The Birds of Wyoming. 35 



couple of acres in the ice on Hutton's lakes completely covered 

 with tKese ducks during the last week in March. They have 

 been taken at Hutton's lakes as late as January lo, 1896. The 

 University records are as follows : Green River, Buffalo and 

 the L,aramie Plains. Jesurun reports them common during 

 migration at Douglas, and Bond plentiful at Cheyenne. 



147. Aythya vallisneria (Wils.). 



Canvas-back. 



Migratory; rather uncommon. A few of this species are 

 usually found with the Red Heads. In Wyoming the}' are 

 more abundant in the fall than spring and are taken every 

 year by the hunters. Bond finds them rather common at Chey- 

 enne and Jesurun reports them common at Douglas. The 

 University records are Hutton's lakes and Lake DeSmet. 



148. Aythya marila (Linn.). 



American Scaup Duck. 



Migratory ; exceedinglv rare. There is no reason why 

 this bird should not be found more frequently. Up to the pres- 

 ent the only authentic record has been given by Jesurun of 

 Douglas and but a single bird has been taken. 



149. A3M:hya affinis (Eyt.). 



l-esser Scaup Duck, 

 Migratory ; common. Probably resident. They arrive on 

 the Laramie Plains as soon as the rivers are open and remain 

 for about a month, and are seldom seen on the lakes. Williston 

 reports them common and remaining all summer near Lake 

 Como; but cites no breeding records. Bond finds them com- 

 mon at Cheyenne and Jesurun the same at Douglas. The 

 University records all relate to specimens taken on the Laramie 

 Plains in the spring. 



150. Aythya coUaris (Donov.). 



Ring-necked Duck. 



Migratory; very rare. Coues reports one specimen taken 

 at Green River and Jesurun has taken one specimen at Doug- 

 las. 



