Meeting Abstract

32.3  Friday, Jan. 4  Allometry of maximal muscular power output in corvids JACKSON, B.E.; Univ. of Montana, Missoula brandon.jackson@mso.umt.edu

Body size has observable influences on virtually all aspects of animal biology, yet we lack detailed understanding of the physical mechanisms underlying many of these patterns. In an effort to examine the allometry of locomotor performance and behavior, I quantified interspecific avian burst take-off and vertical flight performance in passerines � the most speciose clade of birds. To test the hypothesis that muscle mass-specific work is independent of body mass (m), hence power output is dependent on wing-beat frequency (WBF), I measured pectoralis muscle stress, strain, and neuro-control in vivo during vertical flights using surgically implanted strain gauges, sonomicrometry crystals, and EMG electrodes in the largest-bodied clade of passerines, the corvids. The study includes four species spanning an order of magnitude of mass: common raven (Corvus corax), American crow (C. brachyrhynchos), black-billed magpie (Pica hudsonia), and gray jay (Perisoreus canadensis). Herein, I report data from crows and magpies. I quantified flight performance, 3-D wing-beat kinematics, and estimated aerodynamic power by analyzing video from four high-speed cameras. The intact strain gauges were calibrated by simulating the in vivo forces and WBF with a calibrated computer-controlled servo motor attached via steel cable to the pectoralis scar on the delto-pectoral crest of the extracted humerus. Peak muscle strains were high (0.5-0.6) compared to data from wind-tunnel studies, suggesting that all birds performed at or near maximum. The negative allometry of flight performance (proportional to m^-0.3) correlated with variation in WBF (m^-0.3), while muscle strain, stress, and mass-specific muscle work showed no clear trend. These data support the hypothesis that body size imposes constraints on ecology and behaviors related to burst locomotion. Supported by NSF.