FACTORS INFLUENCING BODY CONDITION IN CABINET-YAAK ECOSYSTEM BLACK BEARS

• Main Author: Schwartzkopf, Caleb M
• Format: Text
• Language: unknown
• Published: ScholarWorks at University of Montana 2017
• Subjects: black bears; body fat; proportion body fat; body condition; cabinet-yaak bears; black bear forage affects; Ecology and Evolutionary Biology; Ursus arctos
• Online Access: https://scholarworks.umt.edu/utpp/152; https://scholarworks.umt.edu/context/utpp/article/1164/viewcontent/auto_convert.pdf

Grizzly bears (Ursus arctos) are a species in recovery. This holds true for the bears in the Cabinet-Yaak ecosystem. Low reproductive rates make recovery especially difficult for this species. These rates are affected by body condition, which has been found to predict reproductive success, both for grizzly and black bears (Ursus americanus). So what is it that affects body condition in black bears? We sought to answer this question by using research collected from black bears in this region. We analyzed several different variables, which included: vegetation and berry production, hunter harvest estimates, winter temperatures, age, and body metrics (i.e. weight, girth, shoulder height, etc.). We found that during the first half of the summer, body fat content of a black bear is most strongly related to body metrics, such as weight. If weight is taken out of the model, age, sex, current and previous year vegetation production, and previous year Huckleberry production appear. This changes for the second half of their year, in which current year vegetation production becomes more important. These results indicate that during the first half of the year, the energy consumed is put towards growth (for young bears) and building lean body mass. Also, previous year huckleberry production is important. The second half of the year is more crucial for building fat reserves. It is during this time of year that bears enter into hyperphagia, a state of prodigious eating where they prepare for hibernation. During this part of the year it appears bears rely on vegetation. Our results could indicate that limitations on population size in this region for grizzly bears.