Effects of contaminants on Double-crested Cormorant reproduction in Green Bay, Wisconsin, USA

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Edited by:
N.J. Adams and R.H. Slotow


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In 1994 and 1995, Double-crested Cormorants Phalacrocorax auritus were monitored from egg-laying through 12 days of age at Cat Island, Green Bay, Wisconsin, USA. Sample eggs at hatching were analysed for organochlorines (including total PCBs, PCB congeners, and DDE), hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity in livers of embryos, and eggshell thickness. The number of eggs per nest that hatched and survived to i 2 days of age was estimated to be 2.2 in 1994 and 2.0 in 1995. Hatching success of eggs was not correlated with PCBs, the toxicity of PCBs based on congeners, or EROD activity. Hatching success was correlated with eggshell thickness and negatively correlated with DDE concentrations. Even though the insecticide DDT was banned in the early 1970s, we suggest that DDE concentrations in cormorant eggs in Green Bay are still having an affect on reproduction in this species.

Additional publication details

Publication type:
Book chapter
Publication Subtype:
Book Chapter
Effects of contaminants on Double-crested Cormorant reproduction in Green Bay, Wisconsin, USA
Year Published:
Bird Life South Africa
Publisher location:
Johannesburg, South Africa
Contributing office(s):
Patuxent Wildlife Research Center
on CD-ROM: lxxxi, 3229
Larger Work Type:
Larger Work Subtype:
Other Government Series
Larger Work Title:
Proceedings 22nd International Ornithological Congress, 16-22 August 1998, Durban.
First page:
J022 (abst