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  Brown-headed Cowbird  
  (Molothrus ater)  

brown-headed cowbirds.jpg

  The Brown-headed Cowbird is another bird species that has expanded its range into Quebec during the last century. Closely associated with domestic cattle, this bird often feeds on the insects associated with grazing cattle. Unfortunately, the Brown-headed Cowbird is notorious as a brood parasite. This means that it never builds a nest but,instead, lays its eggs in the nests of other species of songbirds. A single cowbird can lay up to 40 eggs per year. This bird has successfully parasitized the nests of over 144 bird species! Furthermore, cowbird hatchlings are substantially larger than the host species, making the chance of survival of the host species low. Considering these conditions, it is not surprising that the Brown-headed Cowbird has been highly successful during this century. The Brown-headed Cowbird poses one of the most severe threats to populations of native songbirds. Although it normally inhabits open habitats, pastures, and forest edges, increased forest fragmentation has allowed cowbirds to penetrate forested area, and parasitized nests have been found more than 4 km from Cowbird habitat. In light of these findings, adequate protection of songbird populations from parasitism requires the protection of large tracts of continuous forested land, rather than isolated patches of forest.  
  Distribution of the Brown-headed Cowbird in S. Quebec:  
  distribution map.jpg  


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