AN EXPERIMENTAL INVESTIGATION OF A NEW IDEAL FREE DISTRIBUTION MODEL

We investigate a new continuous input ideal free distribution model wh ich removes the assumption that resources are consumed as soon as they enter a patch. The model makes predictions about the standing crop of resources and allows consideration of the effects of simultaneous exp loitation and interference competition. Using a group of cichlid fish competing for food items, we show that consistent with the model, stan ding crops can vary in continuous input situations. As predicted, high er standing crops are associated with increased intake rates. Furtherm ore, with greater numbers of competitors, standing crops are higher, s uggesting that there is interference as well as exploitation competiti on in our system. An experiment to investigate the effects of fish den sity on the level of movement revealed that the reported interference competition could not be attributed to increased fish movement at high er density.