Meeting Abstract

P3.51  Jan. 6  Hold �Em or Fold �Em? Hindlimb Flight Posture in Birds SHEPARD, L.S.*; MEYERS, R.A.; Weber State University, Ogden, UT; Weber State University, Ogden, UT rmeyers@weber.edu

While flying, birds hold their legs in one of two different ways: either in an extended position with the legs trailing behind the body or in a flexed position with the legs tucked under the body. To address why a particular posture is used we first studied which posture is adopted by various flying species. We performed an extensive search of available literature and image libraries, and also photographed a variety of captive species in sustained flight for analysis of limb posture. Groups such as shorebirds, ducks and geese, raptors, owls, parrots, pigeons, cranes, and storks use the extended posture. In contrast, woodpeckers, and perching (song) birds use the flexed posture. The data suggest that limb posture is taxonomically distinct and that variation within taxonomic groups may not occur. We offer three hypotheses to explain variation in limb posture. First, hindlimb posture may represent a structural constraint. Thus, flight posture may be limited by the ability to �package� the hindlimb in an extended or flexed position, or by joint mobility. Second, limb posture may be a behavioral characteristic. For example, birds bring their legs forward prior to landing; perching birds may have evolved the flexed posture because of the ease of landing from this position. Birds using the extended posture may do so because they frequently use their legs and feet to assist in the mechanics of flight. Last, posture may be a historical constraint. Limb posture may represent an ancestral trait of a group and may not necessarily be adaptive. In the course of our investigation on in-flight hindlimb posture, we found that there is very little documentation on the subject, and that the hindlimb posture of birds is likely more important than the amount of prior study would indicate. Supported by WSU.