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.