Parasitology, Harold W. Manter Laboratory of


Date of this Version


Document Type



United States Fish and Wildlife Service, Resource Publication 142, September 1981, 156 pages

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United States government work

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This key is the second in a series for identification of the helminths reported in waterfowl (Family Anatidae, Order Anseriformes). The first was a key to nematodes (McDonald 1974).

The trematodes show the greatest variety of forms among the helminth parasites of waterfowl, including over half of all species reported; sometimes this group also includes the greatest part of the worms in a single bird. Over 500 species of trematodes have been reported in waterfowl. Almost all of these have been included in the present set of keys; it was not possible, however, to obtain the descriptions of a few forms (7 of 525).