How to Tell If a Tree Frog is Male or Female: Expert Guide


Determining the sex of a tree frog is an important skill for amphibian enthusiasts. Whether you are a backyard pond owner observing wild tree frogs, a student researching populations, or a breeder managing captive frogs like the popular White’s tree frog, differentiating between males and females allows better understanding and care.

This guide covers key physical traits, behaviors, and examples across various tree frog species to help with identifying, comparing and sexing males and females accurately. While casual observers can develop a keen eye for spotting differences, examination by expert herpetologists provides the most reliable results.

We’ll discuss distinct characteristics of male tree frogs, including expanded vocal sacs used to amplify alluring mating calls to prospective females. We’ll also explore mating rituals, nesting behaviors, size variations between the sexes, and case studies across North American green tree frogs, Amazon milk frogs, and those common in home terrariums.

Follow along as we cover actionable tips on:

  • Recognizing when male tree frogs are ready to mate
  • Hearing differences in male and female mating calls
  • Feeling for physical traits like nuptial pads on a male’s fingers
  • Observing nesting behaviors to spot the female frog

Properly differentiating between male and female frogs assists with:

  • Managing captive breeding populations
  • Collecting accurate data on wild amphibian species
  • Appropriate care as pets or wildlife

Let’s explore the wonderful world of tree frog gender identification! The rewarding experience both deepens one’s passion for herpetology while contributing to conservation efforts.


Key Physical Characteristics of Male Tree Frogs

When seeking to identify whether a tree frog is male, look for these distinctive characteristics not found in females of the same species:

How to Tell If a Tree Frog is Male or Female

Expanded Vocal Sacs

The most telling sign is to observe or listen for a male’s mating call. Male tree frogs attract females by expanding a vocal sac located under the throat and amplifying alluring “croaks”. The air-filled sac serves as a resonance chamber that can swell to up to three times larger than the female’s.

For example, when a popular pet like the White’s tree frog is ready to breed, the male emits a distinct “craw-eck” barking noise. Compare to the higher pitched “quacking” noise that a female White’s tree frog makes. This frog’s vocal sac may also change color during mating season as hormones shift.

Accentuated Nuptial Thumb Pads

Examine a male tree frog’s “fingers” closely and you may observe darkened pigmentation or roughened skin pads used to grasp the female during amplexus mating position. These accentuated nuptial pads are especially pronounced right before breeding season.

Carefully handling the frog to spread its fingers, feel for these tactile differences between male and female thumb pads. You can also spot scrubby prepollex projections near the male’s inner thumbs. Females lack these temporary pads and skin projections used for mating grasps.

Smaller Size vs Females

Mature male tree frogs are generally smaller than mature females of equivalent age within the same species. However, significant size overlaps can exist. Use relative size comparisons when possible by examining known males and females side-by-side rather than relying solely on growth charts.

For example, northern cricket frogs and Pacific tree frogs demonstrate definite size dimorphism. But a substantial range in lengths and weights means measurement alone doesn’t dictate sexing the frog. Best practice is combining multiple indicators.

Identifying Distinct Traits of Female Tree Frogs

While less showy than their male counterparts, female tree frogs have key physical and behavioral characteristics that differentiate them once you know what to look and listen for.

Distinct Traits of Female Tree Frogs

Larger Adult Size

Mature female tree frogs are most often larger than mature males of the equivalent age within the same species. Use relative size, comparing a frog of unknown sex against a confirmed male or female adult frog if possible.

While measurement charts provide guidance on average sizes, significant variation exists. Relying solely on a tree frog’s length or mass doesn’t provide foolproof sex identification. Combine with other indicators like breeding season behaviors.

White Underside Throat Color

In tree frogs like White’s tree frog, the female exhibits a lighter throat coloring compared to the male’s darker pigmentation. The hue can shift from white to a pale yellow, especially prior to breeding season.

Shine a light upwards under the frog’s head to better see this underside throat color distinction. The brighter hue often connects to the abdomen underside as well.

Absence of Expanded Vocal Sac

Listen for the unique mating call of a male tree frog, characterized by a resonant croak or bark amplified by vocal sac air chambers. A female lacks this adaptation and makes significantly less noise. She may produce a short muffled sound in response to the male.

For example, compare the louder repetitive “ribbit” of the male red-eyed tree frog calling out to attract a mate against the inconspicuous female. Combining auditory cues and visual coloration provides reliable signals.

Contrasting Mating Behaviors Confirm Sex

Observing tree frog breeding rituals and early rearing behaviors can further validate whether you’ve accurately differentiated males from females.

Contrasting Mating Behaviors Confirm Sex

Amplexus Mating Position

A dead giveaway male tree frog is one observed clasped onto another frog’s back in the amplexus mating position. This specific posture features the male grasping the female with his forearms behind the armpits of the female while straddling her back.

The male will remain clasped in position for hours or days before the female lays the fertilized eggs. This extended amplexus mating dance is not seen outside of courtship and breeding interactions.

Laying and Guarding Egg Clutches

Meanwhile, the key behavior indicating an adult female tree frog is discovering her deposited cluster of eggs. Tree frogs tend to lay eggs communally in ponds and puddles rather than scattering solo.

Observe if the frog floats in the water across the egg mass, fanning her back legs over the clutch to ensure adequate oxygen circulation for development. She will often linger to guard the offspring through initial tadpole stages.

Rearing Tadpoles on Back

Another telltale female indicator is witnessing advanced transporting of hatched tadpoles after her frogspawn hatches. Several tree frog species exhibit dorsal transport where the female allows her early-stage tadpoles to embed and develop on her moist back for days.

Watch for a cluster of tiny wriggling black tadpoles situated on the adult tree frog’s back if uncertain of sex. Males do not display this distinctive maternal rearing behavior.

Case Studies: Sexing the Amazon Milk Frog and Green Tree Frog

While techniques covered apply broadly across tree frogs, observing key traits in specific species can further validate accurate differentiation.

Determining Sex in the Amazon Milk Frog

The South American Amazon milk frog demonstrates strong sexual dimorphism between females and males:

  • Females reach lengths of 7 inches, substantially larger than the 3 inch male
  • Listen for the repeating high-pitched “skeek skeek” mating call from the male
  • Contrast against the female’s sporadic short low croaks
  • Notice the adult male’s yellow lip spot absent on the female
  • Watch for the female wandering with tadpoles later clinging to her back

Sexing the North American Green Tree Frog

The small bright green frogs native across the Eastern United States also exhibit reliable signals:

  • Shine a light up at the throat to see the female’s white or pale yellow hue
  • Compare to the male’s bright yellow throat when calling to mate
  • Notice the male’s darker yellow nuptial pads on his thumbs
  • Listen for the longer rattling “craaawk” mating call from the male
  • Watch for him grasping the female’s abdomen to fertilize eggs

Carefully observing species-specific traits such as coloration, growth size, calls, and breeding behaviors allows accurate identification of male and female frogs.


Learning how to differentiate male tree frogs from females by observing key physical characteristics, mating behaviors, and species-specific attributes has important applications.

Properly sexing frogs helps create appropriate habitat enclosures and care when keeping popular pets like White’s tree frogs. Identifying gender in wild amphibians assists field herpetologists assembling census data on declining tree frog populations to support conservation efforts.

Combining tactics like:

  • Spotting nuptial pads on male thumb tips
  • Comparing relative size against known adults
  • Listening for mating calls amplified by the male’s vocal sac
  • Feeling for physical differences in throat skin texture
  • Watching for amplexus mating positions

Allows accurate differentiation. Consult an expert exotic veterinarian or amphibian specialist if still uncertain after following the tips outlined.

While casual observation can provide hints, examination by experienced amphibian handlers usually delivers the most reliable tree frog gender identification. Contact area zoos, university biology departments, wildlife educators, or government conservation groups to have unknown frog samples assessed.

Proper identification leads to better breeding outcomes for captivity, supports disciplines like herpetology, and informs protection of delicate frog ecosystems – helping stabilize and sustain vulnerable amphibian populations.


Q: How can you tell if a tree frog is male or female?

A: Male tree frogs are usually smaller than females, and they may have a swollen finger. Female tree frogs can have white throats, especially during the breeding season.

Q: Do male and female frogs look different?

A: Yes, in some species, males and females may have different physical characteristics. For example, female tree frogs may have lighter or whiter throats compared to males.

Q: What is the main way to identify a male frog?

A: Male frogs are generally smaller than females. They may also have a swollen finger or emit a different croaking sound.

Q: Can you determine a frog’s sex by its croaking sound?

A: Yes, in many frog species, males call out to attract females during the breeding season. The croaking sound and frequency can help differentiate male and female frogs.

Q: How can you tell if a frog is a male by its behavior?

A: Male frogs sometimes exhibit specific behaviors like calling or hopping onto another frog to mate during breeding seasons, which can help identify their sex.

Q: Are there any other physical differences between male and female frogs?

A: In some species, male frogs may be heavier or larger than females, but this can vary depending on the specific type of frog.

Q: Can tree frogs change their gender?

A: Some frog species have the potential to change their sex in response to environmental factors or mating dynamics, but this is not common in all frog species.

Q: Do male frogs like to be touched?

A: While individual preferences may vary, most frogs, including male frogs, may not enjoy being touched or handled as they are sensitive amphibians.

Q: What is the best way to sex a pet frog?

A: If you are unsure of your pet frog’s sex, it’s best to observe specific physical characteristics or behaviors, such as size difference, croaking sound, or mating behavior, to determine its sex.

Q: Do all species of frogs exhibit clear indicators of their sex?

A: Not all frog species have easily identifiable physical differences between males and females, and in some cases, it may require close observation or expert knowledge to determine a frog’s sex.

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