Breeding biology of Bonelli’s Eagle (Aquila fasciata) in Cyprus

Abstract The Bonelli’s Eagle exhibits a wide geographic distribution yet remains relatively understudied on the island of Cyprus. Between 1999 and 2002, we examined 32 pairs of Bonelli’s Eagles, totaling 64 breeding attempts. During this period, a total of 116 eggs were laid, with an average clutch size of 2.0 ± 0.1 eggs per pair. Incubation, predominantly performed by the female, lasted an average of 38.7 ± 0.2 days. Of the eggs laid, 71 hatched, resulting in an average hatching rate of 82.6%. Hatchability varied, with the highest rate (91.3%) observed in 1999 and the lowest (76.2%) in 2001. Nestlings spent an average of 61 ± 0.5 days in the nest before fledging. Remarkably, 92.6% of pairs successfully fledged young (n = 60), with a mean breeding success of 1.6 ± 0.1 fledglings per pair. Significant differences were observed in the average number of eggs laid, hatched, and young fledged between the two types of habitats. Nest sites varied in altitude, ranging from 170 to 1,242 meters, with a nearest-neighbor distance between adjacent nests averaging 7.86 ± 0.43 kilometers.