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PRI's Environmental News Magazine

Whales vs. Gulls

Air Date: Week of January 15, 1999

In southern Argentina, one of the rarest whales in the world - the Right Whale - is under siege. Sea gulls have inexplicably begun to gouge out chunks of the whales' flesh when the mammal comes to rest on the surface. Rachael Anne Goodman visited Argentina's Penisula Valdes, the site where researchers first noted the gulls' strange behavior.

Transcript

KNOY: It's Living on Earth. I'm Laura Knoy. In southern Argentina, one of the rarest whales in the world, the right whale, is under siege. Its enemy is a species of sea gull. The birds have inexplicably begun to gouge out chunks of the whales' flesh. These gull attacks have increased so sharply that scientists fear right whales will abandon these breeding grounds altogether. Rachel Anne Goodman visited Argentina's Peninsula Valdes, the site where researchers first noticed the gulls' strange behavior.

(A whale blows)

WOMAN: Hello.

(Many admiring voices)

GOODMAN: In the shallow gulf waters off Peninsula Valdes, 600 miles south of Buenos Aires, whale watchers get a close-up view of one of the largest creatures on Earth. A 60-ton right whale mother and her calf circle the boat.

CHILD: Oh, man.

GOODMAN: These tourists are witnessing a rare sight. There are only 2,300 southern right whales left, about 1% of their original population.

(A whale blows)

GOODMAN: Their slow, gentle demeanor and thick blubber made them the right whale to hunt. Now, those same qualities have attracted a new tormentor.

WOMAN: Do you see his eyes?

(Children ooh and aah)

GOODMAN: Just over a decade ago, scientists began noticing large, concave lesions on the whales' backs. They think they're caused by kelp gulls who land on the resting whales and peck out pieces of blubber and skin. Now researchers from Boston's Whale Conservation Institute have set up a research project to find out what's going on.

WOMAN: Try and maneuver yourself. Do you want the small chair?

WOMAN 2: No, there's enough room; I just didn't see a whale over there.

GOODMAN: In a rickety tin shack perched 100 feet above the Bay of Gulfo Nuevo, biologist Kim Marshall-Tilas and her assistants set up three spotting scopes. They move gingerly in the cramped quarters, but they have a panoramic view of the whales' domain.

WOMAN: And then they're going that way...

GOODMAN: Soon they each have a whale in their sights.

TILAS: The main thing for them to do is to keep their eyes on the same whale, not change. And then, if gull attacks happen, record that they happened during that interval.

(Beeping sounds)

GOODMAN: For the first hour the whales do little more than sleep, floating on the surface like giant hippos, only their backs exposed.

WOMAN: Aah! Gull attack.

GOODMAN: Finally patience pays off. The whale Kim's assistant is watching flinches as a gull pecks its smooth underside.

(To assistant) The gull attacked the belly?

ASSISTANT: Yes.

GOODMAN: Have you seen them attack the bellies a lot?

ASSISTANT: Yes.

GOODMAN: Really?

ASSISTANT: Yes.

TILAS: So you know, when we did this intensive study three years ago, they didn't attack the bellies. The whales were using belly-up behavior as an avoidance.

GOODMAN: It seems as fast as the whales learn to avoid them, the gulls learn a new trick.

TILAS: What our studies showed was that the whales are spending 20% of their day fleeing gull attacks, when they should be spending 100% of their day, you know, resting and working with their babies and playing and feeding.

HARRIS: Eventually they could drive whales out of areas if the attacks become too frequent.

GOODMAN: Graham Harris once spent five years living at this whale camp. Now he's executive director of the Patagonian Nature Foundation, a nonprofit wildlife conservation group. Because southern right whales fast while in their calving grounds at Peninsula Valdez, survival depends on conserving energy and blubber reserves for the long journey back to their feeding grounds near Antarctica. Scientists worry these reserves will be depleted and calves will be underweight if the whales spend their energy avoiding gulls.

(A boat motor. A woman yells, "Come on!")

GOODMAN: Hoping to get a closer view, Kim, her husband Tom, and I head out on the bay in search of whales. Two hundred feet from shore, Tom cuts the motor and the light chop of waves jostles our tiny craft. We soon realize we're not alone at here.

(A whale blows)

TILAS: We're seeing a mother and calf.

GOODMAN: Swimming up to greet us, the mother's broad shiny back looks like a Navy submarine surfacing, our boat a mere bath toy in comparison. Her calf seems equally curious, circling our boat.

(Blow sounds)

GOODMAN: Then the kelp gulls appear.

T. TILAS: There's an attack. He's landed right on the back of the animal and he's pecking, and the animal is reacting by arching his back and rolling.

GOODMAN: Suddenly a small black and white bird lands on the mother's back and rips a piece of skin out with its beak. In minutes, mother and calf are gone beneath the waves.

K. TILAS: It's got to be like a horse fly, where you don't really notice it, you don't notice it lands on you, and then all of a sudden it's, Ouch!

GOODMAN: Like some Alfred Hitchcock horror movie, the birds have turned bloodthirsty. And the rate of attacks is climbing steadily. So, why the change in behavior? Scientists think it could be a learned behavior that is being spread by word of mouth or beak through a gull population that's more than doubled in size in the past decade. And they think there's a human link in this new food chain.

(Gull calls)

GOODMAN: At the nearby Puerto Madryn City Dump, clouds of kelp gulls swarm around uncovered gravel pits full of rotting fish waste. The powerful stench attracts birds like flies to a carcass.

(Gull calls)

GOODMAN: This bonanza of free food is the leftovers of a booming fish-processing industry. The huge waste piles have caused an overpopulation of gulls, which is affecting not only whales but also other birds, such as terns and cormorants. Gulls prey on their chicks and compete for nesting sites. Flavio Quintana is a wildlife biologist with the Central Patagonia Research Center, a government-funded science institute.

QUINTANA: Unfortunately, we don't have a regulation for dump management. We don't really understand why the government doesn't take measures to control this dump.

GOODMAN: Dr. Quintana says he and his colleagues have written letters, but local officials have shown little interest in taking action. He says if the fish dumps were covered, the gull population would naturally balance itself out. Short of that, there's talk of shooting gulls as a last resort, but researchers don't even know if population control is the answer. It could be the perpetrators are only a few crafty individuals.

TILAS: What we're hoping to do, we've been trying to do for the last 2 years, is use an explosive net to go over the gull roosting areas so we can actually entrap 150 gulls at a time, and color them, mark them with different colors. And the study would proceed where at each roost area, scientists would watch what gulls were doing what. And if the red gull keeps going back to the whale and the other ones don't, we'll know that it's a learned behavior and we can deal with it from another angle.

GOODMAN: But so far, the money for that research hasn't been found.

(More voices at whale watch. Woman: "There's the tail!")

GOODMAN: Back on the tourist boat, groups of school children are ecstatic to be a few feet from a southern right whale. Right whales are making a slow recovery from the brink of extinction at the hands of whalers, but they're still in trouble from the indirect effects of human activity on the sea. Peninsula Valdes is one of only 2 places on Earth where these whales still come to give birth. And scientists working here fear that if something isn't done about the fish waste and the gulls it attracts, the whales could abandon Peninsula Valdes altogether. That could jeopardize their recovery and make scenes like this a thing of the past.

(Voices at whale watch)

GOODMAN: For Living on Earth, I'm Rachel Anne Goodman in Peninsula Valdez, Argentina.

 

 

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