Science Behind the Scenery: Northern Elephant Seals

Point Reyes National Seashore


[elephant seals barking and yelping]

[wind blowing across microphone]

[Sarah Allen] Everything about elephant seals is fairly remarkable. They're really big animals. So, males can get up to five thousand pounds, and a female is a thousand pounds. They're big in size. And this enables them to dive very deeply. They can dive over a mile deep. And, then, we know that from various satellite telemetry devices that have been attached to the seals. And that provides that information of how long they'd stay underwater—which can be up to almost two hours long—and how deep they dive. One of the devices imploded, the animal was diving so deep.

[elephant seals yelping and calling, which continues as Sarah resumes speaking]

[Sarah Allen] Elephant seals come in to breed one time per year, and that is in the winter months. They come in Nov...the males arrive first around in November. The females give birth starting in December, and that extends into March. The pups stay with the females for only 30 days. And then, the female weans the pup and leaves. So, the season for breeding extends from December through March.

At that time, the females will go to sea, and they'll stay at sea for several months. They'll migrate to the north and...and west towards the Hawaiian Islands. Male elephant seals, on the other hand, migrate far north into the Aleutian Islands.

In fact, some of the weaned elephant seals that we've tagged at Point Reyes headlands have gone remarkable distances. One weaned elephant showed up in Russia on Medny Island, which is part of the Komandorski Islands.

[pups belching, squealing, and barking]

[Sarah Allen] So, there's no pressure to prevent elephant seals from expanding into new areas. And new colonies are being formed. There have been colonies established in the Channel Islands. And then, Año Nuevo is probably the most well-known colony, because it is on the mainland and pub...the public can access this colony. That colony was formed in the early 1960s.

And then, the Point Reyes colony, which is really the northernmost colony, was established from 1981. And that was when the first female arrived and gave birth. And from that one birth, that humble birth, many have since been born there. And the population is growing exponentially. So, just last year, 2003, there were over 450 pups born at Point Reyes Headlands. So, we're monitoring this exponential growth of elephant seals. And new colonies will continue to be formed along the coastline.

[elephant seals making various noises]

[elephant seal making repeated honking noise]

[elephant seals making various noises, which continue as Sarah resumes talking]

[Sarah Allen] We also looked at how the animals moved from the main colony to other sub-colonies. So, mortality was high at the main colony, but it wasn't high at the sub-colonies. And that's one of the things that helps us understand how elephant seal colonies expand, because it's not a continuous expansion; it's in pulses. And something like an El Niño event will be a pulse that will force seals to shift to other little sub-colonies where mor...where mortality is lower. They know to shift to these other areas because there have been individual elephant seals that have already gone there.

[elephant seal trumpeting, which sounds like a repeated raspy croak]

[elephant seals making various noises, which are faint due to distance and the noise of waves]

[faint elephant seals noises continue as Sarah resumes talking]

[Sarah Allen] Some of the things that we study at Point Reyes Headlands are population dynamics. And that includes: what the sex and age class of the animals are; and how fast the colony is growing; and what are other factors that might limit that growth. The animals don't recognize boundaries.

[elephant seal trumpeting in the distance]

[elephant seals making barking noises, which continue as Sarah resumes talking]

[Sarah Allen] I do advise kayakers, surfers, and other people who are engaged in watersports to avoid these areas where seals congregate on shore, because...there's a higher probability of being bit by a of these areas, than if you were swimming in some other area.

[waves washing ashore, and elephant seals can be faintly heard in the distance]

[Sarah Allen] But there's a lot we don't know about how these animals maneuver underwater. We've...we're just scratching the surface with the satellite telemetry. That, for example, there are 50 yearling elephant seals that showed up at the lifeboat station in a matter of two days at Point Reyes Headlands. Now, tell me, what was the synchrony for all those young elephant seals to show up at Point Reyes Headlands on...on a period of only a couple days. I can't tell you. That's the sort of information we would like to understand better.

[bull elephant seal trumpets as other seals screech, yelp, belch, and sniff]


The second part of the ten-part Science Behind the Scenery documentary featuring Science Advisor Dr. Sarah Allen talking about the northern elephant seal at Point Reyes National Seashore.


5 minutes, 42 seconds


Pacific Coast Science and Learning Center

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