Why Do Sea Lions Bark? Sea Lion Sounds Explained

Male sea lions bark to defend territory

Most of the barking you hear comes from adult males. During the breeding season, from about May to August, large males set up territories on beaches and rocky shores where females gather to give birth and mate. A male has to keep other males out of his patch for weeks, and fighting is risky and exhausting, so most of the work is done with sound and display.

Territorial males are the loudest and most persistent callers. At the peak of the breeding season they bark almost nonstop, and they bark faster when excited, for example when a rival approaches. Barks are combined with head-shaking, staring and short bluff lunges along territory borders. These ritual displays usually settle disputes without serious injury.

Males that hold territories tend to have deeper barks than younger males without territories, and a deep, steady bark may help advertise size and stamina to rivals and to females. Males also bark during courtship. When startled, for example by a person, a male may give a prolonged, hoarse grunt instead.

Mothers and pups call to find each other

The other key sounds in a colony come from mothers and pups. A California sea lion mother leaves her pup on shore for several days at a time while she feeds at sea. When she returns, she must find one pup among hundreds.

She gives a loud pup-attraction call, and her pup answers with its own call. Each mother and pup has a distinctive voice, and they learn to recognize each other’s calls early in the pup’s life. Once she finds the pup that answers, she sniffs it as a final check, because each pup also has its own scent. Pups also bleat and bark when they play or are distressed.

Other sea lion sounds

California sea lions make a surprising range of noises:

• Female barks: shorter and higher-pitched than male barks, mostly used in squabbles.
• Squeals, belches and growls: aggressive or defensive sounds, especially between females.
• Pup bleats: high, lamb-like calls from young pups.
• Grunts: given by startled males and by groups of non-breeding males.
• Underwater sounds: barks, whinny-like calls, buzzes and trains of clicks.

In the 1960s, researchers studying captive sea lions asked whether those underwater clicks might be used for echolocation, the sonar system that dolphins use to find prey. Later work found no good evidence that sea lions echolocate. They find food with their eyes, which work well in dim water, and with their long, sensitive whiskers, which can detect vibrations.

Why are sea lion colonies so noisy?

A sea lion colony is crowded. Hundreds or thousands of animals may pack onto one beach or dock, and every newcomer has to push in, argue over space and settle down again. Males guard territories, females quarrel over resting spots, and mothers call for pups, so the noise rarely stops.

Non-breeding groups are noisy too. The mostly male colony on the floating docks at Pier 39 in San Francisco barks loudly while the animals jostle for space, and soon after they arrived in large numbers in 1990, the noise and smell brought complaints from boat owners. Today the barking is part of the attraction, as explained in Why are there sea lions at Pier 39? For some of the noisiest creatures on Earth, see our list of the loudest animals.

Do seals bark like sea lions?

True seals, also called earless seals, are generally much quieter on land than sea lions. Harbor seals mostly snort, grunt and growl when ashore, and gray seals are known for their eerie moans. Many true seals save their most complex sounds for underwater. Male harbor seals make low underwater roars during the breeding season, and bearded and Weddell seals produce long trills and whistles beneath the ice.

There are loud exceptions. Bull northern elephant seals produce deep, rhythmic, drum-like threat calls through their huge noses, and rival males learn to recognize each other’s voices.

Sea lion species also differ. The California sea lion’s dog-like bark is the classic sound, while the much larger Steller sea lion, found farther north, gives deep roars and growls. The shaggy, mane-like neck fur of adult males in some species, along with their deep roars, is often given as the reason these animals were called “sea lions” in the first place.

Does a barking sea lion mean trouble?

Not usually. Most barking is aimed at other sea lions, not at people. But a sea lion that turns toward you and barks, swings its head from side to side, opens its mouth or lunges is warning you that you are too close. Large males can weigh several hundred kilograms and can bite, so take the warning seriously and back away slowly.

In the United States, sea lions are protected by the Marine Mammal Protection Act, and disturbing them is illegal. NOAA recommends watching seals and sea lions from at least 50 yards (46 m) away and never feeding them. More on staying safe is in Are sea lions dangerous?