Russ A. Walton1,3 and Kenneth G. Wright2
1 3160 Bank Road, Kamloops, B.C. V2B 6Z5; e-mail: russ_walton@telus.net
2 360 St. Paul Street West, Kamloops, B.C. V2C 1G4
3 Corresponding Author
Abstract: We examined the seasonal fluctuations in numbers of American Dippers (Cinclus mexicanus) on three watercourses near Lillooet, British Columbia. Monthly surveys were carried out between December and August over three consecutive years (2000-2002) on a 10.6 km survey route. Dipper densities peaked in winter, achieving maximum densities of 10.8 birds per km of stream channel in December. Summer densities were up to 50-fold lower, ranging from 0.2 to 0.5 birds per km. All three watercourses were influenced by hydroelectric generation facilities but birds avoided the least natural watercourse, using the power canal only when numbers in the survey area exceeded 90 individuals. Our study indicates that this area is an important wintering ground for dippers and it demonstrates the importance of using multi-season surveys for assessing true habitat value for resident and migratory birds.
Key words: American Dipper, Cinclus mexicanus, winter density, season, riverine bird surveys, Coast Mountains, British Columbia
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