LEAD POISONING IN WATERFOWL. / 
entire liver. This was noticed in particular in examining several 
whistling swans received at the Washington laboratory from Back 
Bay, Va. 
RESULTS OF EXPERIMENTAL WORK. 
During the field seasons of 1915 and 1916 a series of experiments 
dealing with lead poisoning in ducks was made at a field laboratory 
near the mouth of Bear River, Utah. Though shot had been found 
in many instances in the stomachs of birds, their presence had not 
been determined absolutely as the causative factors of the disease 
apparent in such individuals. The stomachs of a large number of 
ducks have been examined in the laboratories of the Biological Sur- 
vey to determine the food habits of the species. These stomachs 
were from birds apparently healthy when killed. It is not unusual 
to find from one to half a dozen or more shot pellets in such stom- 
achs, and in birds from certain localities pellets were almost always 
found. These facts cast some doubt on the supposition that ducks 
were affected unfavorably by eating shot, and it was necessary to test 
the matter by actual experiment. 
For this purpose small pens 3 feet wide, 3 feet high, and 5 or '6 
feet long were used. Each pen was placed on a platform a foot 
above the ground with a hole cut in one end to hold a water pan, and 
the boards were covered with earth. Ducks were taken from large 
stock pens and placed in these smaller pens as needed, while control 
birds were confined under similar conditions in separate pens. They 
were fed morning and evening on mixed grain containing wheat and 
barley in equal quantity. 
Wild mallards, captured when young and reared to maturity, were 
used in the main experiments, so that there was no possibility of 
their having obtained shot before they were placed under close obser- 
vation. Shot and lead were given to these birds through a small 
glass funnel. The lower end of the funnel was placed well down the 
duck's throat and after the shot were given a small quantity of water 
was poured down to insure that the pellets or particles should not 
lodge in the oesophagus. After treatment birds were watched closely 
for several minutes to make certain that none of the lead was cast 
out through the mouth. It was found that six pellets of No. 6 shot 
constituted an amount of lead that was always fatal. Two or three 
shot were sufficient to cause death in several instances, and as the 
number was increased the resistance of individual birds decreased. 
In one experiment two mallards were each given one No. 6 shot. One 
died 9 days later, while the other was able to throw off the effects of 
the lead and recover. Pintails and redheads were similarly affected. 
One male pintail was given four pellets of No. 6 and another six. 
