Chemical cues may allow a fossorial amphisbaenian reptile to avoid extremely saline soils when selecting microhabitats

When selecting optimal habitats, animals should rely on detecting environmental cues that indicate the suitability of a given site. In fossorial animals, restrictions of the underground environment might limit the opportunities for habitat selection. However, field observations of some fossorial amphisbaenian reptiles indicate that microhabitat occupancy is not random. This might simply result from the low survival of individuals in suboptimal habitats, but it may reflect active behavioral selection. We suggest that, in the fossorial environment, chemical cues may be very important for actively selecting or avoiding specific microhabitats. Here, we tested the ability of Trogonophis wiegmanni amphisbaenians to discriminate and select different types of substrates by using chemical cues alone. In laboratory preference tests, amphisbaenians selected soils with low salinity levels (natural or experimentally manipulated), mimicking the microhabitat selection patterns observed in the wild. Moreover, chemosensory tests measuring tongue-flick rates showed that amphisbaenians discriminated using chemical cues alone between soil types according to natural salinity levels, and also between manipulated chemical stimuli with different salinity levels. These results suggest that the microgeographic patterns of distribution of these amphisbaenians are due to their ability to use substrate chemical cues to actively avoid extremely saline soils. and select optimal microhabitats.