Oral Presentations
Influences of Individual and Environmental Factors on Body Condition in Female Elk
Presentation Type
Presentation
Faculty Mentor’s Full Name
Mark Hebblewhite
Faculty Mentor’s Department
Wildlife Biology
Abstract / Artist's Statement
Ungulate body condition is often considered to reflect the nutritional resources on the landscape but is ultimately influenced by more than forage as body condition integrates both energetic costs and benefits. Variation in female body condition is driven by both individual and environmental factors, such as age and reproductive effort or forage resources and predation risk, respectively. Our research evaluates how individual and environmental factors influence ingesta-free body fat (IFBF) in female elk (Cervus canadensis) to improve understanding and interpretation of body condition data. We collected seven years (2015-2021) of IFBF data from monitored and recaptured female elk (n = 139) in the Ya Ha Tinda (YHT) population in Alberta, Canada. We determined the best fitting generalized linear mixed-effects model to explain IFBF as a function of individual and environmental factors. Our top model included only prior summer calf survival as a predictor variable, with the second model (DAICc = 1.42) including both prior summer calf survival and average prior summer forage biomass. Our final top model predicts that a female elk whose calf survives the previous summer will have 3.28 percentage points (95% CI: 2.38, 4.19) lower body fat levels in winter compared to a female elk whose calf did not survive the summer. The importance of prior summer calf survival as an explanatory variable and the large size of its effect indicates that changes in reproductive costs driven by predation influence variation in female body fat more significantly than environmental factors like access to forage in this system. Our research helps scientists and managers interpret variation in ungulate body condition data and understand the important effects of juvenile survival on adult ungulate female body condition in the context of expanding predator communities across North America.
Category
Life Sciences
Influences of Individual and Environmental Factors on Body Condition in Female Elk
UC 326
Ungulate body condition is often considered to reflect the nutritional resources on the landscape but is ultimately influenced by more than forage as body condition integrates both energetic costs and benefits. Variation in female body condition is driven by both individual and environmental factors, such as age and reproductive effort or forage resources and predation risk, respectively. Our research evaluates how individual and environmental factors influence ingesta-free body fat (IFBF) in female elk (Cervus canadensis) to improve understanding and interpretation of body condition data. We collected seven years (2015-2021) of IFBF data from monitored and recaptured female elk (n = 139) in the Ya Ha Tinda (YHT) population in Alberta, Canada. We determined the best fitting generalized linear mixed-effects model to explain IFBF as a function of individual and environmental factors. Our top model included only prior summer calf survival as a predictor variable, with the second model (DAICc = 1.42) including both prior summer calf survival and average prior summer forage biomass. Our final top model predicts that a female elk whose calf survives the previous summer will have 3.28 percentage points (95% CI: 2.38, 4.19) lower body fat levels in winter compared to a female elk whose calf did not survive the summer. The importance of prior summer calf survival as an explanatory variable and the large size of its effect indicates that changes in reproductive costs driven by predation influence variation in female body fat more significantly than environmental factors like access to forage in this system. Our research helps scientists and managers interpret variation in ungulate body condition data and understand the important effects of juvenile survival on adult ungulate female body condition in the context of expanding predator communities across North America.