The choice of fishing lakes by the Red-throated DiverGavia stellataand Black-throated DiverG. arcticaduring the breeding season in south-west Sweden

Abstract

Relationships between abundance of foraging Gavia stellata and G. arctica in potential fishing lakes in south-west Sweden in relation to density of fish (< 20 cm, measured as the mean number of fish per catch effort with gill nets), lake surface area, shoreline development, water transparency and location of nest sites were investigated through multiple regression analyses. For the period of incubation, hatching and feeding of small young (end of May-June) the analyses did not reveal any clear patterns, but indicated that presence of G. stellata was related to large lake surface area and presence of Acerina cernua, and G. arctica to high water transparency. During July (feeding of medium-sized to large young), G.stellata primarily occurred in lakes with high density of cyprinid fish or Acerina cernua, and located close to breeding lakes. The distribution of G. arctica foraging alone or in pairs was related to high shoreline development, whereas the occurrence of birds fishing in groups to high density of ...