Kinematics of swimming of penguins at the Detroit Zoo

Abstract

Kinematic parameters were examined in a study of the swimming abilities of seven species of penguins housed at the Detroit Zoo. Penguins produce thrust over both halves of the wing stroke cycle, as observed in fishes using the caudal or pectoral fins for locomotion, but not in other birds in level forward flight. Unpowered gliding phases between wing strokes were observed in all species at swimming speeds less than 1.25 m/sec, while Emperor, King and Adelie penguins interpose gliding phases over a broad range of speeds. Videotape records reveal that length‐specific speed is correlated with increases in wingbeat frequency and, for most of the species examined, stride length. These findings are in contrast to those reported for other, flying birds, which maintain a relatively constant wingbeat frequency but vary stride length with forward speed, and for most fishes, which vary speed with tailbeat frequency but maintain a constant stride length. The results are somewhat comparable to those reported for Cymatogaster, a fish which uses the pectoral fins for locomotion. Drag coefficients of three gliding Emperor penguins were 2.1, 3.0 and 3.0 × 10‐−3 at Reynolds numbers of 1.25, 1.62 and 1.76 × 106, respectively.