Bulls communicate

June is a month of transition, when seals of a wide range of ages mix on the beach. Adult bulls are starting to arrive to join the juvenile seals and adult females that have dominated the beach since April. The bulls, fat from feeding in the north, now take over the beach for the summer.

Molting is the annual peel-off of their hair and top layer of skin. It makes them look ratty, but it’s normal. The old hair is brown and tattered. The new skin, with newly emerging hair, is pearly gray.

Males are returning, with some of their hefty blubber restored after the 100 days they spent without food during the breeding season. Males feed along the coast of Alaska. They swim north from Piedras Blancas, covering 60 to 75 miles a day, after the winter breeding season is over. They mostly forage for bottom-dwelling prey along the continental slope of Alaska. They return swimming across the ocean, directly to the California coast.

Adult bulls are among the largest seals, at up to 5,000 pounds. They are surely dramatic, showing off their prominent noses and pink chest shields. Their guttural bellows echo against the bluffs.

New research on what their bellowing means shows that their calls have changed since the 1960s. Pioneering elephant seal researcher Burney Le Boeuf found the seals at different locations bellowed at different pulse rates. In effect, they were communicating in different dialects. That was the first time dialects had been identified in non-human mammal communication. When UCSC researcher Carolyn Casey re-analyzed Le Boeuf’s recordings and compared them to new recordings, she found the dialects had disappeared, but more individual variations had developed.

Geographical dialect may have disappeared as the population expanded and seals mixed more among beach sites. But their calls got more complex. Those individualized vocalizations help the seals know who is who.

Each individual male has his own unique vocal signature. Each bull knows his adversaries as individuals. They recognize each other by their calls, and remember who won the battle the last time. That simplifies seal life, in which dominance is important: No need to fight again. They’ve settled who won.

Bulls can keep track of 25 to 30 other bulls that way.

Without these new signatures, “it would be really difficult to distinguish everyone,” Casey said in an interview with The Atlantic magazine.

No need to fight during the summer molting months anyway. As important as it is for bulls to reign as dominant, to breed with as many females as possible, conserving energy is important, too. During the breeding season, a bull may go as long as 100 days without food. The bulls on the beach now are saving the blubber they’ve regained since the breeding season. They’ll rest on the beach for a few weeks, then return to the ocean to forage and bulk up even more, for the breeding season that begins in December.

Look for big, resting bulls on the beach. That nose, (technically, proboscis), and the chest shield, grow throughout a male seal’s maturity, starting around age five, so they are rough indicators of his age. Bulls can live to be 13 or 14. Females can live into their 20s.

Ask a Friends of the Elephant Seal docent, a guide in a blue jacket to touch some of the shed skin. They carry samples to share with the public. Most enjoy handling it, but some prefer only a cautious touch.