Effects of DDT, Toxaphene, and Dieldrin on Pheasant Reproduction

AGRICULTURAL control chem{cals of h{gh tox{c{ty are being appl{ed in greater quantity every year. New chemicals are being developed and frequently appear on the market. Under these conditions, it is apparent that the potential hazard to wildlife species is increasing rapidly. Despite extensive studies carried on by the U. S. Fish and Wildlife Service and other agencies during the past decade, great gaps remain in our knowledge of chemical-wildlife relationships. One such gap is the effect of one or a series of chemicals on the reproductive capacity of an animal. Population declines may be brought about by an increase in the mortality rate or by a decline in the birth rate. A number of dead animals found in a treated area may indicate an increase in mortality, but the signs of a decrease in birth rate are far less obvious. Despite the lack of clear evidence for reproductive suppression under field conditions, experimental work with the fowl (Rubin et al., 1947) strongly suggests that these effects occur and warrant careful investigation. It was the purpose of the present study to determine the relative impact of insecticide intake on four phases of pheasant reproduction-egg production, fertility, hatchability, and survival of young. Three chlorinated hydrocarbon insecticides commonly used in California-DDT, toxaphene, and dieldrin--were selected for study. Ringnecked Pheasants (Phasianus colchicus) raised on the State Game Farm at 3⁄4ountville, California, were used as experimental animals.