Effects of DDT on Birds at the Patuxent Research Refuge

Abstract

An experimental aerial application of DDT at 2 pounds per acre was made on a 117-acre tract (Fig. 1) within the Patuxent Research Refuge on June 5, 1945, in cooperation with the Division of Forest Insects, U. S. Bureau of Entomology and Plant Quarantine. The spraying was arranged for by that Division through Dr. F. C. Craighead. The chief objective of the test was to determine the effects of such an application on wildlife. The DDT was sprayed as an oil solution from an N-3N Navy trainer airplane, using a tank equipped with a gear pump which metered the DDT solution into a hollow pipe provided with spray nozzles. The pipe was attached beneath and extending the length of the lower wing. The solution comprised 1 pound of DDT, 2 pints of xylene, and 5.7 pints of No. 2 fuel oil; and an effort was made to apply 2 gallons to each acre of land. This spray was applied within a few feet of the top of the forest canopy on a relatively quiet evening. Observers in the vicinity of the study area at the time of spraying reported considerable loss of spray by drift of fine oil particles. The sprayed area was within the well-drained bottomland forest type, which was selected as that most likely to yield the most reliable results because of its dense breeding bird population. Three study areas (Fig. 1, Nos. 1, 2, 3), all within this type, were studied intensively during May and June. Area No. 1, of 31 acres, was within the sprayed region, Area No. 2, of 32 acres