Human activity and rehabilitation of birds of prey

Nowadays human activity is a major threat to wildlife. Birds of prey are particularly affected due to their location at the top of trophic pyramids and to their low numbers. Ethical and ecological considerations have led to the development of programmes to treat birds with injuries and their later release back into the wild. This paper deals with a crucial aspect of that programme: the survival success of birds of prey after such release. In a first study a sample of 16 rehabilitated buzzards (Buteo buteo) was released during different seasons in a farming area near the Po River. The birds had been taken to the Rehabilitation Centre (RC) nearby because of injuries due shots by poachers. After release the birds showed a progressive acclimatisation to the new environment, increasing their distance from the release site which suggested an improvement of the endurance of pectoral muscles, not fully acquired in captivity. Flight length was correlated with both distance from the release site (rs=0.133, P<0.001) and flight height (rs=0.314, P<0.001). They appeared to avoid human presence, and although the area chosen for this study had a high level of human population, this was not a major source of active interference. However, 3 birds died within 7 days by electrocution; one of which had been shot and injured a few hours earlier. A second study concerned a sample of 7 young long-eared owls (Asio otus). In recent years an increasing number of orphaned but uninjured Strigiform fledglings entered the RC. Most of these are collected by people from the base of trees because they have fallen either from the nest or when learning to fly. The fledglings are generally attended by parents but people believe they are injured or abandoned and need help to survive from predators. Such human behaviour is a consequence of the Italian people's increasing concern for to animal species. As a result, a large number of young owlets are unnecessarily captive reared and this is potentially affecting negatively their post-release survival in the wild. In contrast to the buzzards, owlets remained very close to the release site (less than 1700 m, mean: 342.3 ñ 56.8) and did not avoid human settlements. They too increased their distance from the release site (rs=0.796, P<0.001), but their survival rate was very low; in fact, 3 birds died within a few days and another was recaptured because it had fallen into a stream. The results show how rehabilitation of birds of prey is very important to aid recovery from injures, but is almost useless if not accomplished by good monitoring and surveillance of individuals after release into the wild.