Habitatgebruik, activiteit en jachtwijze van overwinterende roofvogels in de Göksu Delta, Zuid-Turkije

During a survey from 12-18 March 2000 in the Goksu Delta (14,480 ha) in southern Turkey, raptors were systematically censused by means of Point Transect Counts (8 points of 1 hour each on 6 days in the northeastern part of the delta, covering 5397 ha). Habitat characteristics, number and species of raptors and food items were quantified in 60 1 -km² plots in the same region. All together, c. 350 raptors in 17 species were estimated to use the delta, of which Marsh Harriers Circus aeruginosus with up to 250 individuals were most numerous. Other common species were Hen Harrier C. cyaneus, Common Buzzard Buteo buteo, Long-legged Buzzard B. rufinus and Kestrel Falco tinnunculus. Of these species, activity patterns (Tables 3-7, Appendix 3), habitat choice and density (Tables 1-2, Appendix 1) and perching sites were analysed (Appendix 2). Less common species were Black Kite Milvus migrans, Goshawk Accipiter gentilis, Sparrowhawk A. nisus. Golden Eagle Aquila chrysaetos, Spotted Eagle A. clanga, Imperial Eagle A. heliaca, Bonelli’s Eagle Hieraaetus fasciatus, Lesser Kestrel Falco naumanni, Merlin F. columbarius, Lanner Falcon F. biarmicus, Saker Falcon F. cherrug and Peregrine Falcon F. peregrinus. Some of these species were residents in the neighbouring Taurus mountain range north of the delta (Goshawk, Golden Eagle, Bonelli’s Eagle), others were wintering visitors in fluctuating numbers in response of weather conditions in Central Anatolia and food availability in the delta. The Goksu Delta turned out to be an important wintering site for 6-8 Spotted Eagles (in earlier studies even 10-15, but those studies were carried out during peak presence in mid-winter). The raptor species (and sometimes sexes within species) partitioned the available resources (food, perching sites, habitats) in such a way that inter- and intraspecific competition was mostly avoided. Open fields in wetlands, ploughed fields (especially when ploughed recently) and -less so- cereal stubbles were preferred habitats. Only Sparrowhawk and Goshawk were frequently using the fast-growing area of citrus plantations. Built-up areas were mostly avoided, except by Lesser Kestrels. The Goksu Delta is an important wintering site for raptors, and deserves protection from random shooting and habitat destruction (including massive use of pesticides).