Persecution of birds of prey in Flanders between 2011-2019 : a retrospective study

For decades birds of prey have been under the protection of European law, but deliberate or unintentional killing is still a large scale problem in Europe. In an effort to monitor illegal practices in Belgium, the Agency of Nature and Forests (ANF) of the Flemish government established several bird of prey hotlines in 2006. Whenever a suspicious dead bird of prey is encountered by the general public, foresters and inspectors of the ANF through passive surveillance, the carcass is necropsied to assess whether the death is from an illegal cause. If shooting was suspected, carcasses were screened for the presence of metallic objects and accompanying lesions using radiographic images. If intoxication was suspected, samples were further sent for toxicological investigation. The presence of cholinesterase inhibitors, strychnine, anticoagulants was investigated qualitatively. In total, 315 birds of prey, of which 260 were common buzzards, were collected between January 2011 and December 2019. As the ANF occasionally collected more than one bird at the same location, these 315 birds were comprised in 226 suspicious mortality events. In 36.7% (83/226) of all mortality events, an illegal cause of death was found, with poisoning being demonstrated in 32.3% (73/226), shooting in 4% (9/226) and entrapment 0.01% (2/226) of all cases. Cholinesterase inhibitors were the most commonly used toxins, being detected in 84.9% of the toxicological cases. With 116 individual, common buzzards were the species most involved in illegal practices. In conclusion, birds of prey are still frequent victims of illegal practices, with the common buzzard having the highest number of individuals being killed through illegal practices. Whenever the presence of toxins was demonstrated, cholinesterase-inhibitors were the most commonly used toxic substances