Feature

Anaxyrus houstonensis: A Dying Breed with a Familiar Name | Houston’s Zoo No. 06

I’M not writing an article about a species because I’m also writing a paper on that same species! YOU’RE writing an article about a species because you’re also writing a paper on that same species!

Okay, fine. This week, I’m talking about an endangered toad precisely because I’m in the middle of writing a review paper on it for Dr. Distel’s herpetology class. Don’t worry, though. The tone here is going to be very much different. I’m not so sure a conversational writing style would reflect well in my grade…

I selected the Houston Toad (Anaxyrus houstonensis), not because of the name—although that is a cool coincidence—but because I happen to be very familiar with the conservation organization who are working their hats off to bring the Houston Toad back from the brink of extinction: Houston Zoo, Inc. As my friends and readers know, I have volunteered for the nonprofit in question for a good five years now, and that experience gave me a lot of great information on these critically endangered animals.

The Houston toad is not a particularly large toad (2-3.5 inches or so), nor is its appearance particularly striking. Like many toads in the family Bufonidae, they range in color from brown to reddish brown to yellowish… brown, and have variable dark spots on their legs and back. As a matter of fact, it’s difficult, for many people, to tell the difference between the Houston Toad and the non-endangered Gulf Coast Toad (Incilius nebulifer) without proper training.

It’s not impossible, though. There are a few key field marks that distinguish one from the other. First, if you happen to be looking at males, the Houston Toad’s throat will appear blueish gray, while the Gulf Coast Toad’s will be the same shade as the rest of its belly.

Second—and this goes for both sexes—the belly on a Houston Toad is typically more spotted than a Gulf Coast Toad’s, which is most often a uniform sandy brown.

The most useful thing to look for, though, is a set of fleshy structures called the cranial ridges. These ridges are located on the top of a toad’s head, between its eyes. They are particularly useful in identifying species because they don’t vary between individuals. Basically, every Houston Toad has the same-shaped cranial ridges, and they are distinctly different from the ridges of the Gulf Coast Toad. To describe it simply—and I’ll include an image to try and better illustrate this—a Houston Toad’s ridges are shaped like the letter ‘L,’ and the Gulf Coast Toad’s are shaped like the letter ‘Y.’ See if you can see what I mean:

Above: A. houstonensis; Below: I. nebulifer

All this to say that there is not much that sets A. houstonensis apart, physically, from its amphibian allies. The few distinct features it does have are so slight, you have to know what to look for to even see them.

So, you may be wondering, if the two species are so similar, why does the Houston Toad need saving, while the Gulf Coast Toad is of least concern? Is there some secret advantage that the Gulf Coasts have that the Houstons don’t? No. Not really.

The simple truth is, Gulf Coast Toads aren’t picky about where they live. At all. I remember when I was in scouts, and working on my Reptile and Amphibian Study merit badge, I monitored a group of Gulf Coast Toads that had taken up residence under a rock next to my sidewalk. They can thrive everywhere from the woods to the suburbs, and the humid swamps of Brazoria county to Kerrville’s dry, rocky hills.

The Houston Toad is a different story. They require all of the following: loose, deep, sandy soil; heavy canopy cover from the trees, but an open understory; bunch grasses under which they can take cover; and, of course, a stable water source for breeding.

That is what you might call a tall order, especially in the Houston area. If there’s one thing the city of Houston is good at—that the Schreiner student of the same name is regrettably not—it’s building itself up. “The City with No Limits” has expanded so much that the Houston Toad has beed eradicated from Harris, Fort Bend, and Liberty counties, where it once thrived. It is now restricted to a few small areas, well to the west of the metropolitan area.

Organizations like the Houston Zoo are doing very well with breeding Houston Toads in captivity for release, and numbers are improving as an effect of their efforts. It’s a difficult task, but it’s slowly beginning to pay off, and this little Texas native is doing its best to make a comeback.

I always say you should go and read more on whatever critter I’m presenting, but in this case, it’s even more imperative that you do. An animal unique to Texas is in danger of disappearing for good, and it’s up to us to try and keep it around awhile longer. I’d hate to see what kind of domino effect would occur in the east Texas food chain if these toads were wiped out.


That’s all from me. If you have any questions, or would like to request an animal to be featured, comment down below and It’ll be my pleasure to help you out.

See you next weekend, and until then I am…

As I ever am.

Categories: Feature

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