2 BULLETIN 672, U. S. DEPARTMENT OF AGRICULTURE. 
study. Agents of that bureau also made investigations in the field. 
In order to determine, if possible, the cause of the mortality, a short 
preliminary examination of the affected areas was made in August, 
1913, by an assistant from the Biological Survey, and in the follow- 
ing year work was begun in July and continued during the summer 
and fall of 1915 and 1916. A prehminary report covering the work 
of the first year was published in the spring of 1915. 1 The present 
bulletin covers the entire investigation in so far as is pertinent to 
a discussion of the conclusions reached. 
HISTORY IN UTAH. 
Sick ducks had been noticed in the Bear River marshes at the 
northern end of Great Salt Lake for many years, though the trouble 
is not known to have been serious until 1910. The fact that there 
were sick ducks previous to the severe outbreak in that year was 
not generally known, some overlooking it and others refusing to ad- 
mit it. It is well established, however, that sick birds were present 
in small numbers. Several hunters and guides who have shot on 
these marshes for many hunting seasons have recalled that sick and 
dead birds were found at an early day. Twenty-five years ago the 
hunting season began on September 1, and in certain areas, as in 
the region known as the North Shore, it was not unusual to find 
many dead ducks on this date. Occasionally, sick birds were found 
and in some cases the rushes were full of decaying bodies. These, 
however, apparently attracted little attention. Some of the early 
settlers in this region have reported sick birds at earlier dates. 
A few ducks are known to have died on the New State Gun Club 
grounds at the mouth of the Jordan River in 1902 or 1903, and sick 
birds were first reported from the mouth of the Weber River at 
about the same time. Helpless teal, found on several occasions dur- 
ing 1904 in the tules on the Weber River marshes, near the North 
Shore Gun Club, caused comment among the hunters. There are 
no records of sick birds during the next four years, but in the sum- 
mer of 1909 a few were found in the Jordan River marshes, and 
late in fall others were reported. These late fall birds, found when 
ice was closing the marshes, may ha^e been affected with some other 
trouble. Many hunters considered them to be cripples that had es- 
caped during the shooting season. It is said that a considerable 
number of sick birds were found during that summer on the Weber. 
It was not until 1910 that attention was definitely directed to the 
duck sickness. The summer season of that year was dry and the 
water level of the rivers far below normal. In mid- July reports 
were current of a peculiar disease among wild ducks in the marshes 
1 Wetmore, Alex., Mortality among Waterfowl arouad Great Salt Lake, Utah; U. S. Dept. Agr. Bui. 
217, pp. 1-10, pis. 3, 1915. 
