Testing the efficacy of different Larson trap designs for trapping Egyptian geese (Alopochen aegyptiacus L.) in Flanders (northern Belgium)

In Western Europe, the Egyptian goose is considered one of the most rapidly spreading invasive bird species. Listed as a species of Union Concern by the EU, it is subject to restrictions and measures and European Member States are urged to develop management strategies. Since common techniques such as shooting, moult trapping and egg control have been inadequate at lowering population numbers, there is a high demand for alternative effective control strategies. Here, we report on field trials testing the use of walk-in traps with live decoy birds. Trials were spread out over several years to establish optimal trapping season and trap design and to explore different deployment options. We found that in Belgium the breeding period was the optimal season for deploying traps, which suggests the territorial response is the main driver of trapping efficiency. Land-based designs performed significantly better than other trap types at catching Egyptian geese and had far fewer by-catches. The strategy in which traps were deployed at short intervals over various locations had the highest efficiency. We conclude that the use of land-based versions of this trap type can be a useful addition to a wider management strategy when used on a large scale and aimed at trapping adult birds prior to breeding. Given the high effort needed for this type of trapping and the expected effectiveness of other management techniques, the method is best combined with post breeding shooting. KVM: research conceptualization, sample design and methodology, investigation and data collection, writing – review and editing.