340 BULLETIN 179, UNITED STATES NATIONAL MUSEUM 



Young. — In his second paper (1936) Mr. DuBois gives a full ac- 

 count of the developments of young desert horned larks, to which 

 the reader is referred for details, as only portions can be quoted here. 

 He writes: "Apparently the male never assists in the duty of incu- 

 bation, but both parents take part in feeding the young as soon as 

 the eggs have hatched. The food for the young is evidently of a 

 solid nature from the beginning. A parent was observed carrying 

 a smooth green caterpillar in the afternoon of the day of hatching. 

 Large larval insects are fed to the young birds after they are strong 

 of flight. Parent birds were seen carrying excreta away from the 

 nest when the nestlings were two and three days old." He tells of 

 the hatching of a chick from an egg held in his hand : 



When It was ten hours old, nearly all of its natal down was dry, fully 

 three-eighths of an inch long, and very fiuffy — a marvelous transform- 

 ation ! * * * At the age of seven or eight days the nestlings are fairly 

 well feathered and the natal down is confined to the feather tips. * * * 

 When ten days old the young have left or are, in most cases, leaving the nest. 

 They are not able to fly but can run very well. It appears that they usually 

 leave in the fore part of the day. * * * It is easy to identify the horned 

 lark nestlings, at any stage of their development, by looking into their mouths. 

 The mouth lining is orange, and there are distinct black marks in the mouth 

 and on the tongue. This distinguishes them at once from the nestlings of 

 McCown and Chestnut-collared longspurs, which have plain pink mouths and 

 throat linings. When the young larks have grown up, the orange color fades 

 and the black marks disappear. 



Leon Kelso (1931) also gives a detailed account of the development 

 of the young in four nests of this lark, to which the reader is referred. 

 He states: "It is evident that the rate of growth and length of 

 time spent in the nest by nestling Desert Horned Larks varies accord- 

 ing to the time of the year. The young of nests 1 and 4, in the 

 months of April and May, respectively, remained in the nest at 

 least ten days, while those of 2 and 3, in July, stayed in the nest not 

 more than 7 days. The size attained appeared to be comparable in 

 all instances. * * * The first nest has a lining of thistle-down, 

 contained 1505 pieces of material and weighed 16.75 grams; the 

 second had no lining, was built of 805 pieces, and weighed 7.7 grams." 



EneTnies. — Mr. DuBois (1936) writes: 



On their nesting grounds the Desert Horned Larks have to contend with their 

 share of enemies and sources of accident. Among the natural enemies, weasels, 

 skunks and ground squirrels came to my attention, not to mention man, whose 

 poisoned baits set out for ground squirrels apparently kill more birds than 

 spermophiles. One day, by quick action, I intercepted a weasel on his way to a 

 nest to get the last nestling. The birds, of course, are powerless to defend 

 their young against weasels and skunks. It is believed that the abundant ground 

 squirrels often destroy eggs, and possibly sometimes take a nestling ; but the adult 

 larks are not afraid of them. It is common to see the larks driving a trespassing 



