Hunting is widely used to manage deer populations and their impacts on ecosystems. Various management strategies can be used to ensure that the hunting bag is of adequate size and composition to actually control population growth, including the abolishment of hunting quotas. However, the actual impacts of hunting without quotas on deer harvest are rarely assessed.

Here we evaluated the impact of hunting without quotas on roe deer (Capreolus capreolus) in Schleswig-Holstein, Germany, by comparing the hunting bag seven years before and after the abolishment of hunting quotas in the federal state and state forests. We used linear mixed models and a counterfactual approach to separate the impact of hunting without quotas from confounding factors that also influence roe deer harvest.

We found no significant change in annual harvest densities (i.e., the number of harvested roe deer per 100 ha) overall, but a significant increase in harvest densities in state forests. This increase was most pronounced in forest districts where the forest manager changed during the study.

Hunting without quotas altered the harvest sex ratio from a female-dominated to a male-dominated one in both the state forests and the entire state. Despite this decrease in relative number of females harvested, hunting without quotas still led to an increase in the absolute number of harvested females in the state forests, while fewer females were harvested across the entire state.

Synthesis and applications: Hunting without quotas increased the total and female harvest density in state forests, but actually decreased female harvest across the state. Thus, such hunting could result in source-sink dynamics that make actual reductions of roe deer densities in state forests challenging. Our study illustrates the usefulness of counterfactual approaches to objectively evaluate the effectiveness of hunting regulations as a wildlife management tool. Such approaches could be applied more routinely in the future and may be extended to evaluate the impact of hunting regimes on actual deer densities and their effects on (forest) vegetation.