AUDIE CORNISH, HOST:
At this time every year, northern elephant seals gather along the California coast. Will Huntsberry visited a colony of some 23,000 seals and sent this audio postcard.
WILL HUNTSBERRY, BYLINE: At Piedras Blancas, it's the beginning of mating season. And the males are trying to figure out who's the strongest.
(SOUNDBITE OF ELEPHANT SEALS GROWLING)
HUNTSBERRY: That sound you hear isn't a diesel engine. It's the sound of war. Sexually mature males have enlarged, floppy noses that help them make the growl. The alphas can weigh 5,000 pounds and be as big as a car. When they fight, it's ugly. They lift their bulky bodies high in the air and then strike hard at each other with their teeth.
(SOUNDBITE OF ELEPHANT SEALS GROWLING)
HUNTSBERRY: The fighting has big consequences. Those who win will end up with harems of around 20 to 30 females. But...
RON KAUTZ: Less than 2 percent of all the males born will ever mate.
HUNTSBERRY: That's Ron Kautz. He's a volunteer tour guide. The males, he says, will spend their whole lives practicing these fighting skills, maybe to no avail.
KAUTZ: Usually what happens is that one of them will decide - OK, you win. And they'll back off.
UNIDENTIFIED CHILD #1: How old is that one right there?
KAUTZ: Which one?
HUNTSBERRY: Two young brothers had some pressing questions for Kautz.
UNIDENTIFIED CHILD #1: What do the elephant seals eat?
UNIDENTIFIED CHILD #2: I think I know - crabs.
KAUTZ: No, they eat a few crabs. But mostly, they eat squid and octopus and skates and rays...
HUNTSBERRY: Right now, the seals aren't actually eating anything. They migrate to Alaska twice each year to do all their feeding. During January and February here on the coast, the mothers will birth their pups and then breed with the alpha males. Each seal then leaves the beach on its own to undertake a solo journey several thousand miles back to Alaska.
KAUTZ: Even when the pups leave here, they leave here one at a time.
HUNTSBERRY: The pups leave by themselves?
KAUTZ: Yeah.
HUNTSBERRY: They just know?
KAUTZ: Yeah. Instinct says it's time to go. If you're ever going to eat again - you can't live off mom's milk forever.
HUNTSBERRY: Tough lesson.
For NPR News, I'm Will Huntsberry.