EN
The bird species in the three different vegetation zones – dry forests, humid forests, and coastal plain – of the Istranca Mountains in north-western Turkey were investigated. A total of 79 days of observations consisting of 17 months were performed on a fifty-one kilometre line, transecting the mountains. One hundred and forty-nine bird species were determined during the weekly periodic observations carried out between early 1989 and late 1990. Of these 55 were resident, 24 were winter visitors, and 62 were summer migrants. Eight species were seen occasionally and were therefore described as accidental. The statistical tests revealed that the frequencies of the resident, winter visitor, and summer migrants were different in the study area in which winter visitors were fewer than the resident and summer migrants. The frequencies of the bird species in the three different zones regarding the pooled data also different that the dry forests had fewer bird species than the coastal plain.