Slit in a Nest Site Influences the Nest Site Selection in Cavity Nesting Ant Colonies

For ants, nests provide a refuge against predators and protection from environmental factors. Thus, choosing a good nest site is important for an ant colony, but nest sites are limited resources. Ants of the genus Temnothorax inhabit small cavities in, e.g., acorns, twigs and under rocks. Earlier, it was shown that the ants are able to choose a superior site. In this study, using binary choice tests, we studied the nest site selection by Temnothorax crassispinus ant colonies that typically inhabit empty acorns. For this purpose, we used artificial nest sites without and with an additional slit in the nest wall, mimicking the cracks in potential nest sites under natural conditions. We found that the ant colonies preferred artificial nest sites without these slits. However, no difference in the number of colonies inhabited nest sites with a slit vs. those without a slit was found when the slits were closed using transparent food foil, which prevented the air flow while keeping an inflow of light. What is more, additional light through the hole in the red filter covering the artificial nest sites had no influence on the nest site selection. The results of this study suggest that the air flow through a slit in the nest site wall, rather than additional light, influences the nest site selection. The absence of cracks, e.g., in acorns, could be an indication of the durability of potential nest sites. Thus, choosing a cavity without such damage could be beneficial for the ant colonies.