Morphological traits of Pacific Flyway Canada Geese as an aid to subspecies identification and management

Journal of Field Ornithology
By:  and 



Subspecies of Canada Geese (Branta canadensis) exhibit wide variation in body size across their range. To monitor harvest levels in the Pacific Flyway, biologists commonly use culmen length and plumage color to differentiate among subspecies on sympatric wintering grounds. Among the four large-bodied Pacific subspecies (B. c. parvipes, B. c. occidentalis, B. c. fulva, and B. c. moffitti), overlap in culmen length and subjectivity of visually assessing color results in misclassification and inaccurate harvest estimates. We examined the morphology of Pacific large-bodied Canada Geese to characterize body size variation among subspecies and provide more discriminatory measures for harvest assessments. We found that culmen length, one of the most commonly used field measures, overlapped widely among subspecies, and it had little support for inclusion in discriminatory models. Morphological measures with greater explanatory power included bill width at nail, bill width at base, head length, and mid wing. If culmen length and plumage color continue to be used to assess winter harvest, we recommend the addition of at least one sex-specific measurement to reduce levels of misclassification among subspecies. If an additional morphological measure is included, further evaluation on the wintering grounds should be conducted as this measure's effectiveness may vary depending upon observer bias, temporal and spatial variation in subspecies abundance, and the proportion of birds accurately sexed by cloacal examination.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Morphological traits of Pacific Flyway Canada Geese as an aid to subspecies identification and management
Series title Journal of Field Ornithology
DOI 10.1648/0273-8570-74.4.357
Volume 74
Issue 4
Year Published 2003
Language English
Publisher Wiley
Contributing office(s) Alaska Science Center, Alaska Science Center Biology WTEB
Description 13 p.
First page 357
Last page 369
Country Canada, United States
Other Geospatial Pacific Flyway
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