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The elephant seal season at Point Reyes National Seashore in winter 2020–2021 ended with the highest count of weaned pups on record. Overall numbers were slightly higher than in winter 2020, and the colony on Drakes Beach kept growing and moving up the beach toward the Ken Patrick Visitor Center. A big storm from the south in January separated some pups and caused some deaths, but mortality was low overall. This is the park’s season summary, with its weekly notes folded in.
A cove full of seals near the peak of the season; the highest number of seals in the park is usually counted in late January. NPS / Marjorie Cox.
A harem at the visitor center
In 2019 a storm pushed nursing females and pups onto the beach in front of the Ken Patrick Visitor Center, and Drakes Beach was closed completely. In the next two years park staff used deterrence to keep females from pupping there. In late January 2021, another storm sent 12 females onto the beach overnight, and one gave birth. Since pups were present, staff stopped the deterrence, and a harem of about 20 females formed. Drakes Beach closed in full again, but visitors had a view of nursing mothers, pups and the dominant bull from the sidewalk. Fourteen pups were born in that harem and 13 survived to weaning.
Mothers and pups on Drakes Beach. NPS / Marjorie Cox.
The numbers
The park’s five-year comparison of peak counts, from direct ground counts, shows a growth trend. The peak cow count of the year before was slightly below 2019’s, possibly because of poor visibility during that year’s surveys. Counts at the three breeding colonies were above the 2005–2017 average from mid to late January. The first pup of the season was counted on December 21 and the first weaned pup on January 19.
Seasonal peaks of cows, pups and total seals, 2017–2021, from ground counts. NPS.
| Place | Count |
|---|---|
| Elephant Seal Overlook, peak of breeding | 258 females |
| Elephant Seal Overlook, high count of pups | 227 |
| Drakes Beach, peak of breeding | 442 females |
Drakes Beach now has the highest numbers of any site in the park. Few pups were born there for three decades, and harems did not spread farther down the beach until 2016. The Overlook colony began in 1995, when a storm pushed a harem of 13 females into Drakes Bay; 11 pups survived. By 2010 over 300 females were seen there at peak breeding.
Seal notes from the season
| Topic | What the park wrote |
|---|---|
| Size | Adult males weigh up to 5,000 lbs, adult females up to 1,300 lbs and newborn pups about 70 lbs |
| Diving | They spend about 90 percent of their time at sea underwater; an average dive is 300–800 meters, and the deepest recorded was over 1,700 meters |
| Napping | Seals that look dead may just be in apnea, holding their breath, which saves water and energy while fasting; adults average breath holds of 6–8 minutes and can hold them up to 25 minutes on land. Turkey vultures are the surest sign a seal has died |
| Milk | Pups weigh about 75 lbs at birth and about 300 lbs at weaning, gaining about 8.5 lbs a day. Milk fat rises from about 15 percent to about 55 percent, against about 5 percent in human milk |
| “Runny noses” | The white fluid is pulmonary surfactant, which lets lungs re-expand after the pressure of deep dives collapses them |
| Tongues | Elephant seals have forked tongues and catch food by suction, not teeth; the cause of split tongues needs more research |
| Predators | White sharks feed on them. Researchers saw three subadult males with fresh, probably survivable bites, and a tagged 16-year-old pregnant female with a large healed shark wound, seen five times since 2013 pregnant or with a pup |
An adult female, probably returning to molt, among weaned pups. NPS / Marjorie Cox.
Pups growing up
Pups are born in a fuzzy black coat and after about four weeks of nursing are fat enough to wean while still black. They start molting several days later, and fully molted pups in silvery gray were being seen by late February. Weaned pups tend to be pushed out of the harem by nursing females and gather in pods, where they learn swimming and diving from each other. Pups usually take a couple of weeks to try the water, but late weaners go in sooner, apparently following the older pups. Park researchers tag weaned pups in the hind-flipper webbing with tags made for sheep, so they can be identified for years; over 300 pups were tagged by late February, and one alpha bull below the Overlook still wore the tag he got as a pup, at 13 years old. Weaned pups also play-fight, which prepares them for adult fights.
Hazards
Headland beaches, where in 1981 the first pup was born after the species was hunted out of the park, are small pocket coves safe from land predators. Erosion and bigger storms linked to climate change have shrunk them, and storms can wash seals out and separate pups from mothers. Seals under the cliffs of Drakes Bay risk rockfalls and landslides. In March the park, with The Marine Mammal Center, freed a nursing female from a plastic strap around her neck.
The yearly cycle
Seals are in the park all year. Adults come ashore twice, to breed and then to molt, and juveniles come for their own haul-out and to molt. Female molting peaks from April, so a large female seen late in the season is probably returning to molt, not pregnant.
Sources
- National Park Service, Point Reyes National Seashore, Elephant Seal Monitoring Season Summary: Winter 2020-2021; weekly closure notices and the data disclaimer are left out; rewritten in hubnx’s own words.
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About this page
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
In these publicationsPoint Reyes National Seashore
