The Relationship between Wing Shape and Differential Migration in the Dark-Eyed Junco

• Published in: The Auk 1990-07, Vol.107 (3), p.490-499
• Main Authors: Mulvihill, Robert S., Chandler, C. Ray
• Format: Article
• Language: English
• Subjects: Aerial locomotion; Age; Animal and plant ecology; Animal migration behavior; Animal wings; Animal, plant and microbial ecology; Animals; Autoecology; Aves; Biological and medical sciences; Bird banding; Birds; Evolution; Fundamental and applied biological sciences. Psychology; Gender discrimination; Immatures; Junco hyemalis; Vertebrata; Warblers
• ISSN: 0004-8038; 1938-4254

We quantified wing shape in migrant and wintering Dark-eyed Juncos (Junco hyemalis) from southwestern Pennsylvania to assess the relationship between wing shape and differential migration (with respect to distance) among age/sex classes. There were significant differences in wing length and primary distances (distances from the wing tip to the tip of each of the nine primaries) among age/sex classes. Adult juncos had longer wings, larger proximal and distal primary distances, and a wing tip shifted proximally relative to immatures. Males had longer wings and larger proximal primary distances than females, but the sexes did not differ in distal primary distances or wing-tip placement. Wing-shape differences between males and females persisted even after accounting for differences in body mass between the sexes. With few exceptions, wing shape was not correlated with body mass within age/sex classes. The traits usually associated with a pointed wing (the wing shape generally considered adaptive for longer migrations) were really two independent dimensions of wing-shape variation in juncos that did not covary among age/sex classes. Overall, our results are inconsistent with the hypothesis that wing "pointedness" covaries positively with distance migrated in juncos.