330 BULLETIN 203, UNITED STATES NATIONAL MUSEUM 



Spring. — The main migration route of the cerulean warbler is 

 through the Mississippi Valley, from the AUeghenies westward; it 

 is rare in the Atlantic States, especially the more southern ones, and 

 hardly more than casual in Florida and the West Indies. It enters 

 the United States, in Texas and Louisiana, in April, and reaches its 

 breeding grounds in the interior early in May. 



Rathbun (MS.) says of the spring migration in central New York : 

 "The cerulean warbler arrives in this region about the middle of 

 May, its coming being announced by its song. With rare exceptions, 

 it is not found in the spring migration with other warblers and it ap- 

 pears to move in very small groups or singly ; even in the large spring- 

 time movements of warblers known as 'waves,' some of the birds of 

 which remain while others pass through the region, I have observed 

 very few cerulean warblers. Not much time elapses after its arrival 

 before mating takes place and nest building begins." 



Nesting. — The earlier ornithologists knew nothing about the nest- 

 ing habits of the cerulean warbler ; Audubon's description of its nest 

 was entirely erroneous, and it was about 50 years after the bird was 

 discovered that its nest was reported. This is not strange, as the 

 nest is not easy to find and still more difficult to secure. Rathbun 

 (MS.) writes in his notes: "During our stay in New York State, we 

 found only three of its nests, because they were rather difficult to 

 locate. We found the first at a height of 55 feet in a little cluster 

 of small, twig-like branches growing on the side of a feathered elm ; 

 these clusters were close enough together to be of great use in climbing 

 the tree, which was at least 3 feet in diameter. The nest was dis- 

 covered by seeing the bird fly into the cluster. Within the next week 

 a second nest was found by watching the female bird; it was at a 

 height of 45 feet in a very small, flat crotch of a soft maple. The 

 third nest was at a height of about 30 feet. 



"The nests were identical in all respects except as to shape, which 

 varied because of its situation. Each was nicely made but not un- 

 usual in appearance. The material used was almost wholly the fine 

 strips of the grayish bark of small weed stalks, neatly interwoven. 

 Each was smoothly and beautifully lined with the fresh stems of 

 ground mosses of a brownish red color, which contrasted nicely with 

 the gray outer material. Of great interest was the smoothness with 

 which the material was woven in." 



Burtch wrote to Dr. Chapman (1907) that near Branchport, N. Y., 

 where the bird is locally common, "the nest is usually placed on a 

 horizontal branch or drooping branch of an elm, ranging from twenty- 

 five to sixty feet from the ground, and from four, to fifteen, or eighteen 

 feet from the body of the tree over an opening.'''' 



W. E. Saunders (1900) reports eight nests found in southern 

 Ontario ; two of these were in oaks, 20 and 23 feet up, two in maples. 



