02542nas a2200289   4500008004100000245011500041210006900156300001300225490000800238520164800246653002401894653001701918653002101935653003101956653001501987653001302002653001902015653002402034653002502058653002002083653001702103100001702120700001702137700001902154700002002173856005902193       2010                        eng d00aCommunity-level patterns of host use by the Brown-headed Cowbird (Molothrus ater), a generalist brood parasite0 aCommunitylevel patterns of host use by the Brownheaded Cowbird M  a263 -2730 v1273 a<p>Quantifying community-level host use by generalist brood parasites is important because it provides a measure of the resources that parasites need for reproduction. During the 2002&ndash;2007 breeding seasons, we quantified host use by the Brown-headed Cowbird (Molothrus ater) at Konza Prairie Biological Station in northeast Kansas. Overall, 54.4% of nests (n = 2,621) of 22 passerine host species that typically accept parasitic eggs were parasitized, and parasitized nests contained an average of 1.9 &plusmn; 1.03 (SD) Brown-headed Cowbird eggs, nestlings, or both. Multiple parasitism was common on the study site in all years: 55.7% of parasitized nests (n = 1,425) received &ge;2 Brown-headed Cowbird eggs. The Bell&#39;s Vireo (Vireo bellii; 70.5%) and the Dickcissel (Spiza americana; 69.6%) were parasitized at a significantly greater rate than the Red-winged Blackbird (Agelaius phoeniceus, 21.9%); collectively, these three species represented 85.8% of potential host nests found in all years. The host preference of Brown-headed Cowbirds did not appear to shift among the three species and instead they exhibited a consistent preference for Dickcissel nests over the course of the breeding season and among years. Both the rate and the intensity of parasitism on Dickcissels were significantly lower during the present study than in one conducted several decades earlier at the same site. Our results indicate that cowbirds in northeast Kansas differentially parasitize hosts, that most cowbird eggs are laid in the nests of a small number of host species, and that the Dickcissel appears to be preferred over other hosts.</p>10aAgelaius phoeniceus10aBell's Vireo10abrood parasitism10acommunity-level parasitism10aDickcissel10ahost use10aMolothrus ater10amultiple parasitism10ared-winged blackbird10aSpiza americana10aVireo bellii1 aRivers, J.W.1 aJensen, W.E.1 aKosciuch, K.L.1 aRothstein, S.I.  uhttps://academic.oup.com/auk/article/127/2/263/5148382