Climate Change and Point Reyes Elephant Seals: Storms, Heat and a Shrinking Beach

Elephant seal mothers keep their pups away from the water until they can swim. NPS / Marjorie Cox, NMFS Permit No. 21425

Every winter, northern elephant seals (Mirounga angustirostris) haul out on the beaches of Point Reyes National Seashore to give birth. A female mated at the end of the previous breeding season arrives in early January, bears a single pup, and spends the next few weeks nursing it and keeping it safe. Because young pups can't swim, a safe beach is everything — and climate change is changing which beaches are safe.

Storms: the Headlands versus Drakes Beach

A Point Reyes Headlands beach during a king tide, December 2020. NPS / Marjorie Cox, NMFS Permit No. 21425

Extreme storms at Point Reyes have become more common with climate change, and they're expected to become more frequent still. Sheltered bay beaches will feel them far less than ocean-facing ones.

NPS biologists have tracked the seals since the colony first appeared in the 1980s. In 2015, the Headlands and Drakes colonies were about the same size — nearly 300 adult seals each. Three years later, Drakes had record numbers, while the Headlands colony had crashed. Many factors may be involved, but climate pressures that make the Headlands less suitable are among them.

Peak-season counts of females and pups at Drakes Beach and the Point Reyes Headlands, 1999–2022. Image from the National Park Service's page

Heat: cooling off in the surf

Elephant seals overheat on warm days, and a warming climate is bringing more of them, even in the winter breeding season. Mothers normally stay out of the water until their pups are weaned — but on warm days, researchers have seen mothers bring pups to the water's edge so gentle waves wash over them both. At a calm beach like Drakes, that's safe; on an ocean-facing beach it would be dangerous.

A mother and pup cooling off in the gentle surf of Drakes Bay. NPS / NMFS Permit No. 21425

Rising seas: a beach with nowhere to go

Drakes Beach is narrow and backed by cliffs. As the sea rises, the beach will shrink with no room to retreat. Seas here could rise as much as six feet by 2100, putting much of Drakes Beach underwater and leaving room for few seals.

North Drakes Beach, below the Elephant Seal Overlook, nearly vanishes at a king tide — a preview of sea level rise. NPS / Marjorie Cox

North Drakes Beach at a normal-to-low tide. NPS / Sarah Allen

Biologists think the seals may move to nearby Limantour Beach, also on Drakes Bay, with calm water but backed by dunes rather than cliffs — more room, even as it narrows. But the move could ripple through Limantour's ecosystem: the federally threatened western snowy plover, for one, could lose nests to lumbering seals.

How to help

• Follow the elephant seal monitoring team's updates.
• Keep your distance and use the viewing areas.
• Practice Leave No Trace.
• Volunteer as a docent in the Winter Wildlife program.

Sources

Based on Claire Baker (science communication intern, Point Reyes National Seashore Association), "The Rippling Effects of Climate Change on Elephant Seal Habitat" (December 2022), National Park Service, with information from marine ecologist Sarah Codde; a work of the United States government in the public domain; rewritten in hubnx's own words.