Nest-hole selection as defence measure in breeding Swifts (Apus apus)

COLOMBO A. and GALEOTTI P.

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Abstract:

During the 1990-1991 breeding seasons we studied factors affecting Swift nest-hole selection, i.e. exposure, height, dimensions, type of holes and dispersion, in Pavia, Northern Italy. Exposure was not a significant factor, while in most cases Swifts nested at a height of 9-14 m in very small holes, often barely large enough to let them in. Holes were the sites selected in most cases; however a number of Swifts used the spaces under tiles, and a small number nested under eaves or behind shutters. Swifts were found nesting at 1-2 m maximum distance, confirming that nest-aggregation is another important factor in hole selection.