96 BIRD STUDIES WITH A CAMERA 
Five species are represented. Named in the or- 
der of their abundance they are the Tree, Bank, 
Barn, Eave, and Rough-winged Swallows. The last 
are comparatively rare, while the Tree Swallows are 
so in excess of all the species named that the follow- 
ing remarks relate largely to them alone. 
Although Tree or White-breasted Swallows nest 
locally throughout North America, from the table- 
land of Mexico to Labrador and Alaska, there are 
but few instances of their breeding in the lower 
Hudson River valley, where they appear only as 
migrants or transient visitants. They arrive from 
the south early in April, and their northward migra- 
tion is not concluded until about June Ist. During 
June they are rarely seen, but between the 1st and 
the 5th of July they begin their journey to their 
winter homes—a movement which inaugurates the 
fall migration. 
This stage of their journey takes them only to 
certain marshes, which become stations on their line 
of travel where countless numbers of their kind, 
impelled by the flocking impulse, gather to roost 
in the reeds. Their numbers increase steadily 
through July and August, the maximum of abun- 
dance being reached about September Ist; then they 
gradually become less numerous, and by October 10th 
comparatively few remain, though if the weather be 
favorable, they may be observed daily until late in 
the month. 
Throughout this period—from July to October— 
the marsh is used only as a dormitory, the reeds evi- 
dently offering suitable perches to these weak-footed 
birds, who in the morning radiate throughout the sur- 
