The effect of aggregated nesting on Red-winged Blackbird nest success and brood parasitism by Brown-headed Cowbirds

There is no effect of spatial or temporal nesting aggregations on nest success in Red-winged Blackbirds, according to research focusing on the effects of aggregated nesting on blackbird nest success and brood parasitism by Brown-headed Cowbirds. The findings of this research were in line with the view that marsh-nesting populations of Red-winged Blackbirds are less vulnerable to parasitism than upland-nesting populations as high nest density allows cooperative vigilance and deterrence. However, the findings go against many studies indicating that predation is negatively correlated with nest density.