Sarcomere length changes in the wing muscles during the wing beat cycle of two bird species

Sarcomere lengths were measured (using a method based on diffraction) in carcasses of Melopsitlacus undulatus and Taeniopygia guttata , with the wings set by rigor mortis in various positions simulating flight. The results indicate that in flight the major wing muscles work between minimum sarcomere lengths of 1.7–1.9 μm, and maximum sarcomere lengths of 2.1–2.3 μm. This range probably corresponds to the upper part of the ascending limb, and the plateau, of the length‐tension curve.