Collateral damage: hunting effects on non-target species and groups

Human hunting in terrestrial ecosystems is widespread and can have both direct and indirect impacts on non-target wildlife species and demographic groups, a topic that has received limited attention. I here provide a systematic review covering (1) direct hunter errors (shooting non-target species/sex/age group), (2) the direct disturbance by hunters or dogs to non-target wildlife, and (3) the indirect effects of hunting through the creation of a landscape of fear in non-target wildlife. Overall, these issues were more commonly reported for hunting birds, in particular waterfowl, than mammals. For waterfowl hunting, direct shooting and disturbance effects on non-target species was a recurring issue. A few studies of non-waterfowl species also involved a vulnerable, non-target species being shot due to similar appearance to a commonly hunted game species. In contrast for mammals, no study addressed the direct impact of hunting on non-target species or demographic groups. For disturbance and fear effects in mammals, several studies have shown no or limited effect on non-target species. However, the use of dogs appears to have the potential to disturb wildlife more broadly during ongoing hunts, but whether this notably affects non-target species or groups remains to be documented. Unique experiments have demonstrated disturbance and fear effects during the male elk hunting season on both female elk and Odocoileus deer. Studies on effects of selective hunting should broaden focus beyond target species and groups.