Meeting Abstract
Slotted primary feathers are thought to minimize lift-induced drag during translational bird flight. However, recent research has revealed that instead of increasing efficiency during translational flight, such feathers may have a more prominent effect during take-off by maximizing force production. These feathers have a characteristic notch which allow them to separate vertically. Here we address the evolutionary patterns associated with the development of these feathers. We developed a technique for scoring emargination, and we mapped this onto a phylogeny of extant birds to improve understanding of the evolution of these traits. We tested the hypothesis that emargination scales positively with increasing body mass and explored functional aspects of these slotted feathers. We examined the degree of feather emargination in 45 species and show that an intermediate amount of notching may be ancestral. However, notable differences exist, such as the lack of feather emargination within birds of the Laridae family and extreme emargination in the pelican—a species whose clade typically exhibits very little notching. We also quantified the aerodynamic forces acting on the feathers and the subsequent three-dimensional feather deformation (i.e. bending and spanwise twist). Feather bending reorients lift force towards the body and over the center of mass, which may increase passive stability. Funded by the following grants: NSF GRFP DGE−0809127 and DGE−1313190.
