No. 612] SHORTER ARTICLES AND DISCUSSION 755 



to feed at some favorable locality in the lake. Later in October 

 the other ducks were joined by American goldeneyes, Clmignlu 

 c. americana Bonaparte, while from observations it was certain 

 that the green-winged teal, Nettion caroUnense (Gmelin), at 

 times fed upon this same food. The number of crustaceans and 

 fly larvge destroyed by these birds must be enormous. 



In addition to these ducks great flocks containing thousands of 

 Wilson's phalaropes, Steganopus tricolor Vieillot, and northern 

 phalaropes, Lohipes lobaiics (Linnjeus), are found on the salt 

 water during migrations, where these birds likewise feed upon 

 the brine shrimp and the fly larvae and pupro. During October 

 and November flocks of eared grebes, Colymhns nigrkollis call- 

 f amicus (Heermann), were found on the lake along the cut-off 

 where their food must have been taken from the same supply as 

 none other suitable is found. It may be mentioned here that a 

 considerable number of shovelers and many thousand eared 

 grebes winter on Owen 's Lake in California, where saline condi- 

 tions are similar to those in Great Salt Lake, and where a simi- 

 lar fauna is found. 



Avocets, Recurvirostra americmm Gmelin, and black-necked 

 stilts, Himantopus mexicanus (Miiller), also fed upon Artemia 

 and Ephydra at the mouth of Bear River, and no doubt these 

 animals furnished food to other shore birds. Definite data on 

 this point is not at hand, however, as all of the shore bird 

 stomachs collected there have not yet been examined. It is 

 probable that the ring-billed gull, Larus delawarensis Ord, and 

 California gull, Larus calif ornicus Lawrence, also take this same 

 food at times. 



From the facts outlined above it will be seen that the toll 

 taken by birds from the brine shrimp and alkali fly larvie and 

 pupas during the course of a season constitutes a mass of indi- 

 viduals almost beyond comprehension. The digestion of food 

 by the birds concerned is always a rapid process, and with soft- 

 bodied animals like the brine shrimp a considerable mass would 

 be consumed each day ; and the same is true of the larvae and 

 pupae of the alkali flies. The immense number of these creatures 

 in the waters of the lake must be attributed to the large number 

 of offspring produced rather than to an absence of enemies. 



Alexander Wetmore. 



Biological Survey, Washington, D. C. 



