Elephant Seals Take Over a Visitor Center Beach: Point Reyes' 2018–2019 Season

During a 35-day federal government shutdown in winter 2019, elephant seals formed a big breeding colony on the beach directly in front of the Ken Patrick Visitor Center at Point Reyes National Seashore, and news outlets around the world covered it. As of January 31 the colony held 53 cows and 52 pups. The year before, no pups had been born in that area. Park staff suggested that fewer people on the beach may have made it a more appealing place for pupping and that storms probably pushed seals out of less protected beaches facing the ocean. This page retells the park's season summary for winter 2018–2019, which also records weekly updates, the season's numbers and a good deal of seal natural history.

The visitor center harem at the peak of the breeding season (NPS photo by S. Codde; NMFS Permit No. 21425).

The season at a glance

• Population numbers were similar to the previous year, with a minimal increase.
• The shutdown reduced the population and tag re-sight data collected.
• Winter storms and high tides caused some pup deaths. About 900 pups survived to weaning, against around 1,000 the year before.
• The peak count, taken in the first week of February, was 2,444 seals in the park, including 1,276 adult females. By March 1 only 145 females were left, and by March 15 only 17.

Before hunting nearly wiped them out, elephant seals did not haul out on mainland beaches like Drakes Beach, because large predators such as grizzly bears were present.

Where the seals were

Research

Despite the shutdown and bad weather, researchers kept up weekly surveys. They tagged 6 adult females at the visitor center harem, to see whether the same seals return, and 485 weaned pups, about half of the weaned pups in the park. The tags are made for cattle ears and are placed in the webbing of the hind flipper, which causes brief discomfort, like having an ear pierced, and many seals fell back to sleep. Researchers from the University of California, Santa Cruz, who study seals at Año Nuevo, found one of their tagged females at the Point Reyes headlands and recovered a valuable instrument that records the seal's dives and travel as well as ocean temperature, salinity and chlorophyll. They also found two tagged yearlings, which showed that young seals can dive deep as soon as they go to sea: one reached almost 790 feet after three days and others went as deep as 2,100 feet after two months.

A researcher prepares a flipper tag for a sleeping adult female (NPS photo by Sarah Allen).

What the weekly updates taught

• Size. Adult males can weigh up to 5,000 pounds and females up to 1,500. Pups weigh about 75 pounds at birth and about 300 at weaning, gaining some 10 pounds a day on milk that goes from about 15% to 55% fat, which may also help the mother save water.
• Nursing. Pups nurse for approximately 28 days, then the mother mates and leaves for the open ocean. A female is in heat for about three days at the end.
• Males. Only about 5% of males survive to breeding age (7–8 years), and fewer than 1% mate successfully. The alpha male stays at the center of a harem and may tolerate a beta male on its edge, while peripheral males mate when the alpha is distracted or when females depart. On land, males can reach 5.7 mph in bursts, faster than most people walk.
• At sea. Seals spend about 90% of their time underwater, surfacing for only about 2 minutes between dives, and travel 60–75 miles a day at 2–3 mph. Squid, long assumed to be their main prey, make up about a third of a female's diet, while energy-rich deep-water fish such as lanternfish appear to be preferred, according to newer work on satellite-tagged females.
• Whiskers. Seals have three sets of sensitive whiskers that detect movement in the water, which helps them find prey in low light.

The park reminded visitors that disturbance can interrupt nursing and even separate a cow from her pup, so Drakes Beach was closed and the road to the visitor center open only on weekends.

Sources

• National Park Service, Elephant Seal Monitoring Season Summary: Winter 2018–2019, Point Reyes National Seashore; rewritten in hubnx's own words.