112 Wyoming Experiment Station. 



while 94 contained nothing but weed seed. The amount of 

 weed seed destroyed by birds in a single year in the United 

 States is immense, and it is evident that the cowbird is one 

 of the noteworthy agents by which the already overflowing 

 tide of noxious weeds is kept within its present limits. 



"In summing up the results of the investigation, the fol- 

 lowing points may be considered as fairly established : ( i ) 

 Twenty per cent of the cowbird's food consists of insects, which 

 are either harmful or annoying. (2) Sixteen per cent is grain, 

 the consumption of which may be considered a loss, though it 

 is practically certain that half of this is waste. (3) More 

 than 50 per cent consists of the seeds of noxious weeds, whose 

 destruction is a positive benefit to the farmer. (4) Fruit 

 is practically not eaten. 



"In view of the fact that so much has been said in con- 

 demnation of the cowbird's parasitic habits, it may not be out 

 of place to inquire whether this parasitism is necessarily as in- 

 jurious as has been claimed. When a single young cowbird 

 replaces a brood of four other birds, each of which has food 

 habits as good as its own, there is, of course, a distinct loss ; 

 but, as already shown, the cowbird must be rated high in the 

 economic scale on account of its food habits, and it must be 

 remembered that in most cases the birds destroyed are much 

 smaller than the intruder, and so of less effect in their feed- 

 ing, and that two or three cowbird eggs are often deposited 

 in one nest." 



The records of this bird in Wyoming are fairly abund- 

 ant. Drexel found them at Fort Bridger, 1858; Wood took 

 some specimens on Pole creek; 1856; Williston has published 

 the following note from Lake Como : "a pair was seen among 

 the Brewer's Blackbirds May 12th, but I did not find them at all 

 common afterward ;" Gilmore has noted them in the Freeze- 

 out hills ; Coues reports them from La Bonte creek ; Jesurun 

 finds them common at Douglas ; Bond rather common at Chey- 

 enne. I have noted them at Sundance, Buffalo, Bonanza, Lan- 

 der, Casper, Ferris and on the Laramie plains. 



