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AS IT IS - Penguins Missing from Major Breeding Ground

更新时间:2019/4/29 19:42:49 来源:本站原创 作者:佚名

For the past three years, very few emperor penguins have produced baby penguins at the place they usually breed. A new study found that the same is true this year at Antarctica’s second biggest breeding grounds.

Scientists use satellite images to look at penguin groups in Antarctica. Most years, there are 15,000 to 24,000 pairs of emperor penguins that come to a breeding site on the ice at Halley Bay. Until recently, researchers have considered this area to be safe from experiencing warming temperatures – and melting ice – during this century. Emperor penguins breed only on sea ice. So, once ice melts in a place, they can no longer breed there.

According to a study released this week in Antarctic Science, almost no emperor penguins have been seen at Halley Bay since 2016.

The number of breeding pairs, male and female penguins, that raise their chicks together, has gone up quickly at a nearby breeding ground called Dawson-Lambton. Yet, the study’s writer said that number is not the same as the number of penguins usually seen at Halley Bay.

Phil Trathan is head of conservation biology at the British Antarctic Survey. “We’ve never seen a breeding failure on a scale like this in 60 years,” he said. “It’s unusual to have a complete breeding failure in such a big colony.”

Normally about 8 percent of the world’s emperor penguin population breeds at Halley Bay, Trathan said.

Emperor penguins are black and white, with yellow ears and breasts. They are the largest penguin species. They can weigh up to 40 kilograms and live for about 20 years. Pairs breed in the coldest winter conditions. The male is responsible for incubating the egg for about two months.

Scientists say the sharp drop in numbers is because of climate and weather conditions. Storms, wind and warmer weather break apart the “fast ice” — sea ice that is connected to land. That is where emperor penguins stay to breed. They incubate their egg and care for their chick — one each pair — on ice. After breeding and then feeding the chicks for a few months until they can swim, the penguins move to open sea.

The study found that in 2016 and 2017, there was no breeding activity in Halley Bay. Last year, there were very few pairs.

The nearby Dawson-Lambton breeding area saw fewer than 2,000 pairs in 2015. That number increased to around 11,000 pairs in 2017 and over 14,000 pairs in 2018, the study said.

That means the penguins have not completely disappeared, but it doesn’t account for the total number lost at Halley Bay, Trathan said.

The move of part of the colony to Dawson-Lambton is not the central problem. The real problem is that scientists thought of Halley Bay as a climate change refuge, a place “where in the future you expect to always have emperors,” Trathan said.

Trathan said a super strong El Niño -- a natural cycle of warming in the central Pacific Ocean that changes weather worldwide -- melted more sea ice than usual. Wind and waves hit the ice shelf, or fast ice. That made the breeding home a less secure place to raise chicks.

The breeding colony failure, Trathan said, “is a warning of things that might become important in the future.”

Stephanie Jenouvrier is a penguin expert at Woods Hole Oceanographic Institution who was not involved in the study. She said the study results make sense. A great environmental change can sometimes lead to a breeding failure like this, she said. A 2014 study by Jenouvrier predicted that, because of climate change, the worldwide population of emperor penguins would fall by at least 19 percent by the year 2100.

I’m Jill Robbins.

Words in This Story

breed - v. to produce young animals, birds and so on, or to produce offspring by sexual reproduction

breeding ground – n. a place where animals go to breed

chick - n. a baby bird

scale - n. the size or level of something especially in comparison to something else

incubate - v. to sit on eggs so that they will be kept warm and will hatch (break open and produce young)

refuge - n. a place that provides shelter or protection

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