No abstract

The Bonelli's eagle is one of the rarest and most threatened birds of prey in Europe, which means that great efforts are being made to guarantee its conservation. One of the lines of work is the reintroduction of specimens in areas where the species has recently become extinct and those in which the factors that caused its disappearance have been corrected. The present study presents the results of one of these reintroduction projects carried out in Navarra, Northern Spain, between 2011 and 2021. Forty-seven individuals (36 born in captivity and 11 from wild nests) were released in ve places close to historical territories. After those 11 years of work, the occupation of two of the historical and the creation of a new one has been achieved. 44.68 % of the birds died in the rst year after their release and 19.14%, during the rst month in the eld. No signi cant differences were found associated with the sex or the origin of the specimens in survival during the rst month or during the rst year after release. 48 % of deaths were related to anthropogenic causes (electrocution, wind farm collision, indeterminate trauma, shooting and poisoning), while 44% were due to predation by mammals or big raptors. This last result had not been described until now and suggests that, when the causes of death of human origin are corrected, those of natural origin appear. The application of this type of actions as a conservation tool for the species is discussed.