Stopover Ecology of Some Passerines at Ankara (Central Turkey)

In autumn 2002 we studied little known passerine migration at a woodland patch within the Middle East Technical University (METU) campus in Ankara (Turkey). A total of 954 individuals of 35 passerine species were mist-netted, ringed, measured, weighed and fat-scored (after Busse 2000). Blackcap (Sylvia atricapilla) and Willow Warbler (Phylloscopus trochilus) were the two most common species, with 308 and 145 individuals caught, respectively. Both are passage migrants at METU, recorded from mid-August to late October, representing several waves.

Only 11.5% of Blackcaps had the fat score of T₆ and above, and among 20 retraps only 2 gained fat significantly. All the other retraps lost fat, stayed the same, or increased 1-2 scores at most. In contrast, Willow Warblers, as true trans-Saharan migrants, had the much higher proportion (46%) of individuals with fat scores of T₆ and above. Most retrapped individuals gained fat, some with already high levels stayed the same, while none lost fat. We interpret these data in terms of known migratory ranges, diet types and habitat patch quality.

Although daily catches were low, a diverse range of species used METU as a stopover site. Fat deposition rates (of up to 50% of body weight within a week) suggest that the study site provided a high quality stopover habitat for most migrants. In Central Turkey, such suitable habitats with trees or tall shrubs are scarce, and therefore, crucial for migrants.