VOLUME 22 - N. 1/2

Abstract:

The behavioural development in young Bearded Vultures released at the Argentera-Mercantour site prior to and immediately after departure from the artificial nest was analysed to provide a detailed description of the development of the main behavioural activities and to check for the occurrence of anomalies. Six individuals released from 1994 to 1996 were continuously monitored using telescopes. Regression analyses pointed out that three vultures during the period at the nest progressively increased the time spent on watching and feeding and hence decreased that spent resting. Then, after leaving the nest, most vultures progressively increased the time spent on feeding and flying and decreased that spent resting and walking. Percentages of significant regressions were lower in the first period (54%) than in the second (72%). This, together with the output of the analysis of covariance, suggests that the period at the nest may be more critical than that after leaving it. However, wing fluttering at the nest progressively and significantly increased in four out of six vultures. Once they have left the nest, most birds showed increased vigilance, selected roosting sites which were protected from terrestrial predators, and successfully interacted with crows at feeding sites. Finally, a few observations suggested that birds were able to drop bones autonomously. Our results, which are in keeping with previous observations, suggest that young vultures are able to overcome the difficulties they meet after release, probably because many behaviours are largely genetically controlled. Hence, we may assume that the final outcome of the reintroduction project of the Bearded Vulture in the Alps will not be significantly affected by the hacking technique employed.