Search

Reduced food availability is implicated in declines in avian aerial insectivores, but the effect of nutritional stress on mammalian aerial insectivores is unclear. Unlike birds, insectivorous bats provision their young through lactation, which might protect nursing juveniles when prey availability is low but could increase the energetic burden on lactating females. We analyzed a 15‐year capture–mark–recapture data set from 5312 individual little brown myotis (Myotis lucifugus) captured at 11 maternity colonies in northwestern Canada, to test the hypothesis that nutritional stress is impacting these mammalian aerial insectivores. We used long‐bone (forearm [FA]) length as a proxy for relative access to nutrition during development, and body mass as a proxy for access to nutrition prior to capture. Average FA length and body mass both decreased significantly over the study period in adult females and juveniles, suggesting decreased access to nutrition. Effect sizes were very small, similar to those reported for declining body size in avian aerial insectivores. Declines in juvenile body mass were only observed in individuals captured in late summer when they were foraging independently, supporting our hypothesis that lactation provides some protection to nursing young during periods of nutritional stress. Potential drivers of the decline in bat size include one or both of (1) declining insect (prey) abundance, and (2) declining prey availability. Echolocating insectivorous bats cannot forage effectively during rainfall, which is increasing in our study area. The body mass of captured adult females and juveniles in our study was lower, on average, after periods of high rainfall, and higher after warmer‐than‐average periods. Finally, survival models revealed a positive association between FA length and survival, suggesting a fitness consequence to declines in body size. Our study area has not yet been impacted by bat white‐nose syndrome (WNS), but research elsewhere has suggested that fatter bats are more likely to survive infection. We found evidence for WNS‐independent shifts in the body size of little brown myotis, which can inform studies investigating population responses to WNS. More broadly, the cumulative effects of multiple stressors (e.g., disease, nutritional stress, climate change, and other pressures) on mammalian aerial insectivores require urgent attention. [ABSTRACT FROM AUTHOR]

The boreal forest is the largest intact forest in the world, and a refuge for species experiencing range retractions as a consequence of climate and landscape change. Yet, large tracts of the boreal forest are threatened by the cumulative impacts of climate change, natural resource extraction, agriculture, and urbanization, perhaps warranting a shift in focus from biodiversity conservation in intact wilderness to that in anthropologically modified landscapes. We investigated landscape features that influence the distribution of the endangered little brown bat (Myotis lucifugus) in an urbanizing boreal landscape at two spatial scales. We hypothesized that little brown bat activity would be influenced by proximity to available building roosts, because roosts are a potential limiting factor for boreal bats. Secondarily, we predicted that bats would use potential foraging habitat, such as waterbodies, and would avoid young, cluttered forests at the landscape scale. We conducted acoustic surveys of bat activity at 210 sites distributed across the study area in Yukon, Canada, within 1‐km grid cells. We tested a priori hypotheses with a set of candidate regression models, accounting for spatial autocorrelation. Our hypothesis about the relative importance of anthropogenic roosts was not supported. Little brown bats were equally active in urban areas (high building density) and rural areas (low building density), perhaps because roosts were adequately available throughout the region. Instead, habitat use was driven by the distribution of potential foraging habitat, particularly waterbodies, which are important sources of aerial insect prey. Little brown bats also avoided young (≤100‐yr‐old) forest at the landscape scale (including areas regenerating after fire), which may have been poor foraging or roosting habitat, and used areas with a smaller agricultural and industrial footprint. Our results suggest that waterbodies and mature forest are important little brown bat habitats that should be protected from urban encroachment. Proactive conservation of important habitat for species at risk is still possible throughout much of the boreal forest, where human densities are comparatively low and the urban footprint is currently small. [ABSTRACT FROM AUTHOR]

Capture and handling of wildlife is often an important component of studies where detailed demographic, behavioral, physiological, or health data are required. Yet, capturing and handling wildlife is sometimes controversial and lacking public support because of concern about effects on individuals. Investigating potential effects of capturing wildlife is also important to inform data‐censoring protocols when using information obtained from captured animals. We investigated the short‐term effect of helicopter‐based capture and handling on movements of free‐ranging bison (Bison bison) that were chemically immobilized in Yukon, Canada. We examined daily movement rates, home range size, and displacement of global positioning system‐collared individuals immediately after capture and for 20 days thereafter. Our results indicate that there is a minimal short‐term effect of helicopter‐based capture on bison movements. Significant differences from apparent pre‐capture movement behavior were observed only within 24 hours after capture. We observed variation among individuals, however, with some animals taking up to 10 days to return to apparent pre‐capture movement rates, whereas others had no measurable response to capture. Despite individual variation, >80% of individuals had returned to apparent pre‐capture movement behavior within the first 5 days after capture. Furthermore, sex‐based effects were evident: females increased their daily movement rates, home range size, and displacement after capture, whereas males had either no effect or decreased movement rates. Our results suggest that movement rates are altered for only a short period after capture and, therefore, should not have severe negative effects on bison using our protocols. Accordingly, researchers should censor the first 10 days after capture from their analyses to avoid using biased information. Our study should also help inform public discourse regarding capturing and handling wildlife for research or management purposes. © 2019 The Wildlife Society Helicopter‐based capture of global positioning system (GPS)‐collared bison resulted in significant differences from pre‐capture movement behavior only within 24 hours after capture. We observed sex‐based differences in response to being captured and variation among individuals, with some animals taking up to 10 days to return to apparent pre‐capture movement rates. Accordingly, the first 10 days after capture should be censured from analyses to avoid using biased information. [ABSTRACT FROM AUTHOR]