THE DUCK SICKNESS IN UTAH. 7 



on in the Bear River region until October 28. Lake Bowdoin, near 

 Malta, Mont., where sick ducks had been reported, was visited from 

 October 2 to 9. On August 25 the lakes and marshes west of Salt 

 Lake City were inspected in company with J. C. Smith, of the State 

 Fish and Game Commission. In October one visit was made to 

 Promontory Point. 



In 1916 the field laboratory on Bear River was opened on May I 5. 

 Experimental work begun in the previous years .was carried on to 

 completion, and a large number of birds were handled and studied. 

 The Locomotive Springs marsh near Kelton was visited on August 

 29. Work terminated on Bear River on October 25. 



Acknowledgments are due many organizations and individuals for 

 kindly assistance rendered in many ways, without which the in- 

 vestigation could not have proceeded nor could much valuable 

 information have been secured. 1 The Bureau of Chemistry has 

 cooperated in making analyses of water, alkaline scale, and other 



material. 



THE DUCK SICKNESS. 



SYMPTOMS AND DESCRIPTION. 



The symptoms of the duck sickness in large part indicate a paralysis 

 of the nerve centers controlling the muscular system. In exercising 

 their powers of flight birds exert a maximum amount of energy, 

 and a decrease in these activities is one of the early indications of 

 the duck sickness. Birds affected may be able to support themselves 

 in the air for short distances only, or may have the wings entirely 

 helpless. Between these two stages all intermediate conditions are 

 found. The paralysis is most marked at first in the great pectoral 

 muscles that direct the wing in its downward stroke. The smaller 

 muscles that support the wing when folded also relax and allow the 

 carpal joint to drop from its normal position, so that the wings in 

 birds at rest droop from the sides of the body (PL II, fig. 2). In 

 swimming the anterior wing joint drags in the water, often forcing 

 the wing tips up conspicuously at an angle above the back. 



With this affection of the wings the paralysis gradually spreads 

 to the muscles of the legs. Birds become unable to support the body, 

 though still able to swim. Some individuals, though apparently 

 helpless, are able to make off at a great rate by aid of both wings 

 and legs. In individuals of species that have the legs greatly de- 

 veloped and specialized, as the avocet and the black-necked stilt. 



i Especial thanks are due to the officers of the Duckville Gun Club for living quarters in the clubhouse 

 and to individual members for assistance in field work; to the Bear River Club for permission to use a 

 tract of ground utilized in experimental work, and other facilities; to A. P. Bigelow, of Ogden, Secretary 

 of the Bear River Club Co., for aid in many ways; to L. B. McCornick for valuable assistance: to 

 V. F. Davis, superintendent of grounds of the Bear RiverClub, for information of value: to Clarence Adney, 

 of Corinne, for assistance; to W. O. Belnap for aid in work at the mouth of the Weber River: to the New 

 State Gun Club for quarters while working on the Jordan River marshes: and to the State fish and game 

 commissioner for permits for shooting and handling birds as needed in the work. 



