Io8 Loomis>« Birds of Chester County, South Carolina. \ x^tA 



mountain system perhaps giving the trend to the movement. 

 The wandering of solitary Owls far south is not significant, the 

 very fact of their being alone proving that they are stragglers. 



The Evening Grosbeak presents peculiar conditions. It is a 

 northern bird of southeasterly migration, and of erratic occur- 

 rence in the more southern and eastern portions of its winter 

 range. Its uncertain visitations seem to be due more to extension 

 of migration southward than to variation in lines of movement. 

 The more local irregularities, however, may be due to such 

 variability in location of isolated communities. The Great Plains 

 on the south and the Barren Grounds and Hudson Bay on the 

 north seem to give naturally a southeasterly trend to its migra- 

 tion. If the northern boundary of the strip of territory outlined 

 be continued eastward the New England States would fall largely 

 to the southward of it and would be in the path of a migratory 

 movement following its general course. The Great Lakes, too, 

 would appear to exert a deflecting influence. As southeasterly 

 migration exists in Brewer's Blackbird, Leconte's Sparrow, etc., 

 it is not an extraordinary circumstance that it should exist in this 

 species also. As in the Snowy Owl, protraction of migration is 

 attributed to shortness in food in the usual winter quarters. Its 

 later stay is probably due to the different character of its food, the 

 failure being more complete, and to its shorter fly-line, a smaller 

 subsistence area being drawn from. 1 



The winter migratory movements have been attributed to cov- 

 ering up of the food-supply by snow and ice, and the autumn 

 movements coincident with descent of temperature, as in the 

 Mockingbird, have been explained as anticipatory of failure of 

 food that would arise from over-population, owing to the 

 presence of birds from further north. The movements of June, 

 July, and August in this locality are obviously not occasioned by 

 present failure of food, for migrants find subsistence long after 

 the departure of breeding birds of the same species and often, 

 too, in far greater numbers. These summer movements it is 



1 In the Western Evening Grosbeak, Pine Grosbeak, White-winged Crossbill, 

 Redpoll, and Bohemian Waxwing it has not been determined, through want of precise 

 data, to what extent irregular movements may be imputed to mere variability in loca- 

 tion of isolated communities and to what extent to variability arising from protraction 

 of migration. 



