WILDLIFE RESTORATION AND CONSERVATION 
 
The problem of lead poisoning in waterfowl could, of course, be 
solved by using a nontoxic metal, such as copper or iron, for shot 
pellets. The densities of these metals are far below that of lead. 
The use of either copper or iron would so change ballistics and de- 
crease shooting ranges that it is doubtful that shot made from these 
metals would be acceptable. It therefore appears that the problem 
must be solved by some modification in the use of lead. 
There appear to be three methods by which lead poisoning in ducks 
might possibly be prevented: First, the development and use of a 
nonpoisonous lead compound or alloy in which the nontoxic feature 
is due to chemical nature or physical combination; second, a lead 
alloy which would have a highly corrosible surface, so that lead shot 
in the gizzard would be ground away so rapidly that sufficient absorp- 
tion for poisoning would not occur; third, an alloy of lead which 
would disintegrate in natural waters and either be not available to 
feeding ducks or disintegrate rapidly in the gizzard, if eaten, and 
pass out so quickly that poisoning could not occur. 
It may be doubtful that the first method described can be realized, 
as the lead must be in metallic form to have the desired weight. The 
second method has the inherent weakness that, as the surface of par- 
ticles is ground off, the exposed new surface becomes smaller and the 
grinding and elimination process consequently slows down. It has 
seemed to us that the third method is the most logical point of 
attack, although further investigations might show that a high surface 
erosion may be developed to a satisfactory degree. 
We have studied the mechanics of gizzard action in ducks by the 
use of lead powder and X-ray pictures, and have determined that 
the gizzard will usually completely eliminate finely divided lead in 
2 or 3 days. Passage of finely divided lead through the intestine 
was found to be very rapid, the time required for lead to pass from 
the gizzard to the cloaca being only a few hours. Elimination of 
lead powder from the gizzard through the gastrointestinal tract was 
found not to be a continuous process but to be controlled, apparently, 
by gizzard activity. It appears that after a period of grinding the 
gizzard contracts, forcing ground material into the intestine. Some- 
times the contractures are so great as to force all grit up into the 
proventriculus and even into the lower esophagus. Occasionally 
upon relaxation of the gizzard, some of the grit and lead shot passes 
out into the intestine. 
We have found that a combination of lead with a small amount 
of magnesium produces an alloy which, within certain limits, will 
disintegrate in the presence of water. The rate of disintegration 
can be varied by the percentage of magnesium present. X-rays show 
that pieces of this alloy will disintegrate in the gizzard of ducks 
without causing the bird inconvenience, and that the alloy will begin 
passing from the gizzard as fine particles at once. Within 24 hours 
most of the alloy will have been eliminated, and usually all traces of 
lead will have disappeared from the duck within 3 days. 
In the lantern slides shown with this paper is depicted the dis- 
integration of magnesium-lead alloy in the gizzard of mallard ducks. 
These slides were prepared from I-rays taken after feeding pieces 
of alloy by the use of a tube. The first series shows a rapid dis- 
integration of alloy no. 9, containing 96 percent lead and 4 percent