Point Reyes National SeashorePage 197 of 259
Elephant seals’ catastrophic molt: why it is not as bad as it sounds
“Catastrophic” sounds bad, but for an elephant seal the catastrophic molt is a regular part of life. It simply means that fur and the top layer of skin come off in large patches, so the seals look ragged for a while. This National Park Service article is by Ellen Greenblatt, a Point Reyes National Seashore volunteer, and is the final chapter of the series Elephant Seal Tales.
Why seals must molt on land
At sea, a seal’s body sends blood away from its extremities and toward the core to keep vital organs warm. Molting needs blood flow to the skin, so the seals must be on land for the whole process, or they would get too cold. As always on land, they fast.
After the breeding season
By early March most females have finished giving birth and nursing and have left the beaches. The males, with no one left to fight over or mate with, have little to do, and the only ones left are yearlings, subadults and bulls that did not mate.
Weanlings
Females nurse pups for about 28 days. The weaned pups, or weanlings, then live off the fat they built up and, in early March, mostly have not learned to swim or hunt. Weanlings normally top out at about 300 pounds, but “superweanlings” that nursed from two cows can weigh as much as 600 pounds. Point Reyes marine biologist Sarah Codde says they are rare there.
For two to three months the weanlings stay on the beach, practicing swimming and diving in shallow water and sleeping in packed pods. Pinniped scientist Burney Le Boeuf notes that once pups learn to dive, even on a first trip to sea at about 3 and a half months old, their dives are deep and long compared with other diving mammals. By age 2 they dive as deeply as adults. After leaving the pods, they become mostly solitary deep-water hunters, gathering with other seals only to molt, mate and give birth.
Tagging
Park professionals tag pups while they are still on land, which can be dangerous. Volunteers join the tagging only after extensive training and long commitment, but they help gather data to identify tagged seals and alert staff.
Seals tagged at Point Reyes get pink tags on a hind flipper. Other sites use other colors: green for Año Nuevo, white for San Simeon, and orange for seals released by marine mammal rescue centers. Color coding helps researchers follow migration even though seals tend to return to the same beach each year.
A life of extremes
| Stage | What happens |
|---|---|
| Fasting on land | Males neither eat nor drink during battles and mating. Females neither eat nor drink during birth, nursing and mating. |
| Feeding at sea | After mating and weaning, females hunt deep waters for a couple of months. Males go off in a different direction for a few months. |
| Fasting to molt | Females return to the same beaches and fast for about a month while they shed and grow a new coat. Males return later. |
| Feeding again | Once comfortable in their new coat, they leave their pod and head to sea alone until next winter’s breeding season. |
A docent’s verdict is that watching a molt is like watching paint dry. The article also credits interns and Winter Wildlife Docents, volunteers who help visitors see and understand the seals, and the author has applied to join them.
Please do not disturb seals. Observe all elephant seal protection closures and stay at least 25 feet from seals outside them.
Sources
- National Park Service, Point Reyes National Seashore, https://www.nps.gov/articles/000/elephant-seals-march-catastrophic-molt.htm; rewritten in hubnx's own words.