The Surprising Communication Skills of Bullfrogs: More Than Just a Moo

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Bullfrogs are fascinating amphibians with an impressive repertoire of sounds. Their name comes from the male’s deep, resonant “mooing” call, which sounds a lot like a cow or bull. However, the weird and upsetting sound made by the bullfrog in this video from Mark Roe’s YouTube channel is far from the usual baritone mooing. Why do bullfrogs scream like that? And how do they even do it?

Why Do Bullfrogs Scream?

Bullfrogs are rather chatty animals who use a whole range of sounds to talk to each other. An “advertisement call”, for example, is how male bullfrogs serenade and attract mates. An “alarm call“, on the other hand, is commonly used by younger frogs when they’ve escaped danger. But of all the sounds a bullfrog can make, the “distress call” is probably the most unique  — and unsettling.

Bullfrogs emit distress calls when they are caught by predators. These high-pitched screams are likely meant to shock the predator (or whatever is trying to grab them). Essentially, it’s like a bullfrog’s panic button, screaming “Let me go!” Which is exactly what we hear in the video above. When the child picks up the bullfrog, the poor thing becomes super stressed out, as if caught by a predator. Bullfrogs only scream like that when they are extremely scared  — typically when they’ve been captured or picked up. They are not fans of being handled, even by a small child.

Both male and female bullfrogs scream with their mouths wide open, just like the frog in the video. It makes sense why bullfrogs scream, right? Even some humans scream when they’re in danger. But the real question is, how do bullfrogs physically produce such a crazy sound?

How Do Bullfrogs Scream?

Bullfrogs make various sounds with their respiratory systems. They force air back and forth across their vocal cords, which causes them to vibrate and produce sound. Male bullfrogs also have a vocal sac to help amplify the sound.

Stress plays a huge role when it comes to a bullfrog’s impressive screaming skills. The more stressed a bullfrog is, the harder it forces the air across its vocal cords. That’s why their distressed screams are so loud and high-pitched.

However, it’s not just about force; stress also triggers hormonal changes. When a bullfrog gets super stressed — like when it’s captured or held  — its body releases hormones like cortisol. This can make the frog’s muscles tense up, changing how it breathes. This then affects how the air moves across the frog’s vocal cords, changing the sound they produce.

Where Do Bullfrogs Live?

The bullfrogs captured in the video above are most likely American bullfrogs (Lithobates catesbeianus). Native to North America, these massive frogs can grow more than 8 inches long and weigh up to a pound and a half.

American bullfrogs are found all over the continent, from Canada down through the United States and even into Mexico and Cuba. They live in freshwater habitats with still or sluggish water, like the edges of ponds, streams, marshes, and lakes. Sometimes you can even spot bullfrogs relaxing in abandoned swimming pools.