Selection of settlement areas by juvenile Bonelli's Eagle in Catalonia

We observed Bonelli's Eagles (Hieraaetus fasciatus) outside their breeding range in Catalonia (northeastern Spain) to identify the main dispersal areas of juvenile eagles in the Central Catalan Basin. Autumn counts were conducted to determine the size of the nonbreeding population in the main dispersal area and to analyze factors leading to the selection of settlement areas by juveniles. The permanent eagle population in the area was estimated at about 18 >1-yr-old eagles for an average density of 0.90 eagles/100 km(2). Number of eagles in the area <1-yr old fluctuated seasonally between 17-94 eagles with the number reaching a maximum in early autumn followed by a rapid decline during winter. Juvenile settlement areas appeared to be selected based on gamebird and rabbit abundance, rather than on landscape variables. As a consequence, game management measures appeared to be key in the conservation of Bonelli's Eagles.