Fig. 1.
Map of the ∼1,600-km2 house sparrow study system at the Helgeland coast in Norway. The 18 islands in the study metapopulation are shown in black, and other islands (without sparrows) and the mainland are in gray. The eight islands included in the current study are indicated with their names. The study system consists of two distinct habitat types: 1) farm islands (turquoise names), and 2) nonfarm islands (orange names), where the sparrows live on dairy farms and in gardens, respectively.