Dieldrin Mortality of Lesser Snow Geese in Missouri

Abstract

In March and April 1974, 157 lesser snow geese (Chen caerulescens) died from dieldrin poisoning during northward migration through western Missouri. Evidence strongly suggested that the mortality in Missouri resulted from delayed effects upon geese exposed to aldrin-treated rice seed on wintering areas in southeast Texas. J. WILDL. MANAGE. 41(1):100-103 From late March to mid-April 1974, widespread mortality of lesser snow geese occurred in western Missouri. Dead birds were found shortly after the arrival of spring migrants, and mortality continued during the peak of northward migration of snow geese through the state. Dead and dying geese were first observed the last week of March at the Schell-Osage Wildlife Area in west-central Missouri. From 1 through 12 April, mortality was observed near Neosho, Newton County, in southwestern Missouri; Schell-Osage Wildlife Area, Vernon and St. Clair counties; Trimble Wildlife Area, Clinton County; and Squaw Creek National Wildlife Refuge, Holt County, in northwestern Missouri. Delayed effects on birds from stored aldrin-dieldrin residues may occur during the stress of migration at considerable distances from areas where the birds were exposed. This paper provides evidence that snow geese died during migration through western Missouri from aldrin-dieldrin poisoning, and that the most probable source of exposure was on wintering areas of southeast Texas. We express our appreciation to R. Vaught, K. Slagle, R. Baskett, and R. Dobbins of the Missouri Department of Conservation for assistance in determining snow goose losses and collecting specimens for examinations. We thank E. L. McCune, University of Missouri, for necropsies and R. Schoettger and D. Stallings, U.S. Fish and Wildlife Service, for chemical analyses of brain tissue samples for pesticides. We also extend appreciation to C. Stutzenbaker, Texas Parks and Wildlife Department, and G. Nugent, U.S. Fish and Wildlife Service for providing snow goose banding data; J. Szymanski and H. Lobpries ,Garwood, Colorado County, Texas, for collecting goose bands from guides and hunters; and personnel of the U.S. Fish and Wildlife Service, Office of Migratory Bird Management, for providing band recovery records for snow