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[Sarah Allen] Everything about elephant seals is
fairly remarkable. The really big animals. The 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 we know that from
various
satellite telemetry devices that have been attached to the seals
and that provides that information of how long they stay under water 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 come in to breed
one time per year and that is in the winter months. They come in, 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 thirty 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 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 seal showed up
in Russia on Medny Island which is
part of the Komandorski Islands.
So there's no pressure to prevent elephant seals from expanding into the
areas
and new colonies are being formed. There have been colonies established in the Channel
Islands, and then Año Nuevo probably the most well-known colony because it is on
the mainland and the public can access this colony. That colony was formed
in the early nineteen sixties.
And then the Point Reyes colony, which is really the northernmost colony, was established in
nineteen eighty-one 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.
Sold this last year, two thousand and three there were over four hundred and fifty
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.
We also looked at how the animals move 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 in something like an El Niño event
will be a pulse that will force seals to shift to other little sub-colonies where
mortality
is lower.
They know to shift to these other areas because there have been
individual elephant seals that have already gone there.
Some of the things that we study at Point Reyes Headlands, there's population
dynamics,
and that includes what the sex and age class of 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.
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 shark
off of these areas then if you were
swimming in some other area.
There's a lot we don't know about how these animals
maneuver under water.
We are just scratching the surface
with the satellite telemetry.
But for example, there were fifty 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 a
period of a couple days? I can't tell you.
That's the sort of information we would like to understand better.