[The decline of one of the most threatened European birds of prey: 41 years of observations on the Lanner, Falco biarmicus in Sicily]

[The results of a research on Lanner in southern Sicily, carried out between 1978 and 2018, are reported. 32 Lanner nesting territories have been taken into account, from sea level up to 1200 m of altitude. Until 2005, there were about 25 nesting pairs in the area; but in the following years there was a steady decline. At least 16 sites have been gradually abandoned because of human persecution and, at a lesser degree, of the interference with the Peregrine falcon, Falco peregrinus, and the Bonelli’s eagle, Hieraaetus fasciatus. At present, the number of Lanner pairs breeding in the study area is around 12. From 120 nesting attempts followed, 216 youngs fledged, with a productivity of 1.80, with breeding success of 1.98, fledging rate of 2.40. Out of 109 nests in which there was egg laying, 90 were successful. Out of successful nests, 11 fledged 1 young (12.2%); 37 nests 2 youngs (41.1 %); 37 nests, 3 youngs (41.1%); 5 nests, 4 youngs (5.6%). The number of pairs that have laid eggs, in relation to the number of the monitored nests, was of 90.8%. The ratio between the number of nests in which youngs were raised and the number of pairs that laid their eggs was 88.1%. The ratio between the number of nests from which youngs fledged and the number of breeding pairs was 93.7%.The number of successfully breeding nests, in relation to the number of monitored nests, was 75%. As regards the diet, birds represent Lanner’s most frequent preys. Out of the 415 preys identified, 383 (92.3%) are made up of birds, 29 (7%) by small mammals, 3 (0.7%) by reptiles. In addition to human persecution, the population of Lanner in Sicily is influenced by interspecific competition, particularly with the Peregrine falcon; but in 2 cliffs, about 1 km long and with a substantial wealth of prey, both falcons have been successfully reproducing for over 10 years]. [Article in Italian]

Modelling the risk of collision with power lines in Bonelli’s Eagle Hieraaetus fasciatus and its conservation implications

SummaryPower line casualties are considered one of the main causes of mortality in the endangered Bonelli’s Eagle Hieraaetus fasciatus, although little is known about factors involved in collisions with wires and their consequences at population level. We studied 18 radio-tracked individuals to determine the risk of collision with power lines at two spatial scales (flight height and span crossings). Through logistic regression modelling we found that the risk of collision was mainly determined by eagles’ home range use, being reduced in kernel 80%, kernel 95% and MCP respectively to 0.421, 0.114 and 0.032 times in comparison to risk associated to the 50% kernel area. In addition, the risk of collision increased in open habitats (around 1.5 times higher than in forested habitats) far from urban areas (2.345 times higher than near urban areas) that were good for hunting, and in cliff areas used for breeding and roosting, where eagles fly at a lower height (the probability of eagles flying at a low height was 1.470 times higher than in forested habitats). A significant positive correlation was found between territorial turnover rates and the risk ascribed to transmission lines with earth wires in 15 breeding territories. Moreover, this correlation had a higher significance for the 50% kernel area when transmission without earth wires and double circuit distribution lines were added, although no correlations were encountered for distribution lines. These results suggested that power line collisions might be more important than previously reported as a cause of mortality for the species and thus conservation actions should be applied in order to minimise their effects on population dynamics. Predictive models may be a useful tool in careful planning of new power line routes and the wire-marking of the existing ones. Kernel areas should be used rather than fixed radii given that distances from nests may not adequately match the risk of collision.