Last updated: May 7, 2020
Article
Elephant Seal Monitoring Season Summary: Winter 2018–2019
Season Overview
- Elephant seal population numbers were similar to last year, showing a minimal increase.
- The government shutdown reduced population and tag re-sight data collected this year.
- Winter storms caused some pup mortality. Approximately 900 pups survived to weaning, compared to around 1,000 pups last year.
- The seal take-over at the Ken Patrick Visitor Center garnered headlines across the globe.
NPS / S. Codde, NMFS Permit No. 21425
NPS / M. Cox, NMFS Permit No. 21425
Spotlight On Seals
The big news of the season was the formation of a large harem on the beach directly in front the Ken Patrick Visitor Center. While the recent trend has seen the movement of breeding seals down the length of Drakes Beach between the overlook and the visitor center, we have never had this much activity in front of the parking lot. Last year we had no pups born in this area, and in 2017 we had two pups born there. This expansion coincided with the government shutdown. A lack of people on the beach during this time, may have provided a more desirable pupping environment for females, and storm activity probably moved seals out of less protected ocean facing beaches. Dozens of national and international news outlets covered this phenomenon! Elephant seals, before their dramatic depletion due to hunting, did not haul out on mainland beaches like Drakes, because large predators like grizzly bears were still present in the area.
NPS / NMFS Permit No. 21425
NPS / Sarah Allen
Research Realized
Despite a 35 day shutdown and not so cooperative weather, park researchers were able to conduct weekly surveys, and document seal numbers in the park this year. In addition to surveys, flipper tagging of seals was conducted. This year researchers decided to attempt tagging of adult females at the visitor center harem, in hopes of determining if the same seals will return to the site in the future. In addition, weaned pups were tagged at all accessible beaches. In total, 6 adult females and 485 weaned pups were tagged! About 50% percent of weaned pups in the park were tagged this year. As seals continue to move into areas more accessible to humans our tagging percentage may increase.
NPS / Sarah Allen
F. O’Kelly, NMFS Permit No. 21425
By The Numbers
Elephant Seal Seasonal Peak Numbers Mostly Rising
Total Elephant Seal Counts, Winter 2018-2019
Female Elephant Seal Counts, Winter 2018-2019
Elephant Seal Pup Counts, Winter 2018-2019
Weaned Elephant Seal Counts, Winter 2018-2019
Weelky Updates Recap
News This Week
- We are back in action, and resuming bi-weekly elephant seal surveys when possible!
- Numbers are potentially at peak level, but we will have to wait for next week’s counts to determine the peak.
- The entirety of Drakes Beach is closed until further notice.
Our Point Reyes elephant seals are no longer just local heroes, they have been making headlines all over the country for their spectacular (possibly shutdown inspired) take-over of Drakes Beach at Ken Patrick Visitor Center. As of January 31 there were 53 cows and 52 pups! Last year no pups were born on this section of beach, and in 2017 only three pups were born here. The road to Drakes Beach will be closed on weekdays, and open 9-5 on weekends, with no beach access. It is important to remember that human disturbance to the seals can interrupt nursing, and could even lead to cow and pup separation.
FAQ
How much do they weigh? Northern elephant seal adult males can weigh up to 5000 lbs. and adult females up to 1500 lbs.
For how long do the pups nurse? Pups nurse for approximately 28 days, at which point mom will mate and leave for the open ocean.
How many pups are born to a cow? Only one pup per female, although twin births have been documented in Southern elephant seals.
How long do they live? Typically 10-19 years. Males tend to have a shorter lifespan than females, because of the enormous energy expenditure required to fight and mate.
What do they eat? They eat deep-water creatures such as fish, squid, and small sharks. Recent research has uncovered new information on female’s feeding habits (stay tuned!).
Why do they make so much noise? Female to pup vocalization are an important bonding tool and help mom find her pup if separation occurs. Adult seals (male and female) use much different vocalizations to display aggression. In females, aggression plays an important role in keeping her pup safe from other seals, and males use aggressive vocal displays to establish dominance in lieu of a physical altercation.
News This Week
- Peak elephant seal numbers were counted last week, with a total of 2,444 seals counted in the park!
- Storm event and high tides meant increased pup mortality
- Drakes beach, parking lot, and access road remains closed. On weekends from 9 am - 5 pm the road will open and visitors can access the parking lot and visitor center only.
Have You Heard?
Elephant seals don’t have external ears like humans, but that doesn’t mean that hearing doesn’t play an important role in their survival. Their ear is adapted for an underwater life, and their hearing is better under the waves, but hearing is an important tool on land as well. Female and pup pairs need hearing to recognize the distinct call of their mom or pup, helping them stay in close contact in a crowded harem. Males use hearing on land to recognize aggressive vocalizations of other males. When observing elephant seals it is important to remember to keep the human vocalizations to a minimum and at a low volume so as not to disturb the breeding activity.
What’s in a Name?
What is the origin story of the scientific name of the northern elephant seal, Mirounga angustirostris? Mirounga is derived from the Australian Aboriginal word for elephant seal, miouroung. While angustirostris is derived from the latin angustus, meaning narrow, and rostrum, meaning beak or snout. It seems that when scientist T. Gill proposed the name he had only seen and examined a female seal’s skull, apparently ignorant of the not so narrow proboscis of the male!
News This Week
- Total elephant seal numbers continue to decline as females leave the beaches.
- Mating and aggressive male interactions are ramping up.
- Researchers begin tagging seals.
- Drakes beach, parking lot, and access road remains closed. On weekends from 9 am - 5 pm the road will open, and visitors can access the parking lot and visitor center only.
This year researchers at Point Reyes will try to tag as many weaned pups as possible at Drakes, Chimney Rock, and South Beach, as well as adult females at the harem in front of the visitor center. Tagging is an important tool in tracking the movement and life history of individual seals, and is especially helpful at Point Reyes with all the movement we have seen in the past few years. The tags are meant for tagging the ears of cattle, but we apply the tag in the inter-digital webbing of the seal’s rear flipper. The tagging causes some discomfort to the animal, probably a similar experience to a human getting an ear pierced, but they recover quickly. Many seals have been observed falling right back to sleep post tagging! At the Año Nuevo colony, researchers from the University of California Santa Cruz apply scientific instruments to seals using a special glue. These instruments can record the animal’s movements such as dive depth and duration, feeding strategies, and general ocean conditions. One of their animals, an adult female, was spotted at the Point Reyes Headlands colony this week! The Año researchers hope to retrieve the tag from the hard to access beach, weather permitting. If you spot a seal with scientific instruments please contact park staff.
Role Call
With the peak of breeding activity upon us, there will be a lot of movement, fighting and mating taking place on Point Reyes beaches. Many males will start to congregate around groups of breeding females, and the alpha male will be busy fending them off. The alpha male can usually be spotted in the center of the harem, although he will frequently change position to mate and chase off other males. Alphas typically are very large, with an impressive proboscis and chest shield. Some harems, especially very large ones, will also have a beta male. The beta is usually closer to the perimeter of the bulk of females, and the alpha will allow the beta to be part of the harem and will even allow him to mate. Having a beta to help defend a large harem can actually be beneficial to the alpha, allowing him to conserve energy needed for mating. As more females come into estrus, more males will approach the harems and try their luck at mating. These peripheral males can successfully mate while the alpha is distracted or sleeping, or when females attempt to depart the beach after weaning their pup. A male who successfully mates even just once has beaten incredible odds. Approximately 5% of male seals survive to breeding age (7-8 years), and less than 1% of males successfully mate!
A Time to Mate
As mating activity increases it is common to see female elephant seals vigorously protesting when a male attempts to mate. Protesting mating, such as vocalizations and swinging the rear end, are normal behaviors for female seals. Female seals are in estrus for about three days at the end of the nursing period. Females will be much more receptive to mating near the end of their estrus period, and also typically more receptive to an alpha male over an interloper. Researchers believe that when a female selects a harem she is not selecting a particular mate, but looking for safety in numbers with her fellow female seals. However, since alphas have the health and stamina to beat the odds and make it to alpha status, the genes he is passing on are probably of superior quality.
News This Week
- Number of breeding female elephant seals dramatically decreased this week.
- Weaned pups begin to congregate in “weaner pods.”
- Researchers continue tagging seals.
- Drakes Beach, parking lot, and access road remains closed. On weekends, from 9 am – 5 pm, the road will be open and visitors can access the parking lot and visitor center only.
Who You Callin’ A Slug?
Elephant seals are adapted for an aquatic life, with limbs evolved into flippers. The hind flippers are not used when moving on land, while the fore-flippers are used to support and stabilize the body. Forward propulsion on land is created by spinal undulations, the more frequent the undulations the faster the speed. It is easy to assume that the mostly sedentary seals aren’t a threat to people, but they are faster on land then they look. When pursuing a female, evading a more dominant seal, or looking to engage in a fight, male seals can have bursts of speed up to 5.7 mph. This is faster than most humans walk, so if you aren’t paying attention and your back is to an animal they can easily overtake you. Always keep your distance, and never put yourself between two seals, especially when mating activity is frequent.
Cruise Control
Technology has done amazing things for elephant seal research, and one of those is an increasing knowledge of their behavior at sea. It is now known that when at sea, elephant seals spend about 90% of their time underwater, surfacing for only about 2 minutes between dives. They travel about 60-75 miles per day at about 2-3 mph. Keep in mind most of their swimming involves diving, and there is variation in dive behavior between males and females. Their top speed is about 10-15 mph. In comparison, a California sea lion can swim up to 25 mph and a great white shark up to 30 mph!
Delicious Fish
The adult female seals of Point Reyes are leaving for the open ocean, and will finally get to eat after nursing for about one month. Until recently, scientists had believed that the primary diet of northern elephant seals is squid. However, new research on satellite tagged females shows differing results. Previous studies showing squid as the primary prey have analyzed stomach contents of seals, the hard beaks of squid were more likely to survive in the stomach, thus the determination of squid preference. By sampling species in areas of known migration, and analyzing the fat of individual seals, these scientists were able to determine that female elephant seals are primarily feeding on meso and bathypelagic fishes. Examples of these intermediate and deep-water fishes are: lantern fish, barracudina, viperfish, and deep-sea smelts. While slow moving, “sit and wait” non-migratory squid are easier prey (and constitute about 1/3 of a seals diet), the fishes are much more energy rich and appear to be the preferred meal for female northern elephant seals. These fishy results also align with previous dietary studies of southern elephant seals!
News This Week
- Only 145 adult female elephant seals are left on Point Reyes beaches, down from the seasonal peak of 1,276.
- Inclement weather limited researchers tagging and survey time in the field this week.
- Drakes Beach, parking lot, and access road remains closed. On weekends, from 9 am – 5 pm, the road will be open and visitors can access the parking lot and visitor center only.
On February 11, Point Reyes researchers spotted an adult female seal with scientific instruments on her head and back. These instruments were deployed from Año Nuevo Reserve by researchers from UC Santa Cruz. The team at UCSC had to wait for favorable conditions to retrieve their tag, and that’s what they got this past Sunday, February 24. Upon arrival to Point Reyes they located their target seal using radio telemetry, and with that good news they were ready to launch. With minimal swell and low wind the researchers set off by boat to one of the colonies on the headlands. After landing they quickly located their target and were able to isolate her and retrieve their equipment. This seal was carrying a valuable Fluorometer CTD Tag. Not only does the tag record the seal’s use of their environment such as distance traveled and dive depth, but also oceanic conditions such as temperature, salinity, and chlorophyll concentration. Since elephant seals spend minimal time at the surface, where data can be transmitted via satellite, the tag itself needs to be recovered in order to collect all the data recorded. Check out https://anonuevoreserve.ucsc.edu/ to follow their research!
Chimney Rock Rocks!
Drakes Beach and the Ken Patrick Visitor Center are getting all of the attention this breeding season, but keep in mind we have thriving harems in other locations as well. In the rocky pocket beaches between the historic life boat station and Chimney Rock, we had two large harems this year with a combined total of 268 breeding females at peak. The rocky intertidal areas of these beaches protect the seals from large waves and tidal surges, and they are also an excellent place for weaned pups to learn to swim away from rough seas and ocean predators. Similar to Drakes Beach, this area is closed to the public during elephant seal breeding season.
Fatter Up!
Point Reyes beaches are filling up with hundreds of fat and healthy weaned pups. When pups are born they weigh about 75 pounds and by weaning time have inflated to about 300 pounds! This incredible weight gain, about 10 pounds a day during nursing, can be attributed to the rich milk of the elephant seal mother. When nursing begins the fat content of the milk is about 15% (human milk is 11% fat), and gradually increases to about 55%, plateauing after 21 days. This physiological system seems to play a role in water conservation. Fasting mothers are in-taking no water during nursing. As the pup develops water conservation strategies such as breath holding and increased insulation, the water content of the milk is reduced as fat content increases, helping to save some water for mom AND fatten up the pup!
News This Week
- Less than 100 breeding female elephant seals remain in the park.
- Weaned pups continue to congregate.
- Breeding males still present, hoping for their last chance to mate.
- Drakes Beach, parking lot, and access road remains closed. On weekends, from 9 am – 5 pm, the road will be open and visitors can access the parking lot and visitor center only.
South Beach
One of Point Reyes’ lesser known colonies is located on the far southern tip of South Beach. This colony has not seen the dramatic decrease in numbers that we have seen at the headlands, or the huge increase we have seen on Drakes Beach. Numbers have remained steady, and this year we recorded 57 females and 51 pups at peak. The deep beaches, with abundant sand, are welcoming to breeding seals. However, this beach faces the open ocean and can be hit by massive waves. South Beach is not ideal for weaners learning to swim, there aren’t any tide pools and the seas are often rough. Thanks to this year’s heavy rainfall big pools have formed on the beach, allowing the weaners a safe place to paddle. This area of the beach is closed during the breeding season, with the closure starting about three miles south of the South Beach parking lot.
Earlier in the season a researcher spotted a radio tagged yearling (a seal born last year) on Drakes Beach. The seal had a dye mark and green flipper tags, which means it came from Año Nuevo. Researchers at Año Nuevo were quickly notified and were able to rush to Point Reyes that day. They successfully located and retrieved the equipment, and while they were there found another one of their yearlings with a radio tag! The preliminary data collected from these tags show that these young seals are capable of deep dives as soon as they leave for the open ocean. One of the seals reached a depth of almost 790 feet after only three days at sea, and after two months the seals were diving as deep as 2,100 feet! The Año Nuevo researchers attached radio tags to 24 weaned pups, and the two tags found in Point Reyes are the only recoveries so far. Yearling seals return to land in March and April to molt their first layer of skin and fur and the tag will then fall off. The Año Nuevo researchers are hopeful they will be able to locate more of their tagged seals in the coming weeks.
News This Week
- Only 17 breeding female elephant seals remain in the park.
- Weaned pups continue to congregate, and begin to move into water for swimming practice.
- Very few breeding males still present.
- Drakes Beach, parking lot, and access road remains closed. On weekends, from 9 am – 5 pm, the road will be open and visitors can access the parking lot and visitor center only.
As adult females depart for their post breeding foraging trip, this provides an opportunity for subordinate males to mate. Females typically depart at night or during high tide, which makes it easier to sneak away. However, if she is not stealthy she may attract a group of males. Often the alpha will follow her into the water, while fending off other males. If the alpha is distracted during a female departure, then peripheral males may get the opportunity to mate with the isolated female.
Vibrant Vibrissae
While the elephant seal’s excellent under water vision certainly plays a role in prey capture in deep water, other tools must be put to use in these low-light conditions. Elephant seals have 3 sets of vibrissae, or whiskers: mystacial (on either side of the nostrils), rhinal (above the nostrils on top of nose), and supra-orbital (above each eye). The vibrissae are innervated, supplied with many nerves, and are used to detect movement in the water, which in turn helps them locate prey. The seals have fine motor control over their vibrissae, and are able to protract them when stimulated. Each vibrissae is beaded or grooved, which is a characteristic of almost all phocid (true seal) species. The beading increases sensitivity to vibration in the water produced by prey movement.
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