Short-toed Eagle Circaetus gallicus population monitoring at the Apuane Alps migration watch-site (Tuscany)

Premuda G., Belosi A., Viviani F., Franchini M.

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Abstract:

The aim of this study is the monitoring of the Short-toed Eagle population breeding in the Italian Peninsula, through visual counts performed at the Apuane Alps raptor migration watch-site. The “circuitous migration” performed by the species makes it possible to know the source and destination of the migrating eagles. Total migration counts were collected at the site over a six-year period 2008-2013 in March (max 1845, average 1472) and September (max 1934, average 1459). The total spring and autumn counts are compared to validate the reliability of the observations. Data about Short-toed Eagle population trends are analyzed over a ten-year spring sample period 2004-2013, showing the median date (average on 16 March and 21 September) and the peak passage (on 14 March and 21 September). Two samples of 12-day peak periods in spring and autumn over nine years (2005-2013) are compared to validate the trends and the reliability of the counts. Trends of the mean hourly rate over a nine-year period (2005-2013) in spring and autumn are also analysed. Our results allow us to estimate the population size of Short-toed Eagles breeding in Central-Southern Italy (514-872 pairs) and to provide an updated estimate of the entire Italian population (626-1025 pairs). Our data show that Short-toed Eagle population trends have been positive over the last ten years (+102.5%, +10.25% yearly average) and we recommend that the population trend status of the species in Italy be upgraded to “Increasing”.