Content area
Full text
We studied the effect of ecological light pollution on a rocky desert community, focusing on 2 spiny mouse congeners, nocturnal Acomys cahirinus (common spiny mouse) and diurnal Acomys russatus (golden spiny mouse). We hypothesized that in response to artificial illumination A. cahirinus will decrease its activity and A. russatus will increase its activity, and thus temporal overlap and interspecific competition could increase. Our study took place in 4 field enclosures: the 1st and 3rd months were controls with natural light, and in the 2nd month artificial illumination, simulating low levels of light pollution, was set for the first 3 h of the night. We implanted temperature-sensitive radiotransmitters to monitor mouse activity, and individual identification tags with automonitored foraging patches were used to track foraging behavior. A. cahirinus decreased activity and foraging with artificial lighting, restricting movement particularly in less-sheltered microhabitats, probably because of increased predation risk. Because illumination restricted both activity time and space, intraspecific encounters of A. cahirinus over foraging patches increased during and following the illuminated hours. However, diurnal A. russatus did not expand its activity into the illuminated hours, possibly due to the presence of competing A. cahirinus, or to nonfavorable environmental conditions. Therefore, overt interspecific competition was not affected by experimental light pollution. Light pollution had a negative influence by reducing overall activity and producing a relatively underexploited temporal niche, which may promote invasion of alien species that are less light sensitive; and by increasing intraspecific overlap in foraging A. cahirinus.
Key words: Acomys cahirinus, Acomys russatus, activity patterns, light night niche, light pollution
© 2011 American Society of Mammalogists
DOI: 10.1644/10-MAMM-A-112.1
Artificial illumination allows humans to expand their activity during the night. As people alter natural areas and build new settlements and infrastructures, artificial lighting increases. The phenomenon of artificial lights that alter natural light patterns in ecosystems was termed ecological light pollution by Longcore and Rich (2004). Any artificial light (e.g., streetlights, vehicles, and fishing boats), however low or sporadic, can be a source of such pollution. Conservative estimates suggest that in 2001 at least 18.7% of the terrestrial area of Earth was exposed to ecological light pollution (Cinzano et al. 2001), and it continues to rise with human populations and technological development.
Ecological light pollution is an...