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Ursidae: The Undergraduate Research Journal at the University of Northern Colorado

Faculty Sponsor

Lauryn Benedict

Abstract

This study examined how Rock Wren (Salpinctes obsoletus) wing shape varies with latitude and relates to the presence or absence of migration. Existing research on other species has demonstrated that long, narrow wings are ideal for longer distance travels such as migration trips, while short, rounder wings are best suited for quick take-offs and maneuverability. Currently, there is no data on how wing morphology relates to migration in the Rock Wren populations of North America. Rock Wrens provide a great opportunity for studying this topic because their migratory and sedentary populations are separated; northern Rock Wrens migrate and southern ones do not. For this study, 90 captured and released Rock Wrens were photographed and measured for their hand wing index (HWI), a measure of wing pointedness, using the computer program Adobe Illustrator. These birds came from nine breeding/capture locations in a North-South transect across The United States from Texas to Wyoming. The average Wing Length (WL) was 68.96 millimeters and the average secondary length (SL) was 58.82 millimeters with an average HWI of 14.48. There was variation in HWI between populations. Expected results were to see larger hand wing indices, (longer, narrower wings) as you move north, and smaller hand wing indices (shorter, rounder wings) as you move south. Contrary to the hypothesis, the results showed an increase in hand wing index as you moved south. The more southern, sedentary populations exhibited relatively longer and narrower wings. The cause of this is unknown and continued research is needed to figure out why this trend exists. This study and follow-up work will continue to help us understand how migration manifests physically within this species, and how it relates to global patterns.

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