Relative nesting success of yellow headed blackbirds xanthocephalus xanthocephalus and red winged blackbirds agelaius phoeniceus
Transactions of the Wisconsin Academy of Sciences Arts and Letters 73: 133-134
At Collins Marsh, Manitowoc Co., Wisconsin [USA], Red-winged Blackbirds fledge significantly fewer young per nest and have a significantly higher rate of nest failure than Yellow-headed Blackbirds. As a result of interspecific territoriality Red-wings are prevented from breeding in areas they would otherwise use. Thus, competition for nesting habitat results in lowered reproductive rates among Red-wings. A major factor causing the lower reproductive rates is increased egg predation.