There’s something primal and unforgettable about the sound of a swamp at night. The buzz of insects, the croaks, chirps, trills, and barks, these aren’t just background noise. For those of us who live for herping, these calls are a living soundtrack that tells us exactly who’s out there, even when we can’t see them. Identifying amphibians by their calls is one of the most rewarding (and useful) skills you can develop as a field herper. Whether you’re waist-deep in a Southern bayou, crouched beside a mountain stream, or standing near a roadside ditch after a rainstorm, the sounds of frogs and toads can guide your next move better than any flashlight.

Why Learn Amphibian Calls?
Frogs and toads are often more heard than seen. During the breeding season, many species call out with impressive volume—some even rivaling a chainsaw in decibels. But their camouflage and shy behavior make them tough to spot. Being able to recognize their vocalizations lets you know which species are present in an area, even if they never show themselves.

Plus, it just makes field herping a lot more satisfying. There’s a thrill in hearing the raspy quack of a Wood Frog or the sharp “peep!” of a Spring Peeper and knowing exactly who you’re listening to. It turns a walk in the dark into an interactive experience—like tuning in to nature’s version of a roll call.

Anatomy of a Frog Call
Frogs and toads produce sound by pushing air from their lungs through their larynx and vocal sacs. These vocal sacs can inflate like balloons, amplifying the sound. Each species has a unique call that varies in pitch, duration, rhythm, and volume. These calls are often tied to mating, males are doing their best to impress females, and each species has a “song” she responds to.

There are different types of calls, too:

• Advertisement Calls – used to attract mates and defend territory
• Release Calls – given when a frog is mistakenly grabbed by another male
• Alarm Calls – rare, but used when a frog is threatened

Common Calls You Should Know

Here’s a breakdown of some of the most iconic calls from across North America. Keep in mind that many of these can be heard during spring and early summer, especially after heavy rains:

• Spring Peeper (Pseudacris crucifer): A high-pitched “peep” that repeats quickly. Think of a smoke alarm chirp on loop. Tiny frog, big voice.
• American Toad (Anaxyrus americanus): A long, musical trill that can last 20–30 seconds. It’s like someone running a finger around the rim of a wine glass.
• Green Frog (Lithobates clamitans): Sounds like a banjo string being plucked: “gunk!”
• Bullfrog (Lithobates catesbeianus): Deep and resonant: “jug-o-rum.” If there’s a bass section in the frog choir, it’s the bullfrog.
• Southern Leopard Frog (Lithobates sphenocephalus): Chuckling croaks, almost like someone laughing underwater.
• Gray Treefrog (Dryophytes versicolor): A short, bird-like trill that sounds buzzy and melodic at the same time.

Pro Tips for Identifying Amphibians by Call

• Pay attention to patterns – Is it a single note or a trill? Fast or slow repetition?
• Consider the time and location – Different species call in different habitats, temperatures, and times of year.
• Use binoculars with a flashlight – Sometimes you can spot the vocal sac expanding, which helps confirm your ID.
• Watch for overlapping calls – In choruses with multiple species, isolate calls by mentally focusing on one sound at a time.

The next time you’re out in the field, don’t just keep your eyes peeled, tune in with your ears. The swamp, the pond, the puddle, and even your backyard ditch might be alive with amphibian conversation. Learning their language adds a whole new level to herping, especially for those who appreciate the quieter details of nature.

So throw on your boots, grab a headlamp, and head into the night. The symphony of the swamp awaits, and it’s calling your name.