312 Uiiivcrsity of California Publications in Zoology [Vol. 16 



WATER-MARGIN HABITAT AND ASSOCIATION (PRAIRIE AREA) 



Exclusive : 



Chrysemys bellii. Aetitis macularius — summer. 



Grus mexicana — summer. 



Major: 



Eana pipiens brachyeephala. Agelaius phoenioeus neutralis — 

 Thamnophis elegans. summer. 



Anas platyrhynchos — winter. Prooyon psora paeifica. 



Nettion earolinense — winter. Mustela vison energumeuos. 



Ardea herodias treganzai — resident. Ondatra zibethica osoyoosensis. 



Oxyeehus voeiferus vociferus — Castor canadensis canadensis, 

 resident. 



Minor: 



Spatula clypeata — migrant. Eiparia riparia — summer. 



Streptoceryle alcyon caurina — Mephitis occidentalis major. 



resident. Peromyscus maniculatus gambelii. 



Reported : 



Baseanion constrictor vetustum. 



Along the smaller streams of the prairie are numerous small gravel 

 and dirt bars. These usually become very dry in summer and the 

 grasses and herbs growing on them dry up, except in a few places at 

 the level of the water or along the rare sloughs. 



Along Snake River there is a considerable width of water-margin 

 habitat, which is annually covered during the spring high water. 

 There are few willows or shrubs along this stream and the water-margin 

 habitat is broad except where cliffs reach the edge of the water. Near 

 the edge of the water plants are almost absent, only a few herbs being 

 found. On the higher level of the beach there is considerable drift- 

 wood and the ground is quite sandy. In among the logs the plants of 

 the bunchgrass habitat appear and so also do a number of weeds. 



The water-margin association of the prairie is chiefly made up of 

 species which feed along the shores of the streams. Kingfishers and 

 bank swallows are known to nest in holes in the soft dirt banks. 

 Robins gather mud for plastering their nests from along the shore. 

 A number of species from both cottonwood-willow and bunchgrass 

 associations probably come to the water's edge to drink. 



Twenty traps set among rocks and driftwood on the shore of Snake 

 River near Lyon's Ferry caught two Peromyscus maniculatus gambelii 

 on June 25, 1914. 



