Stress response of boreal woodland caribou, moose, and wolves to disturbance in eastern Manitoba

Abstract

Disturbance can provoke a chronic (long-term) stress response in wildlife, and can contribute to population declines. I examined the stress response of boreal woodland caribou, moose, and wolves to disturbance in eastern Manitoba by measuring cortisol concentrations in hair. Caribou cortisol concentrations were greatest for the three most southern populations, and increased with decreasing home range size. Intermediate logging (6-21 years) provided the best explanation for individual variation in caribou cortisol concentrations. Disturbance did not affect moose cortisol concentrations, but cortisol concentrations were higher in moose killed by wolves than moose collected by humans, suggesting that chronic stress in moose is linked to poor body condition and increased vulnerability to wolf predation. Wolf cortisol concentrations increased in 2012 and 2013 compared to 2011 following increased harvest pressure, and were higher in females. However, neither winter severity nor variation in wolf diet affected wolf cortisol concentrations.