6 BULLETIN 672, U. S. DEPARTMENT OF AGRICULTURE. 



and many ducks. A few birds were still affected after the 1st of 

 October. Individuals examined at this time had the same malady 

 as the ducks in Utah, but it can not be stated definitely that all had 

 died from this trouble. 



Sick birds in large numbers were reported in the Cheyenne Bottoms, 

 near Great Bend, Kans., in 1914 and 1915. From information fur- 

 nished by Dr. N. P. Sherwood and Dr. B. T. Clawson, of the University 

 of Kansas, it would seem that these may have been suffering from 

 some bacterial affection. 



Other reports more or less indefinite have come from other regions 



in the West. 



OUTLINE OF FIELD WORK. 



A preliminary examination and study of conditions was begun by 

 the writer in the Salt Lake Valley on July 12, 1914, and continued 

 without interruption until October 30. Conditions on the Bear, 

 Weber, and Jordan Rivers were studied thoroughly, and visits were 

 made to the Willard Spur, Promontory Point at the southern end of 

 the Promontory Range, and Locomotive Springs, a large isolated 

 marsh area on the northern shore line of Great Salt Lake near Kelton. 

 In connection with this work the writer visited the Tulare Lake basin, 

 in California, from November 3 to 11, where he was assisted materially 

 by Tipton Matthews, deputy warden of Kern County, whose services 

 were made available through cooperation of the California Fish and 

 Game Commission. Following this, conditions were studied at 

 Owens Lake, Cal., from November 12 to 14. 



In 1915 work was begun in Utah on May 15 and continued until 

 October 25. As the investigations of the previous year had estab- 

 lished that the affection was apparently identical in the three large 

 areas involved, it was decided to carry on intensive work in one area 

 and to visit the other regions when necessary. The marshes and 

 shallow bays in the delta of Bear River at the northern end of Great 

 Salt Lake, offered a great expanse in which conditions were varied 

 and in which waterfowl were enormously abundant. A small tem- 

 porary field laboratory was erected here, and pens and cages for use 

 in experimental work were built as needed (PI. IV, fig. 2). This year 

 was unusually dry, and large areas were bare which were covered 

 with water under normal conditions. The New State Gun Club 

 marshes were drained by order of the club authorities early in the 

 year and remained dry during the whole summer season. The entire 

 volume of water in the lower part of the Weber River was taken out 

 for irrigation, and the flats at its mouth were dry until fall. On Bear 

 River the amount of water in the stream was greatly reduced, and 

 large marsh areas, normally covered with from 1 to 10 inches of water, 

 dried and baked in the sun. North Bay was dry, but a part of South 

 Bay remained, and here many ducks congregated. Work was carried 



