?8o4 1 Loomis on Birds of Chester County, South Carolina. Ill 



ground. Vesper Sparrows and others became so famished that 

 children and dogs ran them down and captured them. That their 

 weakness was not due to cold, but to exhaustion from want of 

 food is shown by their enduring in other years, when there was 

 no snow, even greater cold without appai"ent discomfort. 

 Whether the birds that remained during the stress of weather 

 were migrants from the north that could get no further, or 

 whether they were winter residents whose previous experience, 

 be it personal, traditional, or inherited, had shown that snow was 

 of short duration in this region, is a matter undetermined. The 

 American Pipits, however, were prompt to go, as is their custom, 

 and there was partial migration early in other ground-inhabiting 

 species. Mr. Mackay mentions an instance (Auk, IX, pp. 334, 

 335) where Old-squaws on the Massachusetts coast perished from 

 lack of food owing to the prevalence of ice. 



While northward migration is held to be but a return-move- 

 ment, effected at the earliest moment, the conditions that prevent 

 migratory birds from remaining in the regions visited during their 

 migrations are not overlooked. Over-population and resultant 

 struggle for existence alone would preclude them from becoming 

 stationary in these regions. 1 This necessity for dispersion also 

 forces them to return to the region of their birth. That birds 

 should return to the same region to breed and winter is as neces- 

 sary as migration itself, for if there was no definite destination in 

 the majority of species there could be no uniformity of dispersal. 



As is well known, climatic conditions are potential influences 

 in distribution in the breeding season, the presence of boreal- 

 breeding birds far south on high mountains is a striking example. 

 Perhaps such conditions are equally potent in the migration of 

 some species, other regions than those where they breed being 

 unsuited to their needs. 2 Possibly concomitant alimentary con- 



1 In the South Temperate Zone, winter and migration from the south in indigenous 

 species would not only enforce the return of North American birds to their breeding 

 habitats, but would also prevent any void occurring through their departure. It is not 

 to be forgotten that there is some displacement at least of breeding birds by winter 

 birds in the tropics (antea, p. 10). 



2 Circumstances like the breeding of a pair of Myrtle Warblers in eastern Maryland 

 (Kumlien, B. N. O. C, V, p. 182), the overlapping of the breeding ranges of northern 

 and southern birds in mountains, and the wide-ranging in the breeding season of 

 species like the Yellow Warbler, create a doubt whether conditions arising from 



