Abstract: Falling from branches and vines can leave wingless worker ants living in Neotropical tree canopies in unfamiliar and dangerous territory on the forest floor. Therefore, we expect that worker ants avoid foraging on substrates that interfere with their adhesive locomotor performance (i.e. walking, running on horizontal and vertical substrates). However, there is scant direct evidence that foraging ants avoid substrates known to challenge their adhesive locomotor system. The purpose of this study is to test if worker ants choose to forage on substrates that support or impede their locomotor performance. Specifically, we compared foraging behavior and locomotor performance on wooden dowels, which engage ants attachment structures (i.e. adhesive pads, tarsal claws), to glass rods, which only engage adhesive pads and are often more slippery to move across. Dowels were placed near active ant foraging trails and baited with a food reward. We recorded ant response to both experimental surfaces and compared this to locomotor performance in lab under similar conditions. We found that ant colonies invested more total foraging time on baited wooden dowels than on baited glass rods. Colonies also invested more foraging effort in whichever bait they discovered first, regardless of experimental surface. Preliminary results suggest that, in lab, ants were more likely to fall from a glass rod than from a wooden dowel but ran more quickly on glass than on wood. We conclude that ants preferentially forage on substrates that allow them to engage both their adhesive pads and tarsal claws. However, traveling on these substrates may decrease locomotor efficiency in other ways. Our results suggest that foraging ants make choices about where and how to forage based on safety from falling and foraging efficiency (i.e. returning to known food sources rather than searching for other, more accessible food sources).
