Introduction

The Savannah Sparrow is widespread and abundant in open habitats throughout North America although, like other grassland sparrows, it is often overlooked because of its secretive habits. During the breeding season its persistent buzzy song can be heard in agricultural fields, meadows, marshes, coastal grasslands, and tundra. Insects and other arthropods are its main prey in summer; in winter and on migration its diet shifts to small seeds encountered while foraging on the ground. Most populations are migratory, although salt marsh populations breeding in the southwest are mainly resident. As in many passerines, annual mortality usually exceeds 50%. Surviving juveniles and adults tend to return to the same natal or breeding site. Such strong philopatry has resulted in substantial geographic variation; 17 subspecies are recognized, including the Ipswich Sparrow, which breeds on Sable Island, Nova Scotia.

This species was named by Alexander Wilson for the town of Savannah, GA, where the type specimen was collected. Sexually monomorphic in plumage, in body size males average larger than females. Polygyny is routine in many populations, especially in the Canadian Maritime provinces. Several features of the biology of Savannah Sparrows make it attractive for comparative studies of ecology and evolution, including its broad geographic distribution, occurrence in a variety of habitats, high breeding densities, and natal philopatry on islands.