SUMMER BIRD-LIFE OF AN IRRIGATED PORTION OF 

 THE SAN JOAQUIN VAIXEY. 



AT I^os Banos, in the San Joaquin Vallev of California, the waters 

 of the San Joaquin River are used to flood vast areas to create 

 grazing land for cattle. The region is naturally dry and arid, 

 but irrigation soon transforms the desert into a series of creeks, ponds 

 and marshes. The desert plants are replaced by Sagittaria, Ranunculus, 

 tules and cat-tails, and the desert birds give way to a remarkable assem- 

 blage of water birds, whose local distribution is governed by the presence 

 or absence of water. 



Driving along a levee, which extends as far as the eye can reach, 

 the old and the new life is found to be separated only by the width of the 

 dike. On the left is a parched and sterile plain with Horned Larks, 

 Burrowing Owls, Jack-rabbits, Coyotes, Rattlesnakes and other char- 

 acteristic desert forms; while on the right is water and fertility, with 

 Ducks, Herons, Ibises, Coots, Stilts, Avocets and other aquatic species 

 in countless numbers. 



To the east the view stretches across the desert toward the distant 

 Sierras, where on clear days may be seen the snow fields, which, eighty 

 miles away, supply the water at one's feet. To the west (the view 

 represented in the group) one looks over green marshes and shining 

 ponds fairly twinkling with flitting wings, to yellow fields leading up 

 through molded brown foot hills to the crests of the Coast Range. 



The group contains only the commoner birds of the region. Black- 

 necked Stilts, Avocets, Killdeer, Black and Forster's Terns, Black- 

 •crowned Night Herons, White-faced Glossy Ibises, Coots, Mallards, 

 Pintails, Cinnamon Teals, Ruddy and Fulvous Tree Ducks. 



While it is true one would not find all these species in a space eight 

 by twenty feet, one could frequently see all or most of them in a single 

 glance, and the impression the group seeks to convey is therefore within 

 the truth. 



The sudden changes occasioned by the irregularity of the water 

 supply are often disastrous to the liirds nesting here. The homes of 

 birds which begin to nest before the water has reached its height are 

 sometimes flooded, while the withdrawal of the water deprives the birds 

 of its protection and makes their nests and eggs accessible to marauding 

 animals. 



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