58 U.S. NATIONAL MUSEUM BULLETIN 233 



W. J. Sheffler informed me that he had noted many instances of 

 cowbird parasitism on this flycatcher in Arizona. Hanna (1936, p. 

 174) recorded two parasitized nests from Coachella Valley, Riverside 

 County, California. 



Horned Lark 



Eremophila alpestris (Linnaeus) 



The horned lark is an infrequent victim of the brown-headed 

 cowbird, but at least three of the lark's geographic forms are known 

 to have been imposed upon by the parasite — enthymia, practicola, and 

 leucolaema. Two races of the cowbird, ater and artemisiae. are 

 involved. Of the race enthymia there is one record — a parasitized 

 nest found at Cypress HiUs, Saskatchewan, June 8, 1920, by S. J. 

 Darcus. Of leucolaema there are two records — one found in Alberta 

 by T. E. Randall and one from Fergus County, Montana, reported 

 by W. Raine (1894, p. 120). The subspecies practicola is the only 

 one for which there are a fair number of records — 14 definite ones 

 and an indefinite number of others which are referred to loosely by 

 such statements as "locally commonly parasitized" around Grant 

 Park, lUinois (A. E. Price, in Htt.), or "I often find one or more 

 eggs of the cowbird in the nests of this species" in Marshall County, 

 Iowa (A. P. Godley, in Savage, 1895, p. 34). Although it can be 

 authenticated that in some places the horned lark is a fairly frequent 

 host, Pickwell (1931, pp. 106-109) found, out of 32 nests under obser- 

 vation in Illinois and New York, only one which was parasitized. 

 Moreover, in the annual nesting surveys of the Detroit Audubon Soci- 

 ety, numerous horned lark nests are reported each year but none have 

 been found which contain cowbird eggs or young. Price (1934, p. 

 107) noted two parasitized nests at Pajnie, Ohio, but he considered 

 it very unusual to find cowbirds' eggs in horned larks' nests. Wilhams 

 (1950, p. 153) fisted the prairie horned lark as a cowbird host in the 

 Cleveland, Ohio, region. Apparently, there must be considerable local 

 variation in the frequency of cowbird parasitism of this victim. The 

 above records come from southern Quebec, Ontario, Ohio, Illinois, 

 Iowa, Wisconsin, Kansas, and Minnesota. At Lake Crystal, Min- 

 nesota, Peabody (1899, p. 118) found 2 cowbird eggs in the same 

 nest of a horned lark; at Logan ville, Wisconsin, Robbins (1949) 

 reported a nest with 4 cowbird eggs and 2 of the host; all the other 

 records involved single eggs. 



Generally speaking, the cowbird does not lay to any extent lq nests 

 of the horned lark. Pickwell pointed out that, in lUinois and in some 

 other areas, more than half of the lark's breeding season is over before 

 that of the cowbird begins. He suggested that the early nesting 

 time, the exposed nature of the nest and the habitat, as well as the 

 early termination of the nestling period (10 days) may mitigate also 



