Influence of moonlight on visits to water sources by mammalian predator and prey: a test of competing hypotheses

Predator–prey interactions are influenced by the ability of the parties to visually perceive each other. Changes in moonlight across the lunar cycle may influence visibility of predator and prey and how they interact with each other and access shared resources (e.g. water sources in the desert). We tested three competing hypotheses explaining the nocturnal activity of mammalian predator and prey at desert water sources (i.e. predation risk allocation hypothesis, visual acuity hypothesis, physiological need for water hypothesis). We used camera traps at water sources in the Great Basin Desert to monitor mammalian predators (bobcat, Lynx rufus; coyote, Canis latrans) and their shared prey (black-tailed jackrabbit, Lepus californicus; mule deer, Odocoileus hemionus; pronghorn, Antilocapra americana). We used generalized linear mixed-effects models and model selection to evaluate the influence of moonlight on the nocturnal activity of predator and prey after accounting for other influential abiotic and biotic factors. Responses to moonlight varied across species, with the activity of black-tailed jackrabbits and pronghorn being lunarphilic, the activity of coyotes being lunarphobic and the activity of bobcats and mule deer not associated with changes in moonlight. Our findings provide partial support for the visual acuity hypothesis and the physiological need for water hypothesis but do not support the predation risk allocation hypothesis in a desert predator–prey community.