Indicators of nutrition and reproduction in female woodland caribou receiving supplemental feed in British Columbia

Adequate nutrition is closely associated with animal survival, reproduction, and population growth. Supplementary feeding, the provisioning of food to offset reduced availability of natural food and / or improve individual and population attributes, is often used as a conservation tool to reverse the decline of threatened populations. Most woodland caribou (Rangifer tarandus caribou) populations in British Columbia are declining throughout their range due to habitat alterations caused by human activities. In response to these declines, various management strategies have been employed to halt population declines and increase the number of caribou in BC. Supplemental feeding for caribou conservation began in 2014, with highquality food pellets provided to free-ranging caribou in the Kennedy Siding herd each fall. The goal of this program is to improve body condition, increase winter survival, and improve reproductive outcomes. Feeding combined with predator reduction appears to have had a positive effect on caribou, with the herd growing by approximately 16% per year. I used multiple indicators of nutritional condition and reproduction to investigate the effects of supplemental feeding on body condition and population growth among female caribou in the Kennedy Siding herd. I used body mass, visual body condition scores, fecal and hair cortisol, fecal triiodothyronine, and hair δ15N to evaluate the changes in physiological and nutritional condition over the feeding period and to assess interannual variation in condition. I compared indicators measured in female caribou with a weaned calf in the fall to those without a calf to assess the effects of lactation and calf rearing on condition. I used a combination of fecal progesterone measurements and GPS collar movement data to assess the potential effects of fall supplemental feeding on ovulation, parturition, and calf survival. My results suggest that females with calves may be more vulnerable to nutritional limitation compared to females without calves due to the nutritional costs of lactation and calf rearing. Furthermore, I found differences in indicators of condition between years, highlighting the need to account for environmental conditions when considering nutrition. Indicators of nutrition suggested that all caribou had the capacity to become pregnant, regardless of age, body condition, or whether they had a calf at heel or not. Total parturition rate was 87.5% and calf survival was 74.3% in the Kennedy Siding herd, which are at the high end of comparable rates reported in unfed caribou herds in BC. Combined, my findings suggest the mechanism that in which supplemental feeding contributes to population growth is by supporting the deposition of body fat and protein reserves, thus increasing the proportion of females that have successful pregnancies and potentially also the proportion of calves that survive until the fall. My research represents some of the first longitudinal monitoring of endocrine activity in woodland caribou and contributes to understanding the role of nutrition in caribou conservation.