DESERT HORNED LARK 339 



They prefer the dry bench lands. There is no special preference as to surface 

 contour so long as the situation is a dry one. Nests occur on knolls or slopes, or 

 in the dry depressions of the benches. * * * The number of nests which one 

 finds near old dried droppings of horses, and sometimes of cattle, seems much 

 greater than the laws of chance would account for. ♦ * ♦ Only one nest was 

 found in a cultivated field. * * * It was in a field of young spring wheat 

 which stood in drills, about two inches tall, the ground being otherwise bare. 



* 4> * 



The nest is invariably built in a rounded hollow in the ground, which is evi- 

 dently scratched out by the birds, the excavated dirt in the form of fine scratch- 

 ings being thrown out to one side of the nest. The dirt is almost always on the 

 east side, which is also the side least protected by vegetation. Usually the top 

 of the nest structure is flush with the ground surface. * * ♦ The materials 

 used for the body of the nest are dead grasses, including both stems and blades, 

 usually without any other materials. 



The nest built on cultivated land contained rootlets and old dead 

 grass. The linings were more varied, including a bit of rag, some tiny 

 bits of rabbit fur, soft, silky, white plant down, and seed pods, heads, 

 tips, or leaves of yarrow, which when dried are gray or white and of 

 soft, velvety texture. 



"All nests examined, with only one exception, were provided with 

 pellets of dried mud at the entrance or elsewhere around the nest. 

 These are little cakes or broken pieces of the cracked crust which 

 forms on the surface of mud when baked by the sun. * * * xhe 

 pellets are used chiefly to cover the loose dirt thrown out in excavat- 

 ing the hole for the nest." 



The inside diameter of nine nests averaged 2.49 inches, and their 

 inside depth averaged 1.92 inches. The ground hollow for one nest 

 was 4 inches in diameter and 2 inches deep. The time required to 

 build the nest, after the hollow was dug, varied from 2 to 10 days. 

 As to concealment of the nests, he says : "The prevailing short grasses 

 of the bench lands do not afford much cover. The concealment of 

 nests in general, so far as the surrounding grass is concerned, is 

 very incomplete, sometimes quite meager. Nevertheless, the nests 

 are not easy to see. In most cases there is some protection from 

 grass on the west side; sometimes it slants over the nest, owing to 

 the prevailing winds." 



Eggs. — The desert horned larks usually lay three or four eggs, 

 perhaps very rarely five, though none of Mr. DuBois's 58 nests con- 

 tained five. These are practically indistinguishable from those of 

 the other races of similar size. Some sets are somewhat paler and 

 less heavily marked than those of the darker races. The measure- 

 ments of 50 eggs average 22.1 by 15.6 millimeters; the eggs showing 

 the four extremes measure 23.9 by 15.5, 23.4 by 17.0, 20.6 by 15.2, and 

 19.6 by 15.2 millimeters. 



