Why do wolves howl?

Why do wolves howl? The short answer

Wolves howl to talk over long distances. Of all the sounds a wolf makes (barks, whines, growls, whimpers), the howl is the only one built to travel far.⁴⁵ Wolves use it for two big jobs: finding and gathering their own family, and telling other wolves that a territory is already taken.²⁶ As Yellowstone wolf biologist Doug Smith put it: "one howl is 'stay out,' and the other howl is 'where are you?'"⁶

And no, it has nothing to do with the Moon.²⁴

A family phone call: finding the pack

A wolf pack is a family, usually a mother and father and their offspring.³ Packs are often 5 to 10 wolves,³⁹ and a pack's home ground can cover anything from 80 to 3,000 square kilometres (31 to 1,200 square miles).⁹ Wolves travel a lot, so family members often end up far apart. A howl is how they find each other again.⁵

Wildlife biologists describe pack members howling back and forth to work out where everyone is, using long howls that gently rise and fall.⁷ Howling also works as a rally call: a "let's get together" before the pack sets off.²³

One special call is the lonesome howl. A wolf that's been separated from its pack gives a shortened call that rises in pitch. If the pack answers, the lost wolf switches to deep, even howls that help the family find it.²³ Separate a wolf from its pack, wrote wolf-howl expert Fred Harrington, "and very soon it will begin howling, and howling, and howling..."⁵

How far can a wolf howl be heard?

A howl is low and long, and sounds like that carry well through forest and across open tundra.⁵ (Curious how a sound gets from one place to another at all? See how sound travels.)

That's why the listening-wolf toy in chapter 2 switches between forest and open land: the same howl reaches much farther when nothing is in the way.

Every wolf has its own voice

Wolves can tell who is howling. Researchers found that wolves notice small differences in the overtones of each other's howls, which makes it possible to recognise one another from far away.¹ Scientists see it too: when howls are drawn as pictures of pitch over time (a spectrogram), each wolf's howl has its own shape.¹⁵

A howl also carries mood. A more excited wolf howls at a higher pitch, and a lower, rougher howl sounds more threatening, just like in many other mammals.¹⁵ Wolf pups have shorter, higher howls because they're small, and young pups will answer almost any howl they hear. By about six months old they get choosier about when to howl and to whom.⁵

By comparing thousands of recordings, one team of scientists sorted the howls of wolves, coyotes and their relatives into 21 different howl types.⁶

Do wolves howl because they miss each other?

Maybe, in a way. In a 2013 experiment with captive wolves, researchers took one wolf out of the group at a time and listened to who howled. Wolves howled more when the wolf leaving was one they had a close relationship with. The researchers also measured cortisol, a stress hormone, and found that the relationship predicted howling better than stress did.¹⁰⁸ So a howl isn't just an anxious reflex. It seems to depend on who's missing.

"This land is taken": howling and territory

A howl doesn't only reach the family. Any wolf within earshot can hear it, including wolves from neighbouring packs.⁵ So howling also works like a sign on a fence. Nearby packs often answer with a chorus of their own, and very quickly all the wolves know where everyone is.⁵⁷ That helps packs keep their distance and avoid bumping into each other by accident, which means less need to defend a territory face to face.⁵⁷

Wolves back up the message with scent. They mark their territory with urine and scat, and a wolf's nose is about 100 times more sensitive than ours.⁴

The chorus trick: why 2 wolves can sound like 20

When a whole pack howls together, it's called a chorus howl. Each wolf howls at its own pitch, and the voices slide up and down and overlap. Washington State's wolf biologists say you might pick out four or five wolves, but it gets extremely hard to count more than that, even for experts.⁷ Harrington points out that by the time three wolves have joined in, the first is ready to howl again, so you can't tell a new wolf from an old one.⁵

The US general Ulysses S. Grant once heard howling while riding in Texas and guessed there were about 20 wolves. When he got closer, there were two.¹³ Scientists think this effect may be useful: packs that sound bigger may be better at keeping their neighbours away.⁵

Do wolves really howl at the Moon?

No. Wildlife experts at the Smithsonian's National Zoo, the International Wolf Center and Washington's wildlife agency all call it a myth.²⁴⁷ Wolves can howl at any time of day, but we mostly hear them in the evening, when the wind dies down and the wolves are most active.⁴ Wolves and coyotes howl most from late evening to early morning.⁷ So when a wolf howls, the Moon is often simply up there too. Wolves also raise their heads when they howl, which in pictures makes them look as if they're singing at the sky.

Seasons play a part. In Yellowstone, researchers went through more than 11,000 howls recorded over 10 years and found that wolves howled about four times more in February than in May.¹ Howling peaks in the winter breeding season.³ Writer Barry Lopez suggested that's how the myth grew: long, cold, clear winter nights, sound carrying far, and a bright Moon over the snow.¹³

Why do dogs howl?

Dogs descend from a wolf ancestor, and they inherited much of their body language and many of their sounds from wolves.⁴¹¹ Many dogs howl at high, wailing sounds like sirens or some musical notes. The American Kennel Club suggests a dog may hear these as something like a howl, and simply join the chorus.¹¹ Dogs don't use howls in exactly the same way wolves do, though: they live very different lives, and they bark far more.¹¹ (Dogs don't see the world the way we do either. Here's how dogs see.) And a dog's tail talks too: why dogs wag their tails.

Where can you hear wolves howl?

Wild wolves live across North America, Europe and Asia, in forests, mountains, tundra, grasslands and even deserts.¹² One famous place is Yellowstone National Park, home to both a supervolcano and wolf packs. Wolves had been wiped out across most of the lower 48 US states in the early 1900s,¹² and in 1995 wolves from Canada were brought back to Yellowstone.⁹ Since then, researchers there have recorded and studied thousands of howls.¹⁶ Many zoos and wolf centres also have wolves you can hear. If you ever do hear wolves in the wild, enjoy it from a distance and give them space. Wolves are shy and usually keep away from people. They are one part of a web of wild life; see why biodiversity is important.

Common myths about wolf howls

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