The single striped mouse (Lemniscomys rosalia)Credit: MK Oosthuizen
In bustling urban areas, artificial light at night is not just a matter of aesthetics, it's a serious concern for wildlife. A recent study considered the impact of artificial light on small rodents.
The study focused on the single-striped grass mouse, Lemniscomys rosalia, an indigenous species found in peri-urban areas close to Johannesburg, Africa's largest metropolitan area. By comparing the activity levels of these mice in both laboratory and natural settings, the researchers aimed to uncover the nuances of how artificial light affects their behaviour.
"Most circadian studies on rodents are done in the laboratory," says Maria Oosthuizen from the University of Pretoria, who worked on the study. “By testing animals in both environments, we can assess their activity levels, and what aspects we can extrapolate laboratory results to field conditions."
Surprisingly, the study revealed that the single-striped grass mouse, typically active at dusk or dawn in nature, became much less active when exposed to artificial light at night (ALAN). This was contrary to the researchers' expectation that artificial light would make the mice more active, to take advantage of the extra light available at night.
"The single-striped mouse did not extend its active time and, in fact, showed a reduction in its overall activity, something that we see in strictly nocturnal species," says Oosthuizen. “ALAN has negative impacts on both nocturnal and diurnal animals. If the impacts are severe enough, it could cause local extinction of certain species.”
