THE FORAGING BEHAVIOR OF MONGOLIAN GERBILS - A BEHAVIORAL NEED OR A NEED TO KNOW

In the present paper Mongolian gerbils (Meriones unguiculatus) were sh own to prefer to forage from an unprofitable food source when it conta ined hidden food, but not when the food was clearly visible. Four expe riments were performed, in each experiment the animal could forage fro m either a food source with easily accessible food or from a food sour ce which required more work. In the first experiment the animal could choose between seeds with husks and those without, and in the second e xperiment between seeds glued to a stick and seeds in a bowl. In both these experiments the animals could see the food of both food sources. The animals chose to forage from the most profitable food source, i.e . the seeds without husks and the seeds in a bowl respectively. In the third experiment the animals could choose between earing seeds hidden under lids or seeds in a bowl, and finally in the fourth experiment t hey could forage for seeds on a camouflaging surface or on a surface w here the seeds were clearly visible. In these last two experiments it was impossible to see the food in the unprofitable food sources withou t working for it. In these situations the animals choose to forage fro m the unprofitable food source, i.e. from underneath the lids and on t he camouflaging surface. These results are in accordance with explorat ion being the driving force behind contrafreeloading (learned industri oussness). The results cannot be explained by classical optimal foragi ng theory.