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Inability to predict geographic origin of Yellow-headed Blackbirds, Xanthocephalus xanthocephalus, during migration

Canadian Field-Naturalist

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Abstract

Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) collected at different breeding locations in Alberta, Saskatchewan, Manitoba, and North Dakota exhibit clearly discernable morphometric differences with larger bodied birds found at more northern and western locations. We reduced eight skeletal measurements and body length from adult female and male Yellow-headed Blackbirds to their first two principal components. Principal component scores progressively increased at more northwestern locations. Principal component scores were also derived from measurements of birds collected in central North Dakota throughout summer and fall. We hypothesized an increase in principal component scores of Yellow-headed Blackbirds from summer through fall within central North Dakota as larger bodied migrants arrived and displaced local breeding birds. However, we were unable to detect an increase in principal component scores from mid-June though mid-September over two years of study. Discriminant models that were developed to distinguish birds breeding in Canada from those breeding in the USA were poor predictors of the migratory status of Yellow-headed Blackbirds. Thus, we were unable to exploit the morphometric differences inherent among Yellow-headed Blackbirds breeding at different geographic locations to quantify the timing or the magnitude of their migration through central North Dakota.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Inability to predict geographic origin of Yellow-headed Blackbirds, Xanthocephalus xanthocephalus, during migration
Series title:
Canadian Field-Naturalist
Volume
115
Issue:
4
Year Published:
2001
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
549-554
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Canadian Field-Naturalist
First page:
549
Last page:
554