Page 109 - Our Vanishing Wild Life

DESTRUCTION BY DISEASES
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that the only method of discovering tlieir presence is by slitting the skin of the breast and paring it back a few inches when the worm-like sacs will be seen buried in the flesh. These parasites have come to my notice periodically during the process of skin- ning birds for mounting during the past number of years, but it was only when they appeared in unusual numbers last fall that I made inquiries of the biological bureaus of Washington and Ottawa for information of their life history and the possibilities of
their transmission to other hosts.
Replies from these sources surprised me with the information that very little was
known of the life history of any of the Sarcosporidia, of which group this was a species. Nothing was known of the method of infection or the transference from host to host or species to species, and both departments asked for specimens for examination.
Authorities are a unit in opinion that the question is one of great importance to game conservation, and although opinions of the dangers from eating differ somewhat, a record is given of a hog fed upon affected flesh developing parasites in the muscles in six weeks' time, while a case of a man's death from dropsy was found to be the result of development of these parasites in the valves of the heart.
The ability of these low forms of life to withstand extremes of heat makes it necessary for more than ordinary cooking to be assured of killing them, and since their presence is unnoted in the ordinary course of dressing the birds for the table, there is little doubt that very considerable numbers of these parasites are consumed at our tables every season, with results at present unknown to us.
The species I have found most particularly infected have been mallards, shovellers, teal, gadwall and pintails, and the birds, outwardly in the best condition, have fre- quently been found loaded with sacs of these parasites and only the turning back of the breast skin can disclose their presence.
The greatest slaughter of wild ducks by disease occured on Great SaltLake,Utah. Untilthe"duckdisease"(intestinalcoccidiosis)broke out there, in the summer of 1910, the annual market slaughter of ducks at the mouth of Bear River had been enormous. When at Salt Lake City in 1888 I made an effort to arouse the sportsmen whom I met to the necessity of a reform, btit my exhortations fell on deaf ears. Natu- rally, the sweeping away of the remaining ducks by disease would suggest a heaven-sent judgment upon the slaughterers were it not for the fact that the last state of the unfortunate ducks is if anything worse than the first.
On Oct. 17, 1911, the annual report of the chief of the Biological Sur- vey contained the following information on this subject
Epidemic Among Wild Ducks on Great Salt Lake.—Following a long dry season, which favored the rearing of a large number of wild ducks, but materially reduced the area of the feeding ponds, resulting in great overcrowding, a severe epidemic broke out about August 1, 1910, among the wild ducks about Great Salt Lake, Utah. Dead ducks could be counted by thousands along the shores and the disease raged unabated until late fall. Shooting clubs found it necessary to declare a closed season. Some of the dead ducks were forwarded to the Biological Survey and were turned over for examination to the Bureau of Animal Industry, by the experts of which the disease was diagnosed as intestinal coccidiosis.
Various plans of relieving the situation were tried. The irrigation ditches were closed, thus providing the sloughs and ponds with fresh water, and lime was sprinkled on the mud flats and duck trails. Great improvement followed this treatment, and experiments proved that ducks provided with abundant fresh water and clean food began to recover immediately. These methods promised success, but later it was proposed that the marshes be drained and exposed to the sun's rays—a course which cannot be recommended. That coccidia are not always killed by exposure to the sun isshownbytheirsurvivalonthesitesofoldchickenyards. Anaddeddisadvantageof the flan is that draining and drying the marshes would have a bad effect on the natural duck food, and upon the birds themselves.
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