Toxicity of dieldrin to bobwhite quail in relation to sex and reproductive status.

In a study of dieldrin toxicity to breeding and nonbreeding bob-white quail (Colinus virginianus), breeding birds of both sexes on long photoperiods were more susceptible to dieldrin poisoning than nonbreeding birds, although some differences were not statistically significant at the .10 level. Shortened photoperiods caused gonadal regression, weight loss, and additional mortalities among dieldrin-treated birds previously in breeding condition. Dieldrin did not influence food consumption, body weight, or egg production until about a week or less before death of individual birds. Dieldrin brain residues were higher among birds that died during the study than among survivors sacrificed at its termination. Among those that died, neither dieldrin treatment level, reproductive status, nor sex seemed related to brain residue levels. Nevertheless, within those factors, levels were slightly higher in the birds that died later in the test.