Wildlife Damage Management, Internet Center for


Date of this Version



Proceedings of the 15th Wildlife Damage Management Conference. (J. B. Armstrong, G. R. Gallagher, Eds). 2013. Pp. 54.


The Double-crested Cormorant (Phalacrocorax auritus: DCCO) is lethally managed in many states because of damage to farmed and recreational fisheries. Because a majority of birds culled in the U.S. are migratory cormorants, parasite assemblages may differ from resident birds, due to the diversity of feeding habitats and prey community assemblages encountered over their geographic range. We used multivariate techniques to identify if distinct assemblages and/or proportions of parasites could be identified at the genus level, among geographically different colonies of DCCO. Additionally, we assess the efficacy of models to predict the foraging location of a cormorant based on parasite assemblage.

We assessed the intestinal parasites of 218 DCCO culled from 11 sites in Alabama, Minnesota, Mississippi, and Vermont. Intestines were frozen prior to analysis. Following thawing and defatting, contents including the endothelial layer, were collected from the entire length of the intestine. Parasites were identified to the lowest possible taxonomic level based on previously reported parasites of the Phalacrocorax genus in North America.

The majority of parasites (87%) recovered were digenetic trematodes. Four species of trematode were found to change significantly in abundance (prevalence and/or intensity) with latitude and/or longitude. Similar diversity was noted for cestodes, nematodes, and acanthocephalans recovered from the samples.