Thursday, February 25, 2016

Peace on the beach

Breeding season is winding down, and the beach is much calmer. Dominant males are still being challenged by other males, but the level of energy is lower. They care, but not as much. Everyone is tired.

Weaner pups are molting their birth black coats. It's more like shedding than the actual skin peeling off that comes later in life.
Males mate as they can with females before they leave on the next stage of their migration.
We've had some high tides and big waves, but the weaners are able to navigate the beach away from high water. Soon the adults will be gone and they will have the beach to themselves.

Wednesday, February 3, 2016

Pups at high tide

Plenty of pups squirm on the beach in January, under the watchful eyes of their mothers. The bulls are less concerned, with their attention focused on mating. This year’s high tides and storms have added to the chaos.
Elephant seal pups can’t swim when they are born. That inability must be a holdover from their evolutionary past, when their ancestors were land mammals. As helpless pups, they are at risk of drowning as waves inundate the beach.

At Piedras Blancas this year, there’s almost no beach above high tide line at the north end of the boardwalk. Seals have crowded up next to the fence to stay above the water. Visitors are thrilled to get such a close look. But bulls battling each other and mothers shoving each other for space can separate mothers and pups, and make it difficult for them to reconnect. One docent counted 21 pups in a group that included only 14 possible mothers last week.
In the limited space left to mothers and pups, they crowded together to stay out of the waves. Look for mothers surrounded by three or four pups. Elephant seals give birth only to a single pup. Twins are unknown. Mothers don’t eat for that month while they are nursing the pup. They create milk by metabolizing their blubber. Each seal is plump enough to feed one pup, but not more. Any extra drains her resources further. 

Losing track of each other is serious, the single most common cause of pup death. Some mothers will nurse other pups, but other chase them away. Inexperienced mothers may learn from mothering other pups, but the milk they drink may deprive her own pup of the food he needs to grow. Some mothers are willing to foster a pup for a few days. Mothers whose pups die may adopt a stray, or even attempt to steal a pup from another mother.

Last week, one mother searched for her pup as the tide receded. Mothers and pups identify each other by sound and scent. She sniffed around, and barked occasionally. Pups around her slept on, but she likely reconnected with her little one before the tide returned. About 95 percent of the pups at Piedras Blancas survive to weaning.

The south end of the beach has more dry land for pups, so there’s less confusion there. Watch for the dominant bulls, beachmasters, to defend their harems. That big seal with a long nose may appear to be asleep, but he knows is some younger interloper tries to approach a female. He’ll warn the intruder off with a look and a bellow. If that’s doesn’t work, he’ll rise up and wave his nose. He’ll charge and attack the younger bull, who may escape or turn to fight.

Read the column in The Cambrian.