Hopping and climbing gait of Japanese Pygmy Woodpeckers (Picoides kizuki)

Single cycles of hopping and climbing were investigated in Japanese Pygmy Woodpeckers Picoides kizuki using motion analyses on video. Body movements on substrate angled from 0–90° were compared for every 10°. The body was inclined forward during stance phase for both small and large substrate angles, and the inclination amplitude increased when the substrate angle increased. The tail was bent ventrally almost simultaneously to this body inclination, and its amplitude was apparently high at large substrate angles. Most of the gait parameters changed when the stride length increased. The minimum body–tail angle and most of the parameters representing body movements during stance phase changed when the substrate angle increased, probably because gravity pulled the birds further backward when they were moving on a steeper slope. These parameters showed a clear difference between the data on substrate steeper than 40° and lower than 30°. The abrupt changes in these parameters most likely mean that the motor pattern changed from hopping to climbing between these angles.