WILD DUCKS OF THE BEAE EIVEE MARSHES, UTAH. 17 
the shores of some of the larger overflows. The depredations of 
these birds are confined almost entirely to pilfering eggs from the 
nests, though occasionally they may kill newly hatched ducklings. 
In a' number of places the writer observed ducks* nests that had 
been broken up by magpies during 1915 and 1916. This was espe- 
cially the case with nests exposed during haying operations. There 
is no question that magpies, finding conditions here favorable to 
their- increase, have multiplied to a point where they are directly 
injurious to other more valuable species. It is a comparatively 
simple matter to limit their numbers by means of poisoned baits 
property used. Under proper conditions one man should be able 
to reduce them to the desired minimum in. two or three weeks' 
work. 4 It is neither necessary nor profitable to cslttj poisoning 
operations far enough to exterminate the birds, but merely to con- 
trol them to the point of eliminating a large part of the damage. 
Gulls. — Ring-billed and California gulls do not appear to harm the 
ducks during the breeding season, but during the fall kill a good 
many that are helpless with the duck sickness. Ravens do a certain 
amount of damage in the same way, but are not common enough to 
be considered definitely destructive. The case of the gulls is some- 
what different, as these birds are abundant and often are present in 
large flocks. During the shooting season gulls also attack ducks that 
have been killed by hunters and, not content with eating from one 
bird, often pick and tear open several, taking only a small portion of 
flesh from each. From observation it has developed that certain 
birds may become addicted to this practice, and it is an open ques- 
tion whether these individuals should be killed to prevent such un- 
warranted destruction. 
Other birds. — Among bird enemies that have not been mentioned 
are the duck hawks, which take occasional toll, and the black- 
crowned night heron, which at times eats young ducklings. The 
ducks destroyed by these two are, however, a negligible quantity 
and do not warrant the persecution of these birds. 
Coyotes. — The coyote is another enemy of the ducks and destroys 
a considerable number each year. In the delta region of the river 
these mammals occur during the summer, but do not become common 
until the middle of August or the first of September, at which time 
their tracks may be found in abundance. They work through the 
marshes in search of young ducks and "flappers" and also follow 
the borders of the bays to secure birds suffering from the duck sick- 
ness that has come into prominence here during recent years. 5 Many 
4 Those interested may obtain instructions for preparing properly poisoned baits by 
writing to the Biological Survey, Washington, D. C. 
5 Cf. Wetmore, Alexander, The Duck Sickness in Utah : U. S. Dept. Agr. Bull. 672, 
pp. 25, pis. 4, 1918. 
