The effect of summer cottages on land bird numbers in a Finnish archipelago

Abstract

The effect of summer cottages on land bird numbers was studied in the archipelago of SW-Finland . Bird fauna was very similar on cottage and non-cottage islands, with the following exceptions : The Wagtail Motacilla alba was significantly (P < 0.05) more abundant on cottage islands. The Oystercatcher Haematopus ostralegus and the Willow Tit Parus montanus were nearly significantly (P < 0.10) more abundant on noncottage islands. In the grouping of species based on nesting habits, birds nesting in nest boxes and other man-made structures were more abundant on cottage islands . The mean species richness and the Shannon-Wiener diversity index H' were significantly greater on cottage islands than on non-cottage islands. However, if the data are combined and treated as one sample for cottage islands and the other for non-cottage islands, the differences in species richness and diversity between island groups disappear .