Noise-Making Animals

In nature, sound is a fundamental tool for communicating, warning, attracting a mate, or intimidating. We generally distinguish:

• Singers: birds, whales, frogs, capable of producing harmonic sounds thanks to vocal cords or specialized organs such as the syrinx.
• Callers: certain primates, birds of prey, or deer, which emit powerful calls to signal danger or defend a territory.
• Noisemakers: these animals use specific body structures to generate sound without vocalizing.

We’ll focus on this last category, because it includes fascinating mechanisms, often comparable to natural musical instruments.

Noisemakers’ sound-producing techniques

Noisemaking animals generate sound thanks to specialized structures that allow them to strike, rub, or vibrate. Here are a few examples:

• Stridulation: used by grasshoppers and crickets, which rub their wings or legs against each other to produce a continuous sound.
• Percussion: the European green woodpecker drums on tree trunks with its beak, while the beaver slaps its tail violently on the water to warn others.
• Cavitation: the pistol shrimp creates an ultra-fast air bubble that collapses with a deafening crack, capable of stunning its prey.
• Muscle-driven vibration: cicadas vibrate a rigid membrane in their abdomen (the tympanum) to produce a piercing song.

The club-winged manakin

A spectacular example is the club-winged manakin (Machaeropterus deliciosus): instead of singing, the male produces a mechanical note by rubbing modified feathers at extremely high speed, like a true living miniature instrument. It therefore produces stridulation. If this intrigues you, I explain it in detail here: The bird that plays its wings.

The rattlesnake: a unique biological resonator

Among these noisemakers, the rattlesnake (Crotalus) is an exceptional case. Unlike the others, it doesn’t rub, strike, or contract any muscle to produce sound. It uses a rare acoustic mechanism in the animal kingdom: a dead biological structure attached to its body.

Its rattle is made of keratin rings (like our nails), which accumulate with each shed. When it shakes its tail at high speed, those rings collide, producing the characteristic buzzing sound. This system works like a mechanical resonator, amplifying the sound without requiring any other interaction.

This phenomenon is unique because it relies on inert material. Most animals generate sound with active structures (muscles, membranes), whereas the rattlesnake vibrates a rigid structure that functions like a natural rattle.

Why these noises?

The sounds produced by these animals serve essential functions:

• Intimidation: the rattlesnake uses its sound to deter predators without attacking.
• Communication: animals stridulate to attract a mate or warn of danger.
• Hunting: the pistol shrimp stuns its prey with a sharp snapping sound.
• Territory marking: the European green woodpecker drums to signal its presence.

Evolution has shaped these sound strategies in response to each species’ needs, creating a fascinating variety of acoustic mechanisms.

Conclusion

Noisemaking animals illustrate the diversity of natural ways to produce sound, without vocalization or breath. Among them, the rattlesnake stands out as a unique case, able to make noise with a dead structure that functions like a built-in percussion instrument. These mechanisms inspire bioacoustics researchers and remind us just how many ingenious solutions nature has engineered. Do you know other animals that produce sound in surprising ways?