Habitat use by short-toed eagles Circaetus gallicus and their reptilian prey during the breeding season in Dadia Forest (north-eastern Greece).
Abstract
The area surrounding and including Dadia Forest, north-eastern Greece, has a great diversity of breeding raptors, including many species of conservation concern. The distribution of reptiles was investigated during 1996 at 5 plots in each of 9 different habitat types (intensively cultivated areas, non-intensively cultivated areas, shrublands, pine forest, mixed pine-oak forest, oak forest, degraded oak forest, grasslands with sparse shrubs and rocky areas) to assess the importance of these habitats for foraging by short-toed eagles (Circaetus gallicus). The habitat mosaic was dominated by Pinus brutia, Pinus nigra, Quercus conferta, Q. pubescens, Q. sessiliflora and Q. cerris. In addition, data on the diet of the species was collected from direct observations at nests during 1996-97. C. gallicus relied heavily on snakes for food, the most important prey species being the grass snake (Natrix natrix). Montpellier snakes (Malpolon monspessulanus) and large whip snakes (Coluber jugularis), which also featured in the diet, were distributed across all habitat types, but N. natrix was concentrated in areas of mainly intensive, but also non-intensive, cultivation. Analysis indicated that short-toed eagles concentrated their foraging efforts in intensive and non-intensive cultivation and grasslands. Forested areas were largely avoided by foraging eagles. For C. gallicus, the distribution and abundance of prey items on the ground did not reflect food availability. The possible effect of changes in habitat management on the population of C. gallicus in Dadia is discussed, with particular reference to the establishment of exclusion zones that could result in progressive canopy closure.