4 BULLETIN 793^ V. S. DEPAETMENT OF AGRICULTURE. 



breast, and in a very short time tlie birds are unable to fly. (PL I, 

 figs. 1 and 2.) Following this the wings begin to droop from the 

 sides. In many cases the extensor muscles supporting the wing tip, 

 that portion of the fore limb homologous with the hand, are seriously 

 affected, and the wing hangs from the carpal joint, a symptom 

 strikingly like the " wrist drop " found in many cases of lead poison- 

 ing in man. The wings float loosely on the surface when the affected 

 birds are in the water, and in severe cases the tips of the primaries 

 may drag as the bird walks about on the ground. Other muscles are 

 affected as well. When the bird is standing, the breast is depressed 

 and the tail droops. (PI. II, fig. 2.) 



After a few days birds often experience difficulty in walking and 

 may fall as they attempt to turn around. This paralysis of the legs 

 grows until the body can no longer be supported, and in moving 

 about the birds slide along on the breast. (PL I, figs. 1 and 2.) 

 This loss of function in the muscles is not always symmetrical; in 

 several cases muscles on the left side were more severely affected than 

 on the right. This was especially noted in the leg muscles. In many 

 of the living birds studied the poisoning due to ingested shot wa« 

 acute, and death came in a few days. In others the condition be-^ 

 came chronic, and the birds, much emaciated, lived from two to five 

 weeks. Often an adult mallard would waste away until the large 

 muscle masses of the breast were reduced to slender fasciae that were 

 barely sufficient to cover the sternum. 



The feces of affected birds are thin and watery and stained green. 

 This color is a well-marked symptom. Wlien fecal matter comes 

 largely from the rectum the green is very dark, but when mixed with 

 renal matter in the cloaca it becomes paler. In this^ case the green 

 color, though lighter, is remarkable for its brightness. The body 

 temperature of affected birds is normal, unless the individual is 

 anaemic, when it is subnonnal. 



In weak birds the eye was usually very bright and the muscle con- 

 trolling the nictitating membrane not affected. During field work in 

 Utah this point was used as a ready means of distinguishing these 

 birds from individuals helpless from poisoning due to alkalies.^ 



The heart of a bird suffering from lead poisoning is affected, and 

 the bird may die suddenly after fright or exertion. Captives under 

 observation were liable to spasms after they had become much weak- 

 ened, during which they fell on the breast with head and wings ex- 

 tended, and were agitated by slight but rapid tremors. In some 

 cases this caused the lower mandible to rattle against the upper. 

 These spasms were followed by periods of wealaiess, when for a time 

 the birds lay motionless, but later were able again to walk about. The 



1 Cf. Wetmore, Alexander. The Duck Sickness in Utah : Bull. 672, U. S. Dept. Agr., 

 pp. 1-25, 1918. 



