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 

 prehminary 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, ma} 7- have 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 around Great Salt Lake, Utah; U. S. Dept. Agr. Bui. 

 217, pp. 1-10, pis. 3, 1915. 



