MEXICAN CLIFF SWALLOW 485 



alike in size, the. only conspicuous difference being in the color of 

 the forehead. Mr. Ridgway calls this "fawn color, dull cinnamon, 

 or wood brown" in tachina, and "chestnut or cinnamon-rufous" in 

 melanogaste7\ 



The breeding range given for iachlna^ in the 1931 Check-list, is 

 "western Texas, the Rio Grande Valley, and through eastern Mexico 

 to Vera Cruz." 



The general habits of the lesser cliff swallow apparently do not 

 differ materially from those of the northern cliff swallow, except 

 that it seems more inclined to nest under primitive conditions, on 

 cliffs and canyon walls, and less inclined to nest on buildings than 

 the northern bird. 



The eggs of the lesser cliff swallow are similar to the eggs of the 

 other cliff swallows. The measurements of 58 eggs, reported by Col. 

 John E. Thayer (1915), average 20.2 by 13.7 millimeters; the eggs 

 showing the four extremes measure 23.1 by 14.5, 20.7 by 14.8, and 

 17.5 by 13.0 millimeters. 



PETROCHEUDON ALBIFRONS MELANOGASTER (Swainson) 



MEXICAN CLIFF SWALLOW 



HABITS 



The Mexican cliff swallow is readily separable from the northern 

 cliff swallow by its smaller size and by its "chestnut" or "cinnamon- 

 rufous" forehead and rump ; but it is very similar to the lesser cliff 

 swallow in size, and the latter is intermediate between the other two 

 races in the color of the forehead. The breeding range of the Mexican 

 cliff swallow extends from southern Arizona and southwestern New 

 Mexico southward over the Mexican tableland to Guatemala. 



Nesting. — While I was collecting with Frank C. Willard along the 

 San Pedro River in the vicinity of Fairbanks, Ariz., we visited the 

 home ranch of the Boquillas Cattle Co. to hunt for swallows' nests in 

 their large 2-story barn. We found a small colony of barn swallows 

 nesting on the joist braces over the carriageway in the lower story. 

 In the empty hayloft above a few Mexican cliff swallows were flying 

 in and out of the building, just beginning to construct their mud nests 

 on the rafters in the peak of the roof. At that date. May 17, 1922, 

 there were no completed nests of the cliff swallows, and most of the 

 barn swallows' nests held incomplete sets. Mr. Willard investigated 

 this colony later, of which he (1923a) says: "On June 9, in company 

 with Mr. Ed. C. Jacot, I again visited the colony and found that it 

 consisted of eight pairs. The birds looked out at us from each of the 

 six completed nests. Two nests were placed at the peak of the roof by 



?24726— 42 32 



