Aerial maneuvering by plethodontid salamanders spanning an arboreality gradient.

Abstract

Wandering salamanders (Aneides vagrans) inhabit the crowns of the world's tallest trees, taking refuge in epiphytic fern mats within these complex arboreal environments. These salamanders readily jump from the canopy when disturbed and maintain stable postures while falling via fine adjustments of the limbs and tail in lieu of dedicated aerodynamic control surfaces, thus reliably carrying out non-vertical descent. Here, we examined the aerial behavior and performance of A. vagrans and three other species of plethodontid salamander across a habitat gradient of arboreality by recording salamanders falling from short heights and moving within the jet of a vertical wind tunnel. Kinematic performance of aerial behavior in plethodontid salamanders was correlated with a gradient of arboreal habitats; moreover, salamanders from arboreal niches were more effective in slowing and redirecting descent compared with other salamanders. Aneides vagrans and the closely related Aneides lugubris consistently engaged in parachuting and gliding when falling; their trajectories were very steep, but were sufficiently angled to enable contact with either the home trunk or nearby branches during falls or jumps from great heights. Aerial maneuvering in arboreal salamanders is similar to that seen in other vertebrates capable of non-vertical and controlled descent, suggesting that the long limbs and active tail of these arboreal plethodontids (often cited as adaptations for climbing) may also contribute to parachuting and gliding when falling from trees. These aerial behaviors within the redwood canopy warrant further investigations into other canopy residents that lack conspicuous surfaces for aerodynamic control.