Activity measures for African Pygmy mice in response to dim and bright light

Rodents are integral components of ecosystems as they provide several important ecosystem services. Despite their importance as prey, pollinators and seed distributors, African rodents are largely understudied. The effect of anthropogenic changes such as artificial light at night extend past urban areas to peri-urban and rural habitats and can have profound effects on entire ecosystems. We investigated the effect of dim light at night (dLAN) on the locomotor activity rhythms of the African pygmy mouse (Mus minutoides). Pygmy mice showed a dramatic, intensity dependent reduction in their locomotor activity when subjected to dLAN, which was accompanied by a delay in the activity onset. We also considered masking responses with a dark pulse during the day and a light pulse at night. All animals became inactive in response to a light pulse during the night, whereas approximately half of the animals showed activity during a dark pulse in the day. Our results suggest that the African pygmy mouse is highly sensitive to light and that their activity is strongly masked by light. In their natural environment, vegetation could shield pygmy mice against high light levels, however other anthropogenic disturbances can affect the behaviour of these animals and could affect their survival.

啮齿动物是生态系统不可或缺的组成部分，能够提供多项关键的生态系统服务功能。尽管啮齿动物作为猎物、传粉者以及种子传播者发挥着重要作用，但非洲啮齿动物的相关研究仍十分匮乏。夜间人工光照等人为环境变化的影响范围已超出城市区域，波及城郊与乡村生境，可对整个生态系统产生深远影响。本研究探讨了夜间弱光（dim light at night, dLAN）对非洲侏儒鼠（*Mus minutoides*）运动活动节律的影响。实验结果显示，非洲侏儒鼠在暴露于夜间弱光环境时，其运动活动会出现显著的强度依赖性降低，同时活动起始时间也会出现延迟。本研究同时考察了日间暗脉冲与夜间光脉冲诱导的遮蔽反应。所有受试个体在夜间受到光脉冲刺激时均会停止活动；而约半数个体在日间遭遇暗脉冲刺激时仍会表现出活动行为。本研究结果表明，非洲侏儒鼠对光照高度敏感，其活动行为极易受到光照的遮蔽调控。在自然生境中，植被可帮助侏儒鼠规避高强度光照，但其他人为活动造成的环境干扰仍可能影响该物种的行为模式，进而威胁其生存。