Wild deer populations in many countries exist at unnaturally high densities due to predator absence, causing chronic welfare problems from disease, starvation, and vehicle collisions.
Wild deer welfare presents complex challenges arising from ecosystem disruption. The absence of natural predators in most of their range means that deer populations are managed primarily through human hunting, with welfare implications both for the hunting process and for the consequences of inadequate control. Deer at very high population densities experience chronic welfare costs including increased disease burden, reduced food availability, and territorial aggression. Chronic wasting disease causes extended suffering before death and is spreading geographically. Vehicle collisions kill or injure many thousands of animals annually, with injured deer suffering without treatment in most cases. The welfare calculus in deer management involves comparing the diffuse chronic welfare costs of overpopulation against the acute welfare costs of hunting and accepting that human management has replaced the regulatory role of predators.