384 BULLETESr 17 9, UNITED STATES NATIONAL MUSEUM 



This is the characteristic Swallow of the Cape Region, if not the only 

 representative of the Hirundinidae, excepting the Western Martin, which breeds 

 there regularly and plentifully. About La Paz and other places on or near the 

 coast it perhaps occurs only in winter, as Mr. Belding indicates, but Mr. Frazar 

 found it common on the Sierra de la Laguna in May and early June, and at 

 Triunfo and San Jos6 del Rancho in late June and July. On the summit of 

 La Laguna it was nesting late in May, and one was seen flying over the highest 

 peak of this mountain on December 2. 



J. S. Rowley writes to me: "Comondii was the only place we 

 encountered these little swallows at all abundantly, and here they 

 were rather common because of the creek running nearby and the 

 only surface water for miles." He found several nests here on May 

 1, 1933, "containing eggs in various stages of incubation. Sets of 

 two and three seemed more common, but one set of five was taken. 

 All the nests found were made of feathers and hair, and placed well 

 up in old woodpecker holes in the cardons [saguaros]." 



There is an interesting nest, with two eggs, of the San Lucas 

 swallow in the Thayer collection in Cambridge, taken by W. W. 

 Brown, Jr., at La Paz on May 31, 1908. It is reported to have been 

 placed "in a depression on the face of a cliff among the rocks." It 

 must have been in a rather large cavity that sloped downward at 

 the outer edge, for the base of the nest measures over 5 inches in 

 diameter at its widest part, while at the inner end of the cavity the 

 nest proper is only 2 inches high. The bulky base of the nest is 

 made of coarse weed stems and long, fine grasses, circularly and 

 firmly woven to hold the nest cup in place; the nest cup is neatly 

 and compactly woven of the finest grasses and fibers, and is lined 

 with black and white hair; there are no feathers anywhere in its 

 composition. The inner cup measures about 2 inches in diameter 

 and about 1 inch in depth. It is not only the most peculiar swallow's 

 nest that I have ever seen, but decidedly the neatest. 



The eggs are ovate, pure white, and have hardly any gloss. The 

 measurements of 9 eggs average 17.3 by 12.9 millimeters; the eggs 

 showing the four extremes measure 18.3 by 13.0, 16.8 by 13.5, 16.8 by 

 13.0, and 17.0 by 12.0 millimeters. 



IRIDOPROCNE BICOLOR (Vieillot) 



TREE SWALLOW 



Plates 55-57 



HABITS 



CONTBIBUTED BY WiNSOE MARBETT TTLER 



Spring. — The tree swallow is the earliest of the six swallows that 

 move up the Atlantic coast in spring on the way to their breeding 



