Introduction

A small, common shorebird similar in appearance to its Eurasian counterpart, the Common Ringed Plover (Charadrius hiaticula), the Semipalmated Plover generally nests in open sites near sub-arctic lakes, marshes, and rivers. A few populations are found south of the sub-Arctic in north temperate regions. This species is socially and most often genetically monogamous, and both sexes actively care for eggs and their precocial chicks. A medium- to long-distance migrant, it winters mainly in marine habitats, rarely inland. The Semipalmated Plover is among the few plovers whose numbers are apparently increasing, perhaps owing to its versatility in food and habitat choice, its wide-spread coastal winter distribution, or its habitat expansion in the sub-Arctic as a result of disturbance by both humans and arctic geese.

The open habitat and relatively tame nature and ease of capture of this species make it ideal for study on its breeding grounds. From Churchill, Manitoba, detailed long-term information is available on its breeding phenology, behavior, and population structure (Nol et al. 1997, Sullivan Blanken and Nol 1998, Flynn et al. 1999). Some comparative data are also available from a disjunct population of plovers nesting on the Queen Charlotte Islands in British Columbia (Cooper and Miller 1997).

Because this species generally occurs in smaller and more dispersed flocks than do other shorebirds, it has rarely been the focus of migration studies. Detailed studies of its winter distribution will be important in establishing global population sizes of this widely dispersed species.