Figure 5.

Transmission ratio, the ratio of wing flapping amplitude to muscle strain, was found to vary proportional to mass^−0.20 (r² = 0.77, p = 9.38e − 8) among a variety of insect and bird species. The transmission ratio of the hummingbird species examined here, Archilochus colubris, was larger than that of any other bird but is not particularly unusual in the context of this broad scaling relationship. Although these data include two closely related groups, a phylogenetically based regression analysis produced a nearly identical scaling relationship [15] (filled square, A. colubris; circles, Corvidae; diamonds, Phasianidae; open squares, other birds; triangles, insects).