Dicofol (Kelthane?)-induced eggshell thinning in captive American kestrels

Environmental Toxicology and Chemistry
By: , and 



Reproductive parameters of American kestrels (Falco sparverius) were measured through two breeding seasons. Exposure to Kelthane? (containing no DDT-related compounds) at dietary concentrations of 0 (contro!), 1, 3, 10 and 30 ug/g (wet weight) began in late November before, and continued through, the second season. Kelthane thinned eggshells and lowered the thickness index at dietary concentrations >3 ?g/g and it reduced shell weight at >10 ?g/g when comparisons were to concurrent controls. Kelthane reduced the thickness index at >3 ug/g and it reduced shell thickness and weight at >10 ug/g when comparisons were to the same birds during the previous season. All changes were dose-related. It was not previously known that as little as 3 ug/g dicofol could cause these effects. Kestrels resembled previously studied eastern screech-owls (Otus asio) in that 10 ug/ g reduced hatchability of eggs. Both these raptors showed eggshell changes without serious effects on production of young. Available data show dicofol only equal to or less effective than DDE as a shell-thinning agent. Also, DDE may have more impact than dicofol on such critical aspects of reproduction as egg hatchability and survivability of hatchlings. Field studies of dicofol residues in food chains and of residue concentrations in eggs vs. nesting success from areas of heavy dicofol use are needed to judge this chemical's ecological impact.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Dicofol (Kelthane?)-induced eggshell thinning in captive American kestrels
Series title Environmental Toxicology and Chemistry
Volume 9
Issue 8
Year Published 1990
Language English
Contributing office(s) Patuxent Wildlife Research Center
Description 1063-1069
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Environmental Toxicology and Chemistry
First page 1063
Last page 1069
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