A shot in the dark: Sport hunting of declining corvids promotes the inadvertent shooting of threatened red-billed choughs

摘要

Inadvertent shooting of protected species due to misidentification or spatio-temporal coincidence with more abundant target species of similar appearance and habits is a frequent side-effect of sport hunting. Protected corvid species of special conservation concern were present in all Spanish Autonomous regions where hunting of corvids of similar appearance and habits is legally permitted.We assessed the extent to which Western jackdaws (Corvus monedula) and Red-billed choughs (Pyrrhocorax pyrrhocorax) shared distributions in central Spain, and whether this can cause mortality and temporary and permanent crippling of threatened and strictly protected choughs. About 1000-3000 'black corvids' were annually hunted in the Madrid region without species-specific identification according to official statistics. Assuming that these corvids were mostly jackdaws, this accounted for about 5-20% of the total estimated winter population of this declining species. Jackdaws and choughs shared local distribution ranges and their abundances were spatially correlated during winter. The abundance of jackdaws was positively correlated with the estimates of killed black corvids (including jackdaws and Carrion crows, Corvus corone, which were not identified to species in hunting statistics). As with jackdaws, hunting was the main cause of mortality of choughs. The impact of hunting on non-target choughs can be strong-even live individuals can be temporarily affected by damage to flight feathers or other wounds, and birds can be crippled for life when shooting affects the bill or other body parts. To date, there is no framework for informed decisionmaking in game management or any published evidence-based or standardized criteria supported by scientific research aimed to establish a hunting status or quotas for corvids and many other common bird species in Spain. This combination of subjectivity and a lack of information makes it near impossible to establish a harvesting scheme without putting at risk the populations of target and non-target species. Given the strong decline of currently hunted corvids in Spain (especially the jackdaw), the complete prohibition of hunting these species is urgently encouraged to attempt to avoid exacerbating the collapse of their populations and that of non-target species.