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.