Researchers: Nicholas Duenas
Affiliation(s): California State University, Northridge
Summary: Light pollution, or artificial light at night (ALAN), can increase an animal’s sense of perceived risk while out foraging. This can cause them to leave more food at foraging sites or visit them less often in favor of safety from predation. For populations of small nocturnal rodents, this can cause negative trophic effects on plant communities in an ecosystem. To measure an increase in perceived risk from ALAN, I measured the giving up densities (GUDs) of small rodents foraging at six illuminated and six non-illuminated sand filled trays. I used low levels of light (0.5 lx) to illuminate the trays since nocturnal rodents have excellent night vision. Camera traps were used to measure how often the rodents foraged at illuminated and non-illuminated trays. Rodent GUDs were measured at the edges of oak woodland and shrubland habitats. Lunar illumination and cloud coverage at night were also recorded to determine how the increase and decrease of natural nocturnal light interacted with ALAN. ALAN was a risk factor in both environments. Rodent GUDs increased as moon illumination increased. Rodents also visited illuminated trays less often than non-illuminated trays. Understanding the impacts of ALAN on rodent foraging behavior and predation perception can help biologists protect these animals. This information can also help conservationists mitigate the negative effects of ALAN on wildlife living close to human developments.