BIRDS OF NEW YORK 349 



Iridoprocne bicolor (Vieillot) 

 Tree Siva How 



Plate 88 



Hirundo bicolor Vieillot. Ois. Amer. Sept. 1807 (1808). 1:61, pi. 31 



DeKay. Zool. N. Y. 1844. pt 2, p. 38, fig;. 63 

 Iridoprocne bicolor A. O. U. Check List. Ed. 3. 1910. p. 293. No. 614 

 iridoprocne, from Gr., meaning iris or rainbow-swallow; bicolor, Lat., two colored 



Description. Upper parts steel blue with a greenish sheen; under parts 

 white; tail sHghtly forked. Immatiire have the upper parts brownish gray. 

 Length 6 inches; extent 13; wing 4.5-5; tail 2.5. 



Distribution. This species inhabits North America as far north as 

 Labrador and Alaska. In New York it is found in all portions of the 

 State, but is much less common and more local in distribution as a summer 

 resident in the southern counties. It prefers the vicinity of water; and 

 in localities like river valleys, extensive marshlands, the flooded swamps 

 of the central lake region and the Adirondack lakes, it is the commonest 

 swallow. In the fall it sometimes appears in myriads along the coast, 

 the shores of the Great Lakes, and the Montezuma marshes, as well as 

 the large river valleys. I have seen tens of thousands gathered to roost 

 each night in portions of the Montezuma marsh and on the marshes along 

 the shore of Lake Ontario. It is the earliest of all our swallows to migrate, 

 appearing in western New York from the 27th of March to the loth of 

 April, average date April i, in the Atlantic district occasionally arriving 

 as early as the i6th of February or from the ist to the 21st of March. 

 In the fall it disappears from western New York from the loth to the 20th 

 of October, in the coastal district occasionally remaining to the ist of 

 November. 



Haunts and habits. The Tree or White-breasted swallow breeds in 

 hollow trees, the deserted holes of woodpeckers and in boxes which are 

 erected for its accommodation. In western New York, however, it does 

 not avail itself so readily of nesting boxes as is reported from the Hudson 

 valley and from the New England States. I have no doubt that if boxes 



