SOME PROBLEMS WITH CURRENT PATCH-CHOICE THEORY - A STUDY ON THE MONGOLIAN GERBIL

Gerbils (Meriones unguiculatus) were allowed to forage during four periods in an environment that contained three bowls; one with sand, the second with 30 sunflower seeds mixed with sand, and the third with just seeds (during period 1) or 250 seeds mixed with sand (during periods 2, 3 and 4). During periods 1 and 2 the animals ate approximately 24 seeds from the 30 bowl. The behavior of working for food while "free food" is present was not influenced by whether or not that food really was "free" or if it was just a question of the amount of work required. During all three stable treatments (1, 2, and 4) the animals began by eating for about 15 min from the 30 bowl and only later changed over to the richest bowl. The big difference in behavior occurred in treatment 3 when the location of the bowls was changed. The animals took significantly less seeds from the 30 bowl (11 seeds), and no pattern like that from 1, 2, and 4 could be found. It is probable that the change in behavior between period 2 and 3 was elicited by the change in certainty of food resources. As the world became more uncertain the animals reduced the explorative part of their behavior and incrased the exploitative part, i.e. they came closer to being short term maximizers. Treatment 4 was equal to treatment 2 and done to control for any learning effects. No such effects were found.