A primary mechanism linking wildlife health to environmental change is the physiological stress response, which plays a critical role in how animals integrate, cope with and respond to environmental change (e.g., landscape transformation, extreme weather). Measures of physiological stress coupled with assessments of behavior, nutritional condition, or indices of an animal’s reproductive state can provide critical information on individual health and fitness and inform our understanding of population dynamics. Conservation physiology has applications for aiding the conservation of imperiled populations, can be applied to evaluate the effectiveness of habitat restoration efforts on targeted wildlife populations, and used to assess multiple management strategies when trying to identify the least impactful management prescription on the health of a target population. The WECOS Lab is actively involved in refining and apply conservation physiology tools to better understand and predict how individuals and populations cope with and adapt to environmental change and to aid the conservation and management of target taxa impacted by human-mediated global change.
Lake Clark National Park and Preserve (LALC) has one of the highest estimated densities of brown bears in the world (~147 individuals/1,000 km2), and provides ample opportunities for visitors to view high numbers of bears with relatively easy access from the largest human population centers of Alaska. This unique situation has made bear viewing the most popular activity for visitors to LALC and has been largely responsible for the significant rise in visitation over the past decade. However, increased human presence in critical brown bear foraging areas can influence bear behavior, including space use, temporal activity patterns, and adversely impact reproduction. Bear behavioral changes may be accompanied by physiological responses that indicate the relative stress levels bears are experiencing. In collaboration with National Park Services personnel, The WECOS Lab is leading efforts to assess human-mediated stress levels in bears. To achieve this goal, we are non-invasively sampling brown bear feces to measure fecal glucocorticoid metabolite concentrations as an index of psychological stress as well as metabolite concentrations of bioactive thyroid hormone (triiodothyronine [T3]) to evaluate potential nutritional stress. We are sampling bears across three sites along the LALC coast: Chinitna Bay, Shelter Creek, Silver Salmon Creek. These three study sites were selected because they support varying levels of human visitation ranging from low to high and a variety of bear viewing methods are employed by visitors, thus providing a means of assessing the relationship between human visitation and short-term stress in brown bears. Results from this work will be used in conjunction with results from a two-year study focused on visitor use and experience project and salt marsh vegetation monitoring to help inform LACL personnel on future coastal management and planning efforts.
BROWN BEAR PHYSIOLOGICAL RESPONSE TO HUMAN VISITATION ON THE LAKE CLARK COAST
NONINVASIVE TOOLS FOR MONITORING PHYSIOLOGICAL STRESS IN WILDLIFE
Analysis of hormone metabolites extracted from feces is a valuable tool for studying the physiology of free-ranging wildlife. Feces collection is efficient and cost-effective relative to other biological matrices (e.g., hair, saliva, blood) and due to the non-invasive nature of fecal sampling, potential disturbance of the target taxa can be minimized and/or avoided all together. In addition to hormone data, biological and ecological data can be extracted from feces including DNA from the host, prey DNA, host microbiome, contaminant concentrations, parasitic loads, and diet information. While fecal sampling can provide a wealth of physiological, biological, and ecological information, important caveats must be considered. First, variation in metabolite concentrations in feces often depends on multiple factors including: 1) the species and sex of the individuals being sampled; 2) the species-specific and sex-specific hormone metabolism in combination with the immunoreactivity of the antibody utilized in the assay to quantify metabolite concentrations; and 3) the steroid extraction method being used to measure hormone metabolite concentrations. Furthermore, temperature and humidity can affect hormone metabolite concentrations in feces, which may be an important issue to consider if fecal samples are exposed to variable environmental conditions over inconsistent time scales prior to collection. The WECOS Lab is collaborating with researchers at The University of Montana and National Park Service to conduct controlled experiments for refining protocols to ensure reliable field based sampling as well as conducting assay validations for multiple species and multiple hormones to strengthen applications for non-invasive physiological sampling in free-ranging wildlife.