2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 124 



Statistical reliability of the measurement differences recognized 

 in this paper was determined by Robert Heath, Bio-statistician of 

 the Bureau of Sport Fisheries and Wildlife. 



Geographical and Ecological Distribution 



The hermit thrush is one of the most widely distributed migratory 

 birds in North America. Its breeding range is extensive, including 

 most of the boreal and mountainous coniferous forest areas of the 

 continent north of Mexico. There is no good evidence that the species 

 breeds south of the United States-Mexican border. Summer speci- 

 mens collected in the Sierra de la Laguna, Baja California, were 

 regarded by Brewster (1902) and Grinnell (1928) as indicating breed- 

 ing, but McCabe and McCabe (1932) and Banks (1967) seem to be 

 justified in considering them migrants or at most nonbreeding birds. 

 In migration, hermit thrushes move southward and spread out to 

 winter over most of the southern portion of the United States and 

 through Mexico to Guatemala. 



The hermit thrush breeds in all or part of seven major ecological 

 climax zones or "Life Areas" delineated by Aldrich (1963, p. 532). 

 These include all of the region characterized by the transcontinental 

 "Closed Boreal" forest from Newfoundland to northern British 

 Columbia and central Alaska, the more southern "Northern Hard- 

 wood-Conifer" area from Nova Scotia to Minnesota and southeastern 

 Manitoba, southward in the Appalachian Mountains to West Vir- 

 ginia, and the "Aspen Parkland" from central Manitoba and north- 

 western Minnesota west to central and central-southern Alberta. 

 The small breeding populations on Long Island, N.Y., and Cape 

 Cod, Mass., in the pine barrens section of the "Eastern Deciduous" 

 Life Area are probably relicts of a former more favorable ecological 

 situation. The hermit thrush breeds also, at least locally, in the more 

 northern, transcontinental "Open Boreal" forest area that extends 

 from Labrador to western Alaska. In the western part of the con- 

 tinent it nests in high mountain forest zones with climax vegetation 

 of a coniferous or mixed coniferous-deciduous life form, particularly 

 the "Closed Boreal" (subalpine) and "Montane Woodland-Brush," 

 from interior British Columbia south to southern California, Ari- 

 zona, New Mexico, and extreme western Texas. Along the Pacific 

 coast it breeds in the lowland and coastal mountain "Pacific Ram 

 Forest" zone from California northward to the coast of southern 

 Alaska and westward to the base of the Alaska Peninsula and Kodiak 

 Island. Westward on the Alaska Peninsula it nests in alders beyond 

 the limit of large trees in the "Arctic- Alpine" area (Murie, 1959). 



Within these geographically extensive "Life Areas," each charac- 

 terized by a single ecological climax type, the hermit thrush nests 



