How to Know a Frog’s Gender

If you have ever tried looking at a frog to guess if it is male or female, you probably realized it’s pretty difficult. It is almost impossible to tell whether a frog is male, female, or hermaphrodite because its reproductive organs are internal, so determining a frog’s gender can be complicated. However, there are characteristics unique to each frog species that will help you differentiate frog gender.

As a general rule, ways to determine if a frog is male, female, or both include species, appearance, size, color, mating behavior, and vocalizations. Male and female frogs look similar as their reproductive organs are internal and cannot assist in determining gender unless the frog is dissected.

Figuring out whether a frog is a male, female, or both is less complicated once you determine the species. Learning what characteristics are unique to each gender will help you sort out gender. Keep reading to learn what features will help you determine frog gender as a general rule, and more specifically for certain species.

How to Generally Determine a Frog’s Gender

If the usual visual cues to determine a frog’s gender aren’t obvious, it turns out that some generalities can help you make this determination. However, knowing what type of frog or the species and understanding the differences between the sexes is the best way to tell (more on that below).

The general characteristics and behaviors that can help you tell male frogs from female frogs are:

Size: Female frogs are generally larger than male frogs
Mating rituals: Males are on top of females while mating
Sounds: Male frogs generally have vocal sacs to call females

All this information is helpful, but if you really want or need to pin down the gender, let’s have a deeper look at how to determine the sex more accurately. Here is a helpful table showing various attributes of a frog’s appearance and how they differ between the sexes:

Trait	Females	Males
Size	Females are generally larger than males	Males are generally smaller than females, making it easier to climb up on the female’s back during amplexus.
Color	In many frog species, the male and females share the same color.	In some frog species, males change color during mating season.
Skin	Female frogs generally have smoother skin and do not have any texture.	If there is texture to a frog’s skin, such as bumps, fringe, or spikes, it’s generally a male (except for toads which could be either).
Sounds	Female frogs can make noise; however, vocalization is a trait where the males excel. An exception to this is the Emei music frog from southwest China.	Male frogs are more vocal, and a vocal sac will be visible. A vocal sac is a thin membrane located on the underside of the neck that facilitates making sounds like croaking.
Ears	There is an ear covering called a tympanum. On females, this disc is the same or smaller circumference as her eye.	The tympanum of ear covering on a male is generally bigger than its eyes.
Appendages	Female frogs generally do not have pads or patches on their toes. There are a few species that have a fringe used to help in nest making.	Some males have pads, rough patches, or larger toes during mating season designed to help the male grip the female more effectively during amplexus.
Reproduction	Generally, females are on the bottom of a reproductive couple’s amplexus to lay eggs.	Generally, males are on the top of a reproductive couple during amplexus to fertilize eggs.

But you may have noticed above that we said some frogs are hermaphrodites, meaning they have both genders. Let’s explore this in more detail.

Some Frogs Have Both Genders

Some frogs may be hermaphrodites, intersex, or experience sex reversal. This can happen due to the presence of pesticides (Hayes et al, 2010) but may also be “a relatively natural process in amphibians” (Lambert, 2019).

“While sex reversal and intersex are often considered aberrant responses to human activities and associated pollution, we found no such associations here. Our data perhaps begin to suggest that, relative to what is often suggested, sex reversal may be a relatively natural process in amphibians.”
Lambert et al (2019)

It is much harder to identify an intersex frog, however, some frog species are more prone to having a high number of intersex individuals. If you are interested in learning more about intersex frogs and the difference (and amalgamation in media) with “gay frogs,” definitely check out our essay on the topic.

Let’s have a closer look at specific frog species since it is easier to determine gender when you know the type of frog at hand.

Identifying Male and Female Frogs Across Species

You must be excited to put your newfound knowledge about determining whether you are looking at a male or a female frog to use. Let’s look at a few specific examples to see the actual differences between different frog genders depending on the species.

African Dwarf Frogs

The African Dwarf Frog is a species where the males and females look so similar it is difficult to tell them apart. However, there are key features that can help you figure out the genders:

When mating or when excited, the males of this species hum or sing.
The females are generally larger and when they are ready to mate, exhibit more of a pear shape, indicating they are laden with eggs and ready to mate.
If you look closely at the back of the male’s front legs and hands, there is a small white bump or black patch that is a gland thought to be helpful during mating.
Males are generally smaller and have slimmer bodies than females.

African Dwarf Frogs are known to be either born hermaphrodites, intersex, or experience sex reversal. This is one of the reasons why they are often studied by scientists when it comes to gender in frogs (Hayes et al 2010). However, it is difficult to observe intersexuality in frogs without scientific dissection (do not do this yourself) or observing African Dwarf Frogs over a certain period of time (CTNF).

Australian Tree Frogs

To tell a male Australian Tree Frog (also known as White’s Tree Frogs or dumpy tree frogs) from a female, you’ll need to have a close look at two distinctive features:

The vocal sac on the male will present as dark and larger generally due to frequent calling, especially during mating season.
The appendages (toes) on the male’s forearms will have pads on the thumbs that darken before mating.

Generally speaking, female tree frogs of this species are larger than the males but to be sure, look for the traits listed above.

American Bullfrogs

The iconic American Bullfrog is also a frog species where the males and females look very similar. The key features used in distinguishing the male Bullfrog from the female Bullfrog are:

For females, the external ear covering, or tympanum is about the same size as her eye whereas, for males, their tympanum is generally much larger than their eye.
If you can compare the throat color of Bullfrogs, you’ll notice the males have a bright yellow throat and the females have a creamy white throat.
The females of this species are not vocal; most of the vocalization you hear is a male.

Bullfrogs are a prime example of using the tympanum to distinguish between the genders, and of course, the croaking, grinding, and chirping sounds definitely signify male frogs.

More About Frog Gender

In summary, even though it can be difficult to tell the gender of a frog, there are clues or characteristics you can look for to tell the difference once you determine the species. And once you know what to look for, you’ll have no trouble figuring out who’s who!

Check out these other articles on our site that cover frog reproduction, gender, and sexual orientation in more detail:

Sources

Hayes, Tyrone B et al. (2010) “Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis).” Proceedings of the National Academy of Sciences of the United States of America vol. 107,10: 4612-7. doi:10.1073/pnas.0909519107

Lambert, Max & Tran, Tien & Kilian, Andrzej & Ezaz, Tariq & Skelly, David. (2019). Molecular evidence for sex reversal in wild populations of green frogs (Rana clamitans). PeerJ. 7. e6449. 10.7717/peerj.6449.

National Audubon Society. Field Guide To Reptiles & Amphibians, (2008), pp: 701 & 704; Alfred A. Knopf, 24th Printing.

New York Government, Frogs