Fear in a handful of dust: experimental evidence for substratum segregation between geckos with different adhesive toe pad configurations on Giraglia Island, Corsica.

A colour-coded acrylic mark was applied to allow individual identification. Subsequently each lizard was acclimated for three days in individual terraria. Throughout the experiment, the temperature and light conditions were the same as those of the ambient external environment.

The geckos were fed <i>ad libitum</i> with moths, spiders, or cricket larvae daily. Twice a day water was sprayed into the terraria, allowing the animals to drink.</p><p dir="ltr">An experimental arena measuring 50x30x36 cm (length x width x height) has its interior vertical surfaces covered with equal areas (one long and one short wall each) of mildly powdery prasinite from Giraglia island and slate used for roofing (Fig. 5A).

Slate was chosen because it has a smooth surface with few irregularities and is not powdery. The glass floor of the arena was covered with sand to make the surface uninviting for the geckos. The transparent polycarbonate ceiling, onto which geckos never ventured during the course of the experiment, allowed for observation.</p><p dir="ltr">Observation bouts lasted for 30 minutes.

At the commencement of each bout, each tested individual (Table 1) was carefully placed onto the sand-covered floor at the centre of the experimental enclosure and allowed to move off this surface and acclimate for 30 minutes prior to observations being recorded. For the subsequent 30 minutes the position of the gecko was recorded at one minute intervals and categorized as being on 'prasinite’ (Fig. 5B), 'slate' (Fig. 5C), or 'both/floor' (i.e. bridging between the two surfaces or on the floor), for a total of 30 recorded positional observations per bout.

It was also noted whether the animal had moved or remained stationary since the previous observation, and if it had moved, on which substrate this occurred. For each 30-minute test session, the scores for these observations were tallied for each individual. The time of day at which these bouts were conducted for each individual was varied to include both diurnal and nocturnal observations (Supplementary material).

The orientation of the experimental enclosure was varied by rotating it 180° each time a new gecko was introduced. This meant that the long prasinite wall that faced west was reoriented to face east and vice versa. Once the experiments were complete all test individuals were released at their original site of capture.</p>