Breeding Bird Community Densities and Species Richness in Lakes

Multiple regression analysis revealed that breeding bird community densities in eleven south Swedish lakes were positively correlated both with total phosphorus concentrations of the water and with the percentage of fen area. Eutrophic lakes support more species than oligotrophic ones, but a man-made increase in productivity does not lead to higher species richness in formerly oligotrophic lakes. Species number correlates positively with pH and shore development. About the same species number occurs in single lakes and in similar sized parts of large lakes. It is suggested that lakes, in northern Europe, appear to the birds as any other major continental habitat. The slopes of species-area relations for lakes are computed for vascular plants, invertebrates, fish, and birds and reasons for the low slopes (z < 0.21) are discussed.