El Niño takes its toll on penguins
By Environmental News Network staff
(ENN) -- Add the Galapagos penguin to the steadily growing list of species whose numbers have significantly declined because of El Niño-related events.
The increasing number and strength of warm-water El Niño events, along with a decline of colder-water La Niña events, have reduced the population of Galapagos penguins by half since 1970, says researcher Dee Boersma, a University of Washington zoology professor and a leading authority on temperate- and equatorial-zone penguins.
Boersma just returned from the Galapagos Islands off of Ecuador in South America. There to examine the impacts of the current El Niño, she discovered dead marine iguanas and sea lions, undernourished flightless cormorants and a generally emaciated penguin population in which no juveniles were seen.
"What that suggests is that none of the penguins bred in the last six months, or if they did breed none of (the chicks) survived to become adults," she says.
In the equatorial Pacific Ocean surrounding the islands, Boersma measured water temperatures of 83 to 84 degrees Fahrenheit, which are much warmer than usual and too warm to sustain the food supply for animals that normally feed in the water.
"To put it simply," says Boersma, "the water's too warm and there's not enough food."
"The islands were very lush, green and verdant, which is unusual," Boersma said. "It's like the ocean is the desert right now and the land is the garden. It's usually the other way around."
Boersma is concerned that the increased intensity and frequency of El Niño events, combined with fewer and milder La Nina events, could continue reducing the islands' penguin population.
"I'm certainly not at all convinced that the Galapagos penguin is going to go extinct because of this," Boersma said. "But I am concerned that the numbers are going to become increasingly low, and we know that with smaller populations they're just more vulnerable to extinction."
The flightless birds typically stand 20 to 24 inches high and weigh 4 to 5 pounds. They live primarily on two islands in the Galapagos Archipelago off the coast of Ecuador. Since they can range to the northernmost reaches of the chain, above the equator, they are the only penguins whose natural habitat is in the Northern Hemisphere.
Boersma says the birds' current population is likely in a range of 4,250 to 8,500, half the total when she first studied their population and nesting patterns in the early 1970s.
There are two primary reasons for the population decline, both linked to food shortages because of El Niño, Boersma says. In some instances, adults simply don't attempt to lay eggs. In other cases, they don't have enough food to sustain themselves and so they abandon their nests.
The situation is complicated further by increasing human activity in the islands. More boats increase the likelihood of oil dumping, Boersma says, and a larger number of people engaged in fishing make it more likely for penguins to get caught in the nets.
However, the Galapagos are protected by a 50-mile protection zone and there is great care taken to keep human impacts in the area down to a minimum.
The penguins' sharpest population decline appears to have come during the El Niño of 1982-83, the strongest recorded before the current El Niño started.
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