16 BULLETIN 936, U. S. DEPARTMENT OE 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 
clucks' nests are destroyed in the alfalfa and hay fields in the up- 
lands, as these areas produce valuable crops. Where Bear River 
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. Nests 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 
