As part of the registration process for agricultural pesticides in the United States, Short-Term Field Tests for Hazard to Birds (small pen studies) are sometimes required for pesticides exhibiting moderate acute toxicity (Environmental Protection Agency 1978). We conducted such a small pen study to determine the chronic hazards of bendiocarb (an insecticide designed to control corn rootworms, trade name TATTOO, Fisons Ltd., Essex, England) to birds. Bendiocarb is a moderately toxic N-methyl N-dimethyl compound typical of the carbamate group of insecticides introduced into the United States in the mid-1950s. The small pen study was conducted with Northern Bobwhites (Colinus virginianus) under normal agricultural conditions. The scope of the study was expanded to include fatty acid analysis of eggs and body tissues of experimental birds, determination of energy content of eggs, quantitative measures of bobwhite mobility and activity, and analysis of brain cholinesterase activity. Major modifications of any of these parameters could pose adverse ecological problems for wild avian populations. This report presents the results of this small pen study and is contribution No. 85-347-J, Division of Biology, Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS 66502