Changes in foraging behavior of two species of field mice,Apodemus speciosus Temminck andA. argenteus Temminck (Rodentia: Muridae), in the response to artificial illumination

Abstract

Predation hazard is one of the most important factors that affect foraging behavior. Light intensity is an indirect measure of a predation hazard for nocturnal rodents. In 1988 and 1989, I conducted laboratory experiments to reveal the effects of the predation hazard on foraging behavior of two species of field mice,Apodemus speciosus Temminck andA. argenteus Temminck (Rodentia: Muridae), which co-exist in many areas in Japan. I released a mouse into the experimental arena, where I set one nest box and two food stations (one near and the other far from the nest box), and recorded the foraging behavior for sixA. speciosus and sixA. argenteus mice. I planned to illuminate the experimental arena when the mouse left the nest box to mimic a predation hazard during excursion. The light treatment decreased the time the mouse spend outside the nest box, the duration of an excursion, the number of visits to the food station far from the nest box, and the number of peanuts handled at the food station far away. Mice handled food more intensely at the food station near to the nest box and tended to carry more foods back to the nest box and eat them there during the light treatment period than the control period. These behavioral changes, which seemed to be adaptive to avoid the predation hazard in the field, were more apparent in smaller mice,A. argenteus, than larger mice,A. speciosus.