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Dynamics of the double-crested cormorant population on Lake Ontario

Wildlife Society Bulletin

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Abstract

After nearly 30 years of recolonization and expansion across North America, the double-crested cormorant (Phalacrocorax auritus) occupies the role of a perceived and, in some situations, realized threat to fish stocks and other resources. However, population data necessary to plan, defend, and implement management of this species are few. Our purpose was to gain insight into the relative contribution of various population parameters to the overall rate of population growth and identify data needs critical to improving our understanding of the dynamics of double-crested cormorant populations. We demonstrated the construction of a biologically reasonable representation of cormorant population growth on Lake Ontario (1979-2000) by referencing literature values for fertility, age at first breeding, and survival. These parameters were incorporated into a deterministic stage-classified matrix model. By calculating the elasticity of matrix elements (i.e., statgspecific fertility and survival), we found that cormorant population growth on Lake Ontario was most sensitive to survival of birds about to turn age 3 and older. Finally, we demonstrated how this information could be used to evaluate management scenarios and direct future research by simulating potential environmental effects on fertility and survival, as well as a 5-year egg-oiling program. We also demonstrated that survival of older birds exerts more effective population control than changes in fertility.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Dynamics of the double-crested cormorant population on Lake Ontario
Series title:
Wildlife Society Bulletin
Volume
30
Issue:
2
Year Published:
2002
Language:
English
Publisher:
U.S. Fish and Wildlife Service
Contributing office(s):
Great Lakes Science Center
Description:
p. 345-353
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Wildlife Society Bulletin
First page:
345
Last page:
353