First record of Bronzed Cowbird parasitism on the Great-tailed Grackle.(Short Communications)

Publication: Wilson Bulletin

Publication Date: 01-JUN-05

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The five species of brood parasitic cowbirds (Molothrus spp.) differ greatly in the numbers of hosts they use. Brown-headed (M. ater) and Shiny (M. bonariensis) cowbirds are known to have parasitized more than 200 hosts, while the Giant (M. oryzivorus) and Screaming (M. rufoaxillaris) cowbirds parasitize 10 host species or less (Ortega 1998). The Bronzed Cowbird (M. aeneus) uses an intermediate number of hosts, with a total of 95 known host species (Lowther 1995, Sealy el al. 1997, Lowther 2004). Lanyon (1992) and Rothstein et al. (2002) have discussed alternative evolutionary scenarios for the evolution of host use and the relationship between the number of hosts used by each cowbird species and its branching order in the phylogeny of cowbirds. Additional data on host use are needed to resolve these issues, especially for the Neotropical cowbird species, in part because the number of recorded hosts is influenced by various biases, such as research effort, range, and even body size of a particular cowbird species (Rothstein et al. 2002).

The Bronzed Cowbird is one of the least studied cowbird species (but see Carter 1986, Peer and Sealy 1999b, Chace 2004) and new data on its host use are especially valuable and could lead to tests of the hypothesis...

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