Ecological distribution and population densities of raptors in the inner and outer zone of a Central European city

Abstract

Five raptor species were recorded as breeding in the city of Wrocław (293 km 2) during the years 2002-2010: Falco tinnunculus (2.4 pairs per 10 km 2), Buteo buteo (4.1 pairs/10 km 2 of wooded area), Accipiter gentilis (3.1 pairs/10 km 2 of wooded area), Accipiter nisus (1.6 pairs/10 km 2 of wooded area), Circus aeruginosus (0.2 pairs per 10 km 2). All these species have increased in numbers over the last 20-30 years, both in the inner and outer zone of the city. Falco tinnunculus is a well-established raptor in the inner part of the city, while Accipiter nisus, A. gentilis, Buteo buteo started to infiltrate to the inner zone. In the last 70 years, a few cases of nesting were recorded for four other raptor species in Wrocław: Milvus migrans, Milvus milvus, Pernis apivorus and Falco subbuteo, but none of them was recorded in the inner zone of the city. Abundant and stable food supply (small mammals, columbids, corvids and small passerine birds), and freely available nesting and perching sites may contribute to this success.