Effects of DDE and food stress on reproduction and body condition of ringed turtle doves

The effects of food restrictions and DDE exposure on the reproduction and body condition of ringed turtle doves were investigated, using breeding pairs. The experimental design is described. When food intake was reduced to 90, 80, and 70% of normal, overall productivity in unexposed birds was reduced 50, 85, and 100%, respectively. In DDE-exposed pairs, productivity was reduced 87, 98, and 100%, respectively, at these feeding levels. Food restrictions before pairing had a greater effect than food restrictions at egg laying. Most behavioral changes, induced by DDE exposure and food deprivation, were seen in females. The food restrictions apparently reduced reproductive success by limiting hormones needed to develop and maintain active gonads, adequate courtship and brooding behavior, and functional crop glands. DDE alone did not influence the number of pairs attempting to beed; nonbreeding occurred only with food restriction, and then DDE residues in birds aggravated the effects.