Formation Flight in the Canada Goose (Branta. C. canadensis)
The function of formation flight in Canada Geese and other large waterfowl is unknown, although two hypotheses have be en proposed. One hypothesis suggests that formation types are a function of visual and spatial needs; the other suggests that these birds are able to reduce induced drag by formatio...
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DigitalCommons@URI
1972
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| Online Access: | https://digitalcommons.uri.edu/theses/739 https://doi.org/10.23860/thesis-lofland-gould-lisa-1972 https://digitalcommons.uri.edu/context/theses/article/1738/viewcontent/QL698.7_.G68.pdf |
| Summary: | The function of formation flight in Canada Geese and other large waterfowl is unknown, although two hypotheses have be en proposed. One hypothesis suggests that formation types are a function of visual and spatial needs; the other suggests that these birds are able to reduce induced drag by formation flight. Published data propose that if formation flight can reduce drag, energy could be saved on long migrations. In this study, autumnal migrating flocks of Canada Geese (Branta c . canadensis) were filmed at a refuge in upstate New York during early October, 1971. The Super-8mm films were analyzed to determine the types of formations utilized, the number of birds per flock, the relationship between wind conditions and flight direction, the angles of Vee and Jay formations, the distance between adjacent birds along the legs of Vee formations, and wing-beat frequencies and phase relationships among the birds in a formation. This study describes a technique to measure the angles of Vee formations, by the use of three-dimensional descriptive geometry, and is the first study in which formation angles have been measured empirically. The results show formation angles much more acute than previously hypothesized, similar wing-beat frequencies among all birds, variable spacing between adjacent birds, and an apparent preference of the majority of the flocks for flight with crosswinds, and at low wind speeds . Due to the variable, and generally large, spacing between adjacent birds along the legs of the formations analyzed, it seems doubtful that these formations could be using the Vee for an aerodynamic advantage. Although the flocks filmed in this study may be more representative of daily movements than of migratory flights, it is possible that the primary function of formation flight may be to maintain flock unity, thus aiding in navigation. Further work is proposed which might resolve the question of a possible aerodynamic advantage to formation flight. |
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