The Vietnamese pygmy dormouse is a small, arboreal, nocturnal, blind rodent that uses incipient echolocation to navigate in tree canopies. In order to assess its arboreal faculties in relation to echolocative capacity, the present study investigated the locomotor and postural behavior of the species in a simulated arboreal environment within an enclosure. The study subjects were intensively video and audio recorded and the two sets of data were synchronized for subsequent analyses. This is the first study on the positional behavior and substrate use of the Vietnamese pygmy dormice. Our results showed that the species spent most of its time on arboreal substrates, mostly traveling and scanning. Locomotion was dominated by vertical climb and leap, occurring mostly on small vertical and on medium and large strongly inclined substrates, respectively. Locomotion and substrate type were strongly related to emission of echolocative pulses. These findings most likely suggest that echolocation compensates for poor vision to effectively negotiate highly challenging arboreal constraints, and are in favor of the arboreal origins of pygmy dormice. Moreover, such a scenario could also support the echolocation-first hypothesis for the emergence of echolocation in bats prior to active flight.

中文翻译：

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越南侏儒睡鼠 Typhlomys chapensis (Platacanthomyidae, Rodentia) 的运动和姿势：盲目攀爬和跳跃

越南侏儒睡鼠是一种小型、树栖、夜间活动的盲啮齿动物，使用初期回声定位在树冠中导航。为了评估其与回声定位能力相关的树栖能力，本研究调查了该物种在围栏内模拟树栖环境中的运动和姿势行为。对研究对象进行了密集的视频和音频记录，并将两组数据同步以进行后续分析。这是对越南侏儒睡鼠的位置行为和基质使用的首次研究。我们的结果表明，该物种大部分时间都在树栖基质上度过，主要是旅行和扫描。运动以垂直爬升和跳跃为主，分别发生在小型垂直和中型和大型强烈倾斜的基底上。运动和底物类型与回声定位脉冲的发射密切相关。这些发现很可能表明回声定位可以弥补视力不佳的问题，以有效应对极具挑战性的树栖约束，并且有利于侏儒睡鼠的树栖起源。此外，这种情况也可以支持回声定位优先假设，即蝙蝠在主动飞行之前出现回声定位。