PATH INTEGRATION IN DESERT ANTS. APPROACHING A LONG-STANDING PUZZLE IN INSECT NAVIGATION

SUMMARY The most dominant ant of the Saharan salt pans, Cataglyphis forth (Forel) (Hymenoptera Formicidae), is a long-distance forager leaving its underground nest for distances of up to 100–200 m. While foraging, each individual ant continually keeps track of its own position relative to home by using a path integration (dead reckoning) strategy. It has generally been assumed that path integration in animals relies on some kind of trigonometric computation (vector-sum hypothesis), but critical experiments for scrutinizing this hypothesis have been neither performed nor designed. Here we consider an alternative hypothesis according to which the animal uses some non-trigonometric formalism to closely approximate its homeward course (mean-direction hypothesis). This hypothesis is not a post hoc model deduced from experimental work, but a predictive hypothesis designed to inspire a new experimental approach. First, we describe the kind of systematic error that would result from the most simple kind of comput...