| Summary: | <p>Abstract</p> <p>Background</p> <p><it>Cataglyphis fortis </it>ants forage individually for dead arthropods in the inhospitable salt-pans of Tunisia. Locating the inconspicuous nest after a foraging run of more than 100 meters demands a remarkable orientation capability. As a result of high temperatures and the unpredictable distribution of food, <it>Cataglyphis </it>ants do not lay pheromone trails. Instead, path integration is the fundamental system of long-distance navigation. This system constantly informs a foraging ant about its position relative to the nest. In addition, the ants rely on visual landmarks as geocentric navigational cues to finally pinpoint the nest entrance.</p> <p>Results</p> <p>Apart from the visual cues within the ants' habitat, we found potential olfactory landmark information with different odour blends coupled to various ground structures. Here we show that <it>Cataglyphis </it>ants can use olfactory information in order to locate their nest entrance. Ants were trained to associate their nest entrance with a single odour. In a test situation, they focused their nest search on the position of the training odour but not on the positions of non-training odours. When trained to a single odour, the ants were able to recognise this odour within a mixture of four odours.</p> <p>Conclusion</p> <p>The uniform salt-pans become less homogenous if one takes olfactory landmarks into account. As <it>Cataglyphis </it>ants associate environmental odours with the nest entrance they can be said to use olfactory landmarks in the vicinity of the nest for homing.</p>
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