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Low prevalence of Trichomonas gallinae in urban and migratory Cooper's Hawks in northcentral North America.

Article Excerpt
Trichomoniasis is an upper digestive tract disease in birds resulting from ingestion of the protozoan Trichomonas gallinae. T. gallinae occurred in 85% of nestlings examined and ~40% of young in an urban breeding population of Cooper's Hawks (Accipiter cooperii) in Tucson, Arizona died from trichomoniasis (Boal et al. 1998). Urban Cooper's Hawks in Wisconsin and British Columbia exhibited a markedly lower prevalence (5.6% infection) in nestlings with no deaths attributable to trichomoniasis (Rosenfield et al. 2002). There is little information on the prevalence of T. gallinae in populations of this or other raptor species in either urban or rural environs (Rosenfield et al. 2002, Squires and Kennedy 2006). To our knowledge only one study has investigated the prevalence of T. gallinae in adult breeding Cooper's Hawks (Boal et al. 1998), and there are no reports of the prevalence of T. gallinae in migrant individuals.

We examined nestlings and adults at previously unsampled sites in metropolitan Milwaukee in southeast Wisconsin, and in Grand Forks in eastern North Dakota and its abutting municipality of East Grand Forks in western Minnesota. We also sampled for T. gallinae in hatching-year and adult Cooper's Hawks migrating through Hawk Ridge Bird Observatory in Duluth, Minnesota.

METHODS

Study Area.--The study area included the city of Grand Forks in eastern North Dakota, and the adjoining city of East Grand Forks, Minnesota (47[degrees] N, 97[degrees] W), treated as one site (Grand Forks) covering 62 [km.sup.2]. This urban environment included deciduous trees, especially green ash (Fraxinus pensylvanica), American elm (Ulmus americana), and boxelder (Acer negundo) in boulevard, backyard, and cemetery settings surrounded by intensive agriculture and grasslands with few trees. The southeastern Wisconsin study area covered 1,000 [km.sup.2] in metropolitan Milwaukee (43[degrees] N, 88[degrees] W), including the city of Milwaukee (251 [km.sup.2]). The Milwaukee study area had the same deciduous trees (plus oaks [Quercus spp.]) as the Grand Forks site, but landscape composition included high...

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