Meeting Abstract
The avian tail is used to facilitate locomotion and perform specific behaviors. For example, woodpeckers use their depressed tail as a prop to increase stability while climbing and drilling on trees. We used immunohistochemistry to quantify fast and slow fiber types in eight tail muscles from five Northern Flickers (Colaptes auratus), three Rock Pigeons (Columba livia), three Yellow-headed Blackbirds (X. xanthocephalus), two Red-winged Blackbirds (Agelaius phoeniceus), four Black-billed Magpies (Pica hudsonia), and one Western Scrub-Jay (Aphelocoma californica) to ascertain a relationship between fiber composition and behavior. Muscle fiber types differ in contraction speed: fast fibers are best suited for dynamic (i.e., locomotor) action while slow fibers are associated with postural functions. M. levator caudae (tail elevation) contained fast and slow muscle fibers in all species. M. depressor caudae (tail depression) was entirely fast in adult blackbirds, jays, and magpies; in flickers it contained a population of slow fibers. We believe that the slow fiber populations found in Mm. depressor caudae and levator caudae are correlated with distinct behaviors in these species. Birds generally maintain an elevated tail position against gravity implying a postural function for the slow fibers in levator caudae in all species. Woodpeckers rely on their tail for support during climbing and maintain it in a depressed position. Slow fibers in this muscle would facilitate isometric contractions of sustained tail depression associated with this behavior in flickers. Study of additional species of woodpeckers to validate the structure/function relationship is warranted.
