What do I Look for!?
Calm down, we are getting to why you are here. I will now give a synopsis of each field mark, and explain the differences between these species. I will provide many examples of each. I have gotten all of the hard stuff out of the way now, and I will try to keep this next section in more layman's terms. I just wanted to say, toads are tricky because they are a good example of a species that is not black or white. We truly do not have a great definition for what a species is or should be.
Always think about where you are. You probably do not have a toad wildly out of known range. True, we found the furthest west population of Southern Toads in Virginia last year, but this seems to be an exception, due to geography and the little work done with Southern Toads. This is how I define these species.
American: Statewide, excluding the Eastern Shore and the far southeastern corner.
There are NO American Toads native to the Counties/Cities of Virginia Beach, Norfolk, Chesapeake, Accomack, Northampton, Portsmouth, Suffolk, Isle of Wight, or Southampton; and they are seemingly abscent from Hampton, Newport News, Sussex, Surry, and the majority of Prince George (likely present around Petersburg).
VHS has some records outside of these ranges, but without personally verifying them, I have to say they are much more likely misidentifications based on the sheer numbers of iNat reports from these areas, with none directly contradicting these ranges.
I mentioned the old "# of warts per spot" adage in the last section. The truth is this "method" is a terrible for ID because it is a side effect of a factor and not the factor. American Toads have enlarged warts and small spots, while Fowler's have big spots and small warts... Meaning, on average Fowler's will have more warts per spot than Americans. Truly old Fowler's will develope some enlarged warting on the dorsal, though its not as common to see these really old specimens. But what about the Southern? Let's not talk about it like it is a third wheel to the party, as it is too overlooked as it is. Southerns tend to have enlarged warts in big, irregular spots; but can have small spots or be patternless. Warting on the tibia/calf of the toad will be the most helpful warting to look at. Fowler's will have equal sized warting on the tibia/calf as that on the thigh. Americans will have several, much larger warts on the tibia/calf. Southern Toads will usually have a few warts on the tibia/calf that are slightly larger than on the thigh (maybe half as enlarged as Americans on average), but not always. Below is a series of photos displaying all of these traits.
The cranial ridges are a huge tool in toad ID. These ridges are typically "L"-shaped and start between they eyes and run behind the eye. In Fowler's, these ridges are often faint, and run across the top of the parotid gland. Basically, if the cranial ridge was an "L", the bottom line of the ridge will touch the parotid gland. In Americans, there ridges miss the parotid, but sometimes have a spur that points back and touches the gland. Basically, if the cranial ridge was an "L", the bottom line of the ridge will not touch the parotid gland. Adult Southern Toads have ridges similar to the American, but also usually have the presents of cranial knobs. These knobs are tall, horn-like protrusions, that are actually formed on the skull. Young individuals lack these knobs though, but generally their cranial ridges are quite "fluted" between the eyes. I will say many individuals on the northern extent of the range will often have less dramatic or even lack the cranial knobs. It also seems the adult females are the ones with the most prominent knobs.
Southern Toad showing clear knobs, yet a spotted belly from Chesapeake County where there are no naturally occurring or known introduced populations American Toads. Oddly enough this female has a dark chin as well, though it is not as transparent as that of a male.
Test Your Understanding
When you find a toad use this guide to make an educated guess. Then post your toad on iNaturalist and tag me @tysmith with a comment like “I believe this is a Fowler’s Toad because of _____.” I will happily look at the toad and answer any questions. All too often someone post an incorrect ID with no explanation to why they think it is that. This means that I really can’t tell you where you went wrong, so you are likely to continue to make the same mistakes. You can also reach out to us on our social media listed in the footer, or use our Herp ID Help Forum linked below.
I also have created a Toad Test to go with this. To really give you an opportunity to use these skills you have learned here. It and our other resources are listed below.
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