Meeting Abstract

S5.3-3  Sunday, Jan. 5 14:30  Dynamics of locomotor transitions from arboreal to terrestrial substrates in Verreaux’s sifaka (Propithecus verreauxi) WUNDERLICH, R.E.*; MILLER, C.E.; TONGEN, A.L.; SCHMITT, D.; James Madison University; Duke University; James Madison University; Duke University wunderre@jmu.edu

Sifakas are indrid primates whose primary mode of locomotion is arboreal vertical clinging and leaping. On the ground, they use bipedal galloping gait characterized by asymmetrically sequenced limb contacts, a single re-direction of the center of mass and an aerial phase. Bipedal galloping and leaping in sifakas share kinematic features, yet the energetics and loading regimes of these two forms of locomotion are poorly understood. We used triaxial accelerometry to quantify dynamic body accelerations during a variety of locomotor behaviors. Accelerometers were mounted on free-ranging animals for whom locomotor behavior was recorded over 4 hours. Acceleration (100Hz) was recorded by datalogger, smoothed, and components summed to produce overall dynamic body acceleration (ODBA). Peak ODBA values over 20 Hz were identified as leaps. Leaping could be clearly identified compared to all locomotor behaviors other than bipedalism, which exhibited similar ODBA. A single leap or bipedal gallop consists of take-off and landing ODBA peaks. In both leaping and bipedalism, sifakas regularly use repeated or richochetal movements in which the landing ODBA of one leap is the takeoff ODBA of the next, resulting in one fewer ODBA peaks than would be expected from a series of single leaps. By using the landing acceleration to accelerate for the next take-off, sifakas minimize collisional energy losses by reducing the number of center of mass redirections by 1 each leap. Arboreal leaping and terrestrial bipedal galloping are dynamically similar locomotor patterns that use similar mechanisms for minimizing energetic costs.