Die Alpendohle (Phyrrhocorax graculus) im Stadtgebiet von Innsbruck, Tirol: Bestandesgrößen, Bestandesdynamik, Bestandesstruktur und Raumverteilung.
Ber. nat.-med. Verein Innsbruck 87: 307-326.
Abstract
The Alpine Cough (Phyrrocorax graculus) in the Municipial Area of Innsbruck, Tyrol: Size, Seasonal Dynamics, Space Use and Social Structure of Winter Populations Synopsis: Standardised weekly counts (from February 1997 until April 1998) covering 11 km 2 of the municipial area of Innsbruck, Tyrol (575 m asl) where performed in order to investigate the number, seasonal dynamics and space use of Alpine Choughs wintering in Innsbruck. In additi-on, Alpine Chough behavioural data were collected using the focal animal sampling method. The number of Alpine Choughs steadily increased from autumn, to mid-winter (maximum approx. 1000 birds) and early spring and decreased towards late spring although the city area was also used by Alpine Choughs during the summer month proper. Birds were unevenly distributed over the city area, showing preferences for districts dominated by higher buildings, i. e. skyscrapers and blocks consist-ing of multi-storey buildings. Average flocks sizes were largest in midwinter, when flocks sometimes comprised more than 200 birds, and smallest in autumn. The age structure of the wintering popula-tion changed during the winter. The percentage of adult birds increased from 69 % in early winter to 94 % in late winter. Similarly, the percentage of mated birds within flocks increased form 3 % in autumn to 40 % in spring. According to the directions of their departure it can be assumed that all Alpine Choughs visiting Innsbruck live in the limestone mountain ranges north of Innsbruck, roost-ing sites being located at distances from 5 to 13 km from the city centre.
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