engleski

Distribution and trend of breeding population of Rooks (Corvus frugilegus L.1758) in Osijek

Despite the fact that Rook was a typical bird of the steppe habitats, their numbers are nowadays increasing in urban areas. The aim of this study is to present the trend of breeding population and size of wintering population of Rook in Osijek town. Breeding population was established by counting Apparently Occupies Nest in Rook colonies during springs. Wintering population was studied by counting Rook at their roosts during 2014 and 2015. Software package TRIM was used to calculate the breeding population trend for last 23 years. On winter roosting localities 4000 Rooks were counted in average during winters of 2014 and 2015. During 2014 560 breeding pairs were counted in 13 colonies, while 623 breeding pairs were breeding in 12 colonies during 2015. Majority of the colonies (6) were classified as small (below 50 pairs), with average of 19 nesting pairs. Number of medium-sized colonies (50-100 pairs) varied between one in 2014 and four in 2015, while two big colonies (over 100 pairs) were present in both years. In the past 23 years the breeding population trend shows moderate decline, mainly because of the harassment of the colonies, nesting sites destruction and disturbance of breeding Rooks.

Rook ; breeding ; roosting ; Osijek ; Croatia

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