Pinniped Monitoring

Two adult harbor seals and a pup on a beach
Harbor seals resting on a beach

© Trish Carney

Hauled-out on sandy safe havens, harbor and elephant seals are monitored in the San Francisco Bay Area Network by park biologists and a large group of dedicated volunteers. The coastlines of Point Reyes National Seashore and Golden Gate National Recreation Area provide excellent habitats for both seals and their prey.

By the late 1800s, northern elephant seals (Mirounga angustirostris) had been nearly hunted to extinction. Today, a growing number of elephant seals breed at three colonies at Point Reyes. Each year during the breeding season, the park monitors these seals to help understand population changes and management needs, and to develop research, interpretation, and enforcement strategies. Monitoring data has been collected at the park since 1980, providing valuable information on long-term trends.

Although elephant seals are only in the area for part of the year, harbor seals (Phoca vitulina richardii) remain in the parks year-round and can provide valuable insights into the condition of marine and coastal ecosystems. Golden Gate hosts a small population of a couple hundred harbor seals, while Point Reyes hosts the largest concentration of seals in the State of California, boasting an estimated 7,000 individuals. The harbor seals in the San Francisco Bay Area are part of a stable population, but they are not immune to diseases, changes in food supply, disturbance to haul-out sites by commercial and recreational use, and environmental changes such as rising sea levels. Harbor seals have been monitored at both parks during the breeding and molting seasons since 1995.

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[MUSIC PLAYING] I think it's fair to say that Point Reyes is like pinniped heaven. As you can see from the beaches out there it, is a magnet for elephant seals, for harbor seals. It's just a natural haven, a natural sanctuary for these animals to come and rest, and reproduce, and recharge.

Out of all the pinnipeds in Point Reyes, one of the most charismatic, also the one that draws the most visitors is the elephant seal, just because there's so much story to them and they're just so much more active. They really put on a show, basically, with all of the fighting, and the interactions, and the pups. There's just a lot more to see.

Elephant seals used to prehistorically be in California. So they were hunted almost to extinction. They're a great story of a species to recover with simple protection by places like national parks.

Right now, in Point Reyes is their breeding season, which is during the winter. And so a lot is going on at that time. Males show up first. They compete with each other to figure out who's going to be the alpha. Then the females show up. Within a few days, they give birth. They nurse their pups for about 28 days on average. Then they're going to wean their pup, and then they're going to leave. But while that's all going on, the males are still constantly fighting each other.

We study elephant seals and we monitor them. That means we study them year after year. And we put that data together so we can understand what's the trend of the population. Is it going up? Is it going down? Is it flat?

To do the surveys of elephant seals in Point Reyes, we have two strategies. The easiest way to count the seals is actually to be up above, so to be up on cliffs. And we're using a spotting scope. And that gives us a much wider, more on top view of the animals. And so we'll use spotting scopes or binoculars.

But sometimes we have areas where we just can't really get that kind of a viewpoint. And so we actually have to be on the beach with the animals. And we're really trying to do accurate counting. And we want to make sure we don't miss, and especially the pups that might be hiding behind the females.

Another part of our monitoring process is tagging the weaned pup. And a weaned pup is what the word sounds like, a pup that has been weaned, so the mom is no longer nursing it. And for now it's off on its own, away from the harem. And so we're going to go and try to apply a flipper tag. And we wait for that to happen because we don't want to interrupt that bonding process or the nursing process between the mom and her pup.

The best way to tag an elephant seal is to sneak up on one that's asleep and do a real quick punch into their flipper. Most of the time, they do react. It's just like if you were asleep and someone came up and pinched you. You would probably react.

So it wakes them up. They might squeal a little bit because of their surprise. But usually they calm down within a few seconds or a few minutes after it happens. Five, 10 minutes later, most the time they're back asleep.

Well, we went through that question. Why tag elephant seals? And we decided that we would tag them because it helps us to understand the exchange between the other colonies because we share our data with the other researchers at the other colonies in central California. And by doing so, we understand better the whole population of central California, which is the leading edge of growth for elephant seals.

Tags can tell you about survivorship. You know the age of the animal, you know the location where it was born. They can tell you a lot of things. Most of the tagged animals we see are from Point Reyes. That tells us that it's a more stable population and animals are coming back to Point Reyes to breed.

Elephant seals definitely need a safe place to come raise their pups. The pups can't really swim at birth for at least the few first weeks. So they need an area on a beach where they're not going to get washed out by waves. They need the safety of the sand, and they need the safety from people.

So we close the beaches to people because people are dangerous to elephant seals and elephant seals are dangerous to people. If people disturb elephant seals, that can cause them to displace pups and females and males. And if people get too close to females, they can attack them and bite them. So it's best for both to have these beaches protected.

As biologists, we do need to go into the colony where most people can't access. But we are trained to recognize for animal behavior. Also, we know how to act around them. So we know when to keep our distance and when we can maybe get a little bit closer. So we're trained really to make sure that we are not causing any disturbance that is not necessary.


Marine ecosystems are important, and it's important for us to understand them better because it's hard to study them. And so we may know a bit about the surface of the ocean, but not much about the deep ocean. And elephant seals are the bridge between the surface and the deep ocean because they dive so deep.

And when somebody goes to the beach, they just see the ocean's surface. They don't understand the depth of it. When you look at an elephant seal, and you think this animal's dove a mile under water, what is it seeing down there? How can it stay down there for an hour and a half?

So understanding the ecology of national parks is vital to what we do. It's vital to what I do as a park manager. When I'm making decisions about how we're going to manage the park, how we plan for the future, how we insure these animals are here for future generations to enjoy, how we protect people today, understanding what's going on the ground with the wildlife is absolutely critical. And that's when inventory and monitoring does for us.

The inventory and monitoring program is not a new concept. It evolved over 20 plus years in the Park Service. But we're the leaders of many agencies in implementing it. And the data that we're getting back is already being used to help us to be better stewards. It's a fantastic program, it's a model for the nation, and we do it with a little money and a lot of leverage with partners, and friends, and citizen scientists, and volunteers. Everybody's a steward.

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7 minutes, 1 second

Point Reyes National Seashore is "like pinniped heaven." Out of all of the pinniped species that use the park's coastline, elephant seals are the most charismatic. Discover how and why National Park Service scientists study the elephant seals at Point Reyes year after year.

Monitoring Documents

Source: Data Store Saved Search 1891. To search for additional information, visit the Data Store.

Source: Data Store Saved Search 1892. To search for additional information, visit the Data Store.

Source: Data Store Saved Search 1834. To search for additional information, visit the Data Store.

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    Last updated: August 7, 2018