![](/wp-content/uploads/2021/03/abstractheadergraphic2010.gif)
Meeting Abstract
70.2 Wednesday, Jan. 6 Scaling of escape flight performance, power output, and muscle function in perching birds JACKSON, B.E.; The University of Montana, Missoula brandon.jackson@mso.umt.edu
Patterns of scaling in animal locomotion offer insight to physical constraints imposed on evolution. Flight, being metabolically costly yet evolutionarily successful, is a particularly useful locomotor behavior through which to examine effects of scaling on locomotor performance, behavior, and ecology. Order Passeriformes (perching birds) includes ~50% of extant avian species, and a diverse array of ecologies, making them a critical component to our understanding of scaling in birds. I used a phylogenetically controlled 3-D kinematic analysis of 32 species of passerines (5 – 900 g) performing maximal escape takeoff and vertical flight. Body mass (Mb) specific climb power output scaled as Mb-0.17, controlling for typical foraging location (ground vs. elevated). Total mass specific power output estimated from aerodynamic models scaled as Mb-0.10, and was limited by a ceiling that scaled approximately as Mb-0.2. Ground foraging species performed significantly better than elevated foragers, and resident species performed marginally better than long-distance migrants. Ground foragers also had relatively shorter wings, higher wingbeat frequencies, and greater hind-limb contribution to takeoff. In a complementary study I measured in vivo muscle function using sono-strain surgical implants in a single passerine clade, Corvidae (Gray Jay, Black-billed Magpie, American Crow, and Common Raven). Muscle mass (Mm) specific mechanical power output scaled as Mm-0.2. In both muscle output and whole-body performance, wingbeat frequency appears to impose an ultimate limit. However, the positive allometry of muscle strain (Mb0.11) and wing size (length: Mb0.41) are potential compensatory mechanisms reducing the effects of body size on whole-body performance via wingbeat frequency. Funded by NSF IBN-0417176.