Effect of human activities on the behaviour of breeding Spanish imperial eagles (Aquila adalberti): management implications for the conservation of a threatened species

摘要

We studied (14 500 h of field observations during 20 breeding attempts by 10 pairs) the effects of human activities on the behaviour of breeding Spanish imperial eagles. The probability that human activities around nest sites provoked a flight reaction varied significantly among territories and among types of activity, and increased when the distance between the activity and the nest site decreased, and increased when the number of people involved in each intrusion was higher. Pedestrian activities (mainly by hunters, campers and ecotourists) caused more flight reactions than vehicles. Overall, the probability of a reaction increased sharply when activities occurred at less than 450m from the nest, but was negligible if they occurred at 800m. Reaction probability was lower in territories with higher intrusion frequencies (which suggests that some habituation occurs), where the nest was not visible from the tracks, and in less 'plain' or 'accessible' territories. Hatching rate was affected negatively by the frequency of human activities. Our results suggest that the critical inner buffer zone around Spanish imperial eagle nests should be established at a minimum radius of 500m. and the vulnerable zones at a minimum of 800m, bearing in mind the physiography of the terrain and the visibility of the nests. Finally, in future studies of nest-site selection with this species, it would be advisable to use a variable that quantifies (through field observations) human disturbance frequency.