VOA慢速英语--研究人员发现加蓬森林大象计数的新方法

Researchers Find New Way to Count Gabon Forest Elephants

Some African elephants live in grassy¹ open areas called savannas³. Scientists can easily count the number of savanna² elephants from an airplane because there are very few trees.

But other African elephants live in dense⁴ forests. Forest elephants are shy and especially hard to find.

The Central African country of Gabon is home to two-thirds of all African forest elephants. The forests in Gabon are extremely dense. That makes it hard to know exactly how many forest elephants there are.

But scientists have found a new way to count them. They use evidence that the animals leave behind. In other words, they look for elephant waste.

Researchers collected waste samples over a period of three years. The researchers walked about 12 kilometers each day. They looked for waste as well as other signs of elephants, including footprints and broken trees. They tested the waste samples for DNA⁵.

They learned that in Gabon, there are about 95,000 forest elephants. Earlier estimates were much lower, at 50,000 to 60,000.

Even with the new information, the International Union for Conservation of Nature believes the population of forest elephants in Central Africa has dropped sharply⁶. It estimates the numbers have decreased by 86 percent in the last 31 years. Forest elephants are threatened by land clearing and by hunters.

The researchers who worked on the new elephant count said the animals live throughout Gabon, covering 90 percent of the total surface area.

Almost 90 percent of the country is covered in forest.

Emma Stokes is the area director for the Wildlife Conservation Society. She said Gabon is "very unique," or special, because elephants can be found in so much of the country.

During their counting efforts, the researchers looked for fresh waste. Sometimes, they would find elephant waste that was too old to be used as evidence.

When they found a sample, they put it in a small glass container. They sent the containers to a laboratory in Libreville, Gabon's capital. Scientists looked at about 2,500 samples.

The samples had to be processed first to remove impurities⁷ or organisms that could affect results.

Stephanie Bourgeois⁸ was one of the writers of a published study about the elephant count. She said the DNA helped the scientists estimate how many different elephants lived in the area that the samples came from.

It is the first elephant count in Gabon in 30 years. The last count only looked at 14 percent of the area in which elephants live.

John Poulsen is an ecologist at Duke University in the state of North Carolina. He was not involved in the elephant research. He said the results of the count are "exciting" because the population estimate rose and because researchers proved a new way of counting elephants can work.

A similar method is being used for tigers in India.

Poulsen added, however, that Gabon's government now has a greater responsibility to keep the forest elephants safe.

Lee White is Gabon's minister of water and forests. He said 65 to 70 percent of all African forest elephants live in Gabon. He called it a "tragedy" that other Central African countries have not been able to save their elephants.

He noted⁹ that the nations that have not been able to keep their elephants safe have suffered civil wars.

At the recent United Nations climate change meeting held in Scotland, White said Gabon still has problems ahead. He believes climate change has reduced the amount of fruit available in the country's forests. Because of this, the elephants are seeking out food from farms. This creates a conflict between people and elephants. About 10 people die each year from such conflicts.

"It looks like climate change is starting to impact the forest," White said. "And that means the elephants are hungry."

Words in This Story

footprint – n. a track or mark left by a foot or shoe

DNA – n. a substance that carries genetic¹⁰ information in the cells of plants and animals — often used before another noun

tragedy – n. a very sad, unfortunate, or upsetting situation : something that causes strong feelings of sadness or regret

exciting – adj. causing feelings of interest and enthusiasm

1 grassy   

adj.盖满草的；长满草的

参考例句：

• They sat and had their lunch on a grassy hillside.他们坐在长满草的山坡上吃午饭。
• Cattle move freely across the grassy plain.牛群自由自在地走过草原。

2 savanna   

n.大草原

参考例句：

• The savanna is also the home of meat-eaters--the lion,leopard,and hyena who feed on the grasseaters.大草原也是食肉动物的家乡--狮子、豹、鬣狗--它们都是以草食动物维持生命的。
• They sped upon velvet wheels across an exhilarant savanna.他们的马车轻捷地穿过一片令人赏心悦目的大草原。

3 savannas   

n.（美国东南部的）无树平原( savanna的名词复数 )；（亚）热带的稀树大草原

参考例句：

• Therefore the jungles and the savannas know of no juvenile delinquency! 因此，丛林和荒原里没有“少年犯罪。” 来自辞典例句
• My soul flits away into the virgin forests and to the savannas. 我的灵魂飞向森林中的处女地和广漠的平原。 来自互联网

4 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

5 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

6 sharply   

adj.锐利地，急速；adv.严厉地，鲜明地

参考例句：

• The plane dived sharply and rose again.飞机猛然俯冲而后又拉了起来。
• Demand for personal computers has risen sharply.对个人电脑的需求急剧增长。

7 impurities   

不纯( impurity的名词复数 )； 不洁； 淫秽； 杂质

参考例句：

• A filter will remove most impurities found in water. 过滤器会滤掉水中的大部分杂质。
• Oil is refined to remove naturally occurring impurities. 油经过提炼去除天然存在的杂质。

8 bourgeois   

adj./n.追求物质享受的(人)；中产阶级分子

参考例句：

• He's accusing them of having a bourgeois and limited vision.他指责他们像中产阶级一样目光狭隘。
• The French Revolution was inspired by the bourgeois.法国革命受到中产阶级的鼓励。

9 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

10 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。