Effects of DDT on Bird Population of Scrub Forest

Abstract

An oil spray of DDT was applied at the rate of 5 lbs. per acre to a 90-acre tract of 5-yr.-old scrub and sapling growth at Beltsville, Md. Bird population studies were carried on in a 30-acre plot at the center of the sprayed area, and in a 30-acre check area of the same habitat one-half mile away. Of the 5 commonest spp. in the sprayed area, the Maryland yellow-throat (Geothlypis trichas), prairie warbler (Dendroica discolor), and house wren (Troglodytes aedon) were reduced 80%, and the red-eyed towhee (Pipilo erythrophthalmus) was apparently reduced 35%; while no appreciable change in the numbers of yellow-breasted chats (Icteria virens) was noted. The total decrease for the 5 commonest spp., which represented 77% of the original population, was 65%.