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Eggshell quality and organochlorine residues in eggs of merlins, Falco columbarius, in southeastern Montana

Formally Refereed

Abstract

Eggshell weight and thickness indices of Richardson’s Merlin (Falco columbarius richardsonii) eggs collected in southeastern Montana were significantly (p < 0.01) lower than pre-1946 samples. Montana eggshells showed reductions of 13% in shell weight and 20% in shell thickness indices when compared to eggshells collected before 1946. The decreased eggshell weights and thickness indices and the occurrence of 7 organochlorine compounds in Merlin eggs recently collected in southeastern Montana indicates that this raptor population merits periodic monitoring.

Keywords

0rganochlorines, Merlin, Falco columbarius, pesticides, Montana

Citation

Becker, Dale M.; Sieg, Carolyn Hull. 1987. Eggshell quality and organochlorine residues in eggs of merlins, Falco columbarius, in southeastern Montana. Canadian Field-Naturalist. 101(3): 369-372.
https://www.fs.usda.gov/research/treesearch/22792