Gender- and age-class specific reactions to human disturbance in a sexually dimorphic ungulate (2005)

Loehr, J., Kovanen, M., Carey, J. et al.

Abstract

According to optimality theory, an individual's characteristics should play a major part in determining antipredator strategies. We studied behavioural reactions to human presence of gender and age classes of 35 thinhorn sheep (Ovis dalliNelson, 1884) in late winter 2001 in Faro, Yukon Territory, Canada. The behaviour of undisturbed sheep was observed from distances of 400?1200 m and compared with the behaviour recorded when one or two people were in close proximity to the sheep. Ewes decreased bedding and increased foraging when humans were present, but there were no changes in these behaviours in rams. Disturbance caused an increase in vigilance and a trend was found for adults to react more strongly to disturbance than juveniles. We demonstrate the importance for disturbance research of gaining detailed information about all different kinds of population members and using applicable statistical tests in the data analyses.