9523963 Vazquez Birds must use muscles of the shoulder and back to maintain horizontal body posture during flight. Otherwise, the body orients itself vertically relative to the extended horizontal wings. Previous researchers have hypothesized about the muscles responsible for generating horizontal body attitude, but no experimental analyses have yet been conducted. The objective of this study is to experimentally determine the muscles involved in aligning the body of a bird in a horizontal attitude during level forward flight. Through the minute electrode wires each muscle will receive electrical impulses that will induce contraction. This protocol enables the investigator to determine which muscles are responsible for posturing the bird's body horizontally during flight. The proposed research will attempt to add another piece to a puzzle that has engaged man for centuries; how does a bird fly? Though the final answer to this question will no doubt be very complicated and multifaceted, it is possible to make a significant contribution to the elucidation of this phenomenon by understanding the adaptations in the shoulder that allow the body to attain an aerodynamic posture and work in unison. ***