoid unsustainable heat loss while swimming, bears employed unusual heterothermy of the body core. Thus, although well adapted to seasonal ice melt, polar bears appear susceptible to deleterious declines in body condition during the lengthening period of summer food deprivation.

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Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio‐tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences for energy demands of adult females in the Beaufort and Chukchi seas during two periods with different sea ice characteristics. Westward and northward drift of the sea ice used by polar bears in both regions increased between 1987–1998 and 1999–2013. To remain within their home ranges, polar bears responded to the higher westward ice drift with greater eastward movements, while their movements north in the spring and south in fall were frequently aided by ice motion. To compensate for more rapid westward ice drift in recent years, polar bears covered greater daily distances either by increasing their time spent active (7.6%–9.6%) or by increasing their travel speed (8.5%–8.9%). This increased their calculated annual energy expenditure by 1.8%–3.6% (depending on region and reproductive status), a cost that could be met by capturing an additional 1–3 seals/year. Polar bears selected similar habitats in both periods, indicating that faster drift did not alter habitat preferences. Compounding reduced foraging opportunities that result from habitat loss; changes in ice drift, and associated activity increases, likely exacerbate the physiological stress experienced by polar bears in a warming Arctic.

Migratory ungulates are often exposed to anthropogenic infrastructure along their migration routes. Understanding the influence of such development on migratory behavior is critical to successful planning and conservation. Impermeable barriers have obvious and detrimental effects to migratory ungulate populations, but the influence of semi‐permeable barriers, where the connectivity of migration habitat is maintained but the migration routes are compromised by anthropogenic development, remains unclear. We evaluated the influence of development on the migratory behavior of individual mule deer (Odocoileus hemionus) in western Wyoming, USA. We used fine‐scale movement data to evaluate the influence of anthropogenic infrastructure on deer movement rates, stopover use, and fidelity to migration routes for individual animals across multiple seasons and years. Deer avoided human infrastructure when selecting stopover sites. Fidelity to migration routes and stopover areas, as measured by the degree of spatial overlap between years, was not influenced by development, except in one heavily developed area. Our results suggested that deer increased rate of movement, reduced time in stopovers, and shifted stopovers in areas of intense development. In most cases, deer maintained fidelity to migration routes, regardless of development, suggesting that deer mediated exposure to development by altering movement—rates and timing—rather than the routes they traversed. This work adds to a growing number of studies indicating that development can disrupt migratory behavior. Understanding how different types and intensities of development influence migration can help inform land‐use planning and conservation of migratory ungulates.

Murine models have become essential tools for understanding the complex interactions between gut microbes, their hosts, and disease. While many intra-facility factors are known to influence the structure of mouse microbiomes, the contribution of inter-facility variation to mouse microbiome composition, especially in the context of disease, remains under-investigated. We replicated microbiome experiments using identical mouse lines housed in two separate animal facilities and report drastic differences in composition of microbiomes based upon animal facility of origin. We observed facility-specific microbiome signatures in the context of a disease model [the Ednrb (endothelin receptor type B) Hirschsprung disease mouse] and in normal C57BL/6J mice. Importantly, these facility differences were independent of cage, sex, or sequencing-related influence. In addition, we investigated the reproducibility of microbiome dysbiosis previously associated with Ednrb-/- (knock-out; KO) mice. While we observed genotype-based differences in composition between wild-type (WT) and KO mice, these differences were inconsistent with the previously reported conclusions. Furthermore, the genotype-based differences were not identical across animal facilities. Despite this, through differential abundance testing, we identified several conserved candidate taxa and candidate operational taxonomic units that may play a role in disease promotion or protection. Overall, our findings raise the possibility that previously reported microbiome-disease associations from murine studies conducted in a single facility may be heavily influenced by facility-specific effects. More generally, these results provide a strong rationale for replication of mouse microbiome studies at multiple facilities, and for the meticulous collection of metadata that will allow the confounding effects of facility to be more specifically identified.

The isotopic niche of consumers represents biologically relevant information on resource and habitat use. Several tools have been developed to quantify niche size and overlap. Nonetheless, methods adapted by spatial ecologists to quantify animal home ranges can be modified for use in stable isotope ecology when data are not normally distributed in bivariate space. We offer a tool that draws on existing spatial metrics, such as minimum convex polygon (MCP) and standard ellipse area (SEA), and add novel metrics using kernel utilization density (KUD) estimators to measure isotopic niche size and overlap. We present examples using empirical and simulated data to demonstrate the performance of the package kernel isotopic niches in r (rKIN) under various scenarios. Results of niche size from MCP, SEA and KUD were highly correlated but divergent among datasets. Overall, the KUD method produced the largest niche sizes and was more sensitive to the distribution of the isotopic data. Pairwise estimates of overlap were highly variable, likely because MCP and SEA inherently include or exclude unused areas in the resulting niche estimate. Four bandwidth methods (reference, normal scale, plug‐in and biased cross‐validation) produced comparable estimates of niche size and overlap at various sample sizes (10–40). Niche size and overlap were consistent across sample sizes >15. Use of rKIN will allow isotope ecologists to quantify niche shifts, expansions or contractions, as well as assess the performance of several estimation methods. The package also can be applied to other data types (e.g. principal component analysis, multi‐dimensional scaling) so long as axes and measurement units are identical and can be converted to Cartesian coordinates.