Previous studies had shown that heavy or repeated applications of DDT resulted in decreases.in bird populations, but long-range effects of this and other chlorinated hydrocarbon insecticides had not been fully evaluated. Experiments were conducted to determine toxiCitY to quail and pheasants of aldrin, dieldrin, endrin, and strobane, and to determine effects of these compounds upon survival, growth, and reproduction....Feeding of diets containing 0.02% DDT to breeding quail resulted in significant decreases in hatchability of eggs and in viability of chiCks. Similar results were obtained by feeding 0.001% dieldrin, but effects upon reproduct.ion of short-term feeding of aldrin and endrin could not be determined....Aldrin, dieldrin, and endrin were lethal to both male and female quail when fed at levels of 0.0005% in the diets. Female pheasants appeared more resistant than males to the effects of these compounds.