Southern Leopard Frog
Last weekend, Jasmine uploaded three photos of a frog encountered at Harmony Hill (see the previous post in this channel). This frog is one that can be a bit confusing to identify by sight, but this species is almost unmistakable by voice.
Why would this species be confusing to identify by sight? That is the most important question to answer and, when we answer that question, removing the confusion will make this frog MUCH EASIER to identify!
This species sort of looks like another species or two found in the same genus, but there are field markings that differentiate this species. This species of frog also comes in a WIDE variety of colorations, all in the brown to green spectrum. Some individuals are all brown, with spots. However, some individuals are all green, with spots. And there are quite a lot of individuals that are gradients of brownish/greenish over different parts of their bodies, with spots! AND, as if that weren’t enough confusion, the spots can be various shapes and sizes!
Now that we’ve introduced as much confusion as we can, let’s start clearing the clouded waters. Let’s look at the constants that we can look at to identify this species. Found on this species of frog are prominent, light colored ridges on each side of its back that start just behind each eye. Furthermore, there is a light band in each eye that extends onto the light ridges on the back.
Next, let’s look at the tympanum (or external eardrum) seen just below and behind the eyes. A definitive field mark to look for on the tympanum is a light-colored dot right in the middle. (I’ve included a closeup of one of Jasmine’s photos that highlight this field marking. I have placed a red arrow pointing to the dot in the middle of the tympanum.)
This species also has a pale upper lip and belongs to the family Ranidae, the true frogs.
Having covered what to look for to identify this species, that leaves one major question… Well, Josh, what is it?! It’s a Southern Leopard Frog (Lithobates sphenocephalus)! Those spots that show up on all members of this species are responsible for their common name. They’re spotted, like a leopard.
There are some who still list the scientific name of this species as (Rana sphenocephalus). It’s also not uncommon to see it listed with both genus names and have it written as (Lithobates [Rana] sphenocephalus). What’s that all about?
The older genus name, Rana, is a direct link to the name of the true frog family of Ranidae. Rana and Ranidae are different names indicating “true frogs”. The new genus name, Lithobates, is Greek for “rock walker” (Litho, meaning stone and Bates, meaning one who walks upon.) Their species name, sphenocephalus, means “head shaped like a wedge”. I’ve placed a red circle on the snout of the photo to highlight that pointed nose.
There are 8 other members of the genus, Lithobates (or still listed as Rana), in South Carolina. However, Harmony Hill is definitively in the range of two other species in this genus, Bullfrog and Green Frog. The land is potentially in the range of three other species in this genus, Carpenter Frog, Gopher Frog and River Frog.
As an amphibian, Southern Leopard Frogs are tied to water. To lay eggs and to keep their skins moist, they must be in the vicinity of water. Their eggs have to be laid in water and, with this species, that water is most likely shallow water that has little predation (usually fish). They also lay their eggs so that they’re anchored to some vegetation. However, Southern Leopard Frogs are often found quite some distance from water. While doing the snake research at Carolina Sandhills NWR, I regularly found Southern Leopard Frogs over half-a-mile from standing water. So, don’t be surprised if you encounter them away from where you might expect them!
Their diets are pretty varied, including any insects or invertebrates that might fit in their mouths. I’ve seen them munching away on crayfish. Their especially fond of crayfish that have recently molted. With that varied diet, Southern Leopard Frogs are apt to be active anytime of the day or night.
As for that unmistakable call… I’ve always said it reminds me of the sound of a balloon being twisted, much like the sound you might hear when a clown is making balloon animals. I’m attaching a YouTube video of their call for you to listen to. What do you think? Do you agree with me? Does the call sound like a balloon being rubbed or twisted to you?
No other frog in the Harmony Hill area sounds like the Southern Leopard Frog. With that in mind, this is a GREAT species to begin our toad and frog journey as we learn a little more about the Story of the Land. When you see those light-colored ridges, those dots in the middle of each tympanum, that pointed snout, those spots and when you hear that twisted balloon croak, you have Southern Leopard Frogs on the land!
As I’ve made a concerted effort to do in previous posts, I’ve also made sure to look into a species that can also be found easily in Florida. And Southern Leopard Frogs can be found throughout the Sunshine State.