Impact of wildlife culling on the behaviour of a highly social herbivore

Wildlife culling is used to control overabundant populations of animals, particularly herbivores, and can be an effective yet controversial management tool. While the ecological outcome of culling has been extensively studied, little research has been done on the behavioural impacts of culling on the animals remaining in the population. We intensively studied multiple populations of eastern grey kangaroos (Macropus giganteus) in the weeks immediately before and after an annual cull to examine how culling affects the behaviour of remaining animals. While the cull reduced overall population numbers by 30-60%, there was little impact on group sizes of individual kangaroos within populations, a first pass indicator of sociality. The proportion of kangaroos observed being vigilant increased by 70% in the weeks following the month-long culling event, but there was no discernible change in any other behaviour (foraging, resting or reproductive behaviour). In particular, there was no increase in stress behaviour after culling. Taken together, the practice of culling as a management tool of this iconic, highly social herbivore did not impose lasting behavioural changes on surviving kangaroos. Without comprehensive behavioural assessments like this being made of wildlife management strategies, it is difficult to obtain a clear picture of the impacts of such practices on animals remaining in the population. This is especially problematic for social species like macropods and other large herbivores where changes in population composition could have lasting flow-on effects on stress and wellbeing.