loo? ] Cameron, Birds of Custer & Dawson Counties, Mont. 397 



how numbers of previously unseen Cowbirds would suddenly appear from 

 space to perch upon him and run up and down on his back. Horses are 

 corralled here which are covered with Cowbird excrement, and on June 3, 

 1894, I drove up my saddle horses with seven Cowbirds perched on the 

 back of one of them. My neighbor, Mr. H. H. Tusler, has caught Cow- 

 birds on horses with his hands. 



In summer, when a bunch of cattle is driven to some outlying pasturage, 

 Cowbirds often follow the drove for the whole distance, alighting con- 

 stantly upon, or just in front of the animals. Many times it seems as if 

 the birds cannot avoid being trodden on, but they just manage to run out 

 of the way in time. Occasionally, the Cowbirds leave the cattle to dart 

 after flying locusts which they catch very cleverly with their bills. 



It would seem that Cowbirds sometimes attach themselves to particular 

 cattle, follow them wherever they wander, and drink when they go to 

 water. I noticed young Cowbirds, in August, 1905, which were insepa- 

 rable from certain cattle of mine for at least a week. Two of these birds 

 were quite buff in color with dusky streaks and easily distinguished. 



I have found Cowbird eggs in the nests of the Long-tailed Chat, Brewer's 

 Blackbird, Arctic Towhee, Vesper Sparrow, and Chipping Sparrow. I 

 have seen them more frequently in the nests of the latter than of other 

 species. Three Cowbird eggs are the most I have observed in any one nest. 

 On July 25, 1896, I saw the empty, deserted nest of a Chipping Sparrow 

 in a sage bush a foot from the ground. Underneath lay an egg of the 

 sparrow and one of a Cowbird. For an exhaustive account of the parasitic 

 nesting habits of the Cowbird in this region see Coues's 'Birds of the North- 

 west,' p. 181 et seq., 1874. 



111. Xanthocephalus xanthocephalus. Yellow-headed Blackbird. 

 — Tolerably common on migration, but the least numerous of the black- 

 birds which come here. Yellow-headed Blackbirds arrive about the first 

 week in May and have disappeared by the end of September. They are 

 also seen in the pine hills. Flocks which frequented the haymeadow, 

 haystacks, and corrals in the fall at my ranch in Custer County consisted 

 chiefly of immature birds. While the adult male presents such a splendid 

 appearance, the immature young also show striking variations of plumage. 

 One of these shot among other species of blackbirds in the corn on August 

 19, 1898, was colored as follows: The throat from the base of the bill was 

 bright yellow, which extended to the breast, this color being divided from 

 the chestnut sides of the head by a coal black patch under and including 

 the eye. The crown, hind neck, and all other parts were black except 

 some yellow feathers at the vent. The irides were hazel and the bird was 

 ten inches long. Yellow-headed Blackbirds nest at several localities in 

 Custer County. On June 17, 1905, my wife found these birds numerous 

 at Brackett's ranch on Whitney Creek, and was told that they were nest- 

 ing in the vicinity. 



112. Agelaius phceniceus arctolegus. 1 Red-winged Blackbird. — 



1 See Oberholser, Auk, Vol. XXIV/p. 332. 



