16 BULLETIN 936, U. S. DEPARTMENT OF AGRICULTURE. 



OTHER CONDITIONS AFFECTING WATERFOWL. 



AGRICULTURAL OPERATIONS. 



It has been said in the foregoing that the supplies of seeds car- 

 ried over winter in the fruiting heads of the bayonet grass, or tule, 

 are of importance as food for the wild ducks returning from the 

 South in spring. As these seeds are available practically through- 

 out the year they furnish a valuable source of sustenance. The 

 burning of large areas, therefore, to clear the marsh, or to induce 

 a fresh clean growth for ranging purposes is to be frowned upon, 

 as it tends to destroy a certain proportion of the available stock of 

 duck food. Many of the seeds are charred and destroyed by the 

 flames, and though a part are not seriously harmed a large propor- 

 tion of the stock is liable to be washed away and lost during the 

 high water incident to the breaking up of the winter covering of 

 ice in spring, and the subsequent floods due to melting snows in 

 the foothills. While the practice of burning clears the marsh, it 

 also destroys mats and tangles of dead vegetation that in many 

 cases form necessary, shelters for the breeding ducks, insuring the 

 successful hiding of their nests and later protecting the young until 

 they are strong enough to venture into the open. 



A practice that is almost equally injurious is that of mowing cer- 

 tain areas along the banks of the river and the larger overflows in 

 order to put up wild hay. It is of course unavoidable that many 

 ducks' nests are destroyed in the alfalfa and hay fields in the up- 

 lands, as these areas produce valuable crops. Where Bear Eiver 

 breaks up into overflows near its mouth there is a narrow band of 

 sweet clover, salt grass, and foxtail along the banks that is some-, 

 times harvested with mowing machines. Where this is done before 

 July 20, a considerable' number of ducks' nests are uncovered or 

 destroyed, and in some cases the ducks themselves are maimed or 

 killed. Xests exposed in the open are in a majority of cases rifled 

 by magpies, coyotes, or other enemies- and so are destroyed. The 

 cinnamon teal and gadwall nest commonly in these areas, and in 

 this way are injured frequently. Where mowing is necessary it 

 should be done after July 20, if possible, and in any case the vege- 

 tation bordering the channels should be left untouched. Compara- 

 tively few of the ducks that nest here locate their nests farther 

 than 100 feet from the water's edge, and by mowing outside this 

 limit only an occasional brood will be destroyed. 



NATURAL ENEMIES. 



Magpies. — The ducks in the area under consideration are not with- 

 out natural enemies. Among these the magpie is perhaps the most 

 common, though it is restricted in its range to the immediate vi- 

 cinity of the narrow band of willows that lines the river bank and 



