Cane Toad and Gulf Coast Toad co-inhabiting in the same burrowThe Deep South Texas terrain is quite interesting. It’s mostly a delta with none to very little elevation. Hence the features of the terrain are mostly thorn-scrub, at least what is still sort of intact. The rest has become ag-land for crops or urban sprawl. The point being that there are no rock cuts, or boulders or hills or other features that are conducive to providing herps a lot of hiding spaces. As a result they’re often found around people’s houses using artificial cover.

There was one incidence when I observed a Cane Toad and a Gulf Coast Toad co-inhabiting in the same burrow. It made me wonder why they’d do so if the Cane Toad could potentially poison the gulf coast toad or even eat it. I looked around the caliche pit and there weren’t very many hiding spaces, as is the case for most of the Lower Rio Grande Valley. So, my curiosity was overwhelming and I wanted to see who was being choosy about the burrow availability.

I collected 30 Cane Toads and 30 Gulf Coast toads. With the help of a NASA engineer we designed a box with identical burrows, except one was connected to a cooler and maintained a cool 75 degrees, while the rest of the chamber was brought up to 100°F, not unusual for the region. This caused the other burrows to maintain a temperature about 10-15 degrees lower than ambient temperature, but the cooled burrow remained at 75°F. We put in pairs of toads of the same species, or one of each species all for 10 minutes at a time, never using the same toad twice during one trial. We had infrared cameras set up to look inside the burrows and digital cams above recording their movements.

We found that Gulf Coast Toads will enter any hole they can inhabit to escape the heat, but Cane Toads, explored all available holes and 90% of the time chose the cool burrow. The other 10 percent of the time they chose burrows that already had a toad inside. We presented this work at the Joint Meeting for Ichthyologists and Herpetologists. The reason for this I believe is that by being in close proximity to another toad they reduce surface area and hence decrease desiccation. Another advantage is that if the “other” toad expels some water onto the substrate both the Cane Toad and the Gulf Coast toad can re-uptake it. Cane toads were sort of using the other toads as living canteens if you will, because they’re just bad-asses and excellent problem solvers.