Aerial applications of DDT in oil at the rate of 2 pounds per acre applied over a four-year interval on bottomland forest resulted in a 26 percent decrease in the breeding bird population by the fifth spring. The American redstart, parula warbler, and red-eyed vireo suffered decreases of 44 percent, 40. percent, and 28 percent, respectively, over the four-year period. Only the redstart decreased significantly immediately following application of the spray; a few days after the first, second, and fifth annual sprayings an average of 23 percent of redstart territories were deserted. No significant decrease was observed for other species, either immediately following spraying, or over the four-year period.
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Effects of five-year DDT application on breeding bird population