Tuesday, March 31, 2020

Natural History: Southern Toad (Anaxyrus terrestris)

Hey everyone, hope life is not becoming too boring while we all suffer house arrest together. I sadly have to keep working during this crisis, but one benefit is coming home in the evening when many of our local amphibians like to start coming out to say hi because many are nocturnal. This little guy was sitting outside on the driveway around 8 PM on John's Island, I was able to pick him up and get quite a few pictures before he became to anxious to hold any longer. As mentioned in the title, I believe this to be a male southern toad (Anaxyrus terrestris), approximately 2-2.5 inches long, in the adult phase of his life cycle. By looking at these pictures, you can see his external vocal sac, which helps determine the sex, because in most species of anurans (frogs/toads) only the male has a vocal sac. Also seen in these pictures are the large ridges on top of the head with the large knobs present on the bottom of these ridges which are one defining characteristic of the species A. terrestris. What was so fascinating about observing this little fella was that there were many different species around us making calls, being the beginning of spring these could be the start of mating calls, he began to call while in my hand. I'm unsure of how common this is, but to me, whether him trying to mate, warn others, or ask for help, the fact he began making his call while I was holding him astonished me. It was lower in frequency then typically observed, possibly because of my finger placement around his diaphragm, but nonetheless something to behold as my hand shook with vibrations. Such a small toad was able to produce enough vibration to make my fingers visibly shake. Once he began making his calls though, I knew it was time to return him to his home, the bushes and tidal creek that makes up our backyard. This was a cool experience and I would encourage everyone to go and observe/listen for your local amphibians as they begin to enter mating season, when I personally think most animals become the most intriguing because of what they will do to find that mate and keep the competition away. Stay home, but still get enough fresh air to remember that life is beautiful and always finds a way to conquer the unimaginable!




2 comments:

Anonymous said...

I really enjoyed reading your post! I wonder if this Southern Toad began to produce sounds while you were holding him as a potential call for help?

Allison Welch said...

The release call! Male toads aren't very discriminating when it comes to what they will amplex, so they've evolved this release call as a way to startle something that has grabbed them. It's a distinct sound from the advertisement call, more of a buzz and, yes, quite a vibration. (Stay tuned for our upcoming lecture on respiration, where we will be reminded that amphibians lack a diaphragm!)