陆地上的食物似乎不利于北极熊成长
文章来源:未知 文章作者:enread 发布时间:2015-04-02 06:12 字体: [ ]  进入论坛
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A team of scientists led by the U.S. Geological Survey found that polar bears, increasingly forced on shore due to sea ice loss, may be eating terrestrial foods including berries, birds and eggs, but any nutritional1 gains are limited to a few individuals and likely cannot compensate2 for lost opportunities to consume their traditional, lipid-rich prey3 -- ice seals. "Although some polar bears may eat terrestrial foods, there is no evidence the behavior is widespread," said Dr. Karyn Rode, lead author of the study and scientist with the USGS. "In the regions where terrestrial feeding by polar bears has been documented, polar bear body condition and survival rates have declined."
 
The authors detail their findings in a review article in Frontiers in Ecology and the Environment. The scientists noted4 that over much of the polar bear's range, terrestrial habitats are already occupied by grizzly5 bears. Those grizzly bears occur at low densities6 and are some of the smallest of their species due to low food quality and availability. Further, they are a potential competitor as polar bears displaced from their sea ice habitats increasingly use the same land habitats as grizzly bears.
 
"The smaller size and low population density7 of grizzly bears in the Arctic provides a clear indication of the nutritional limitations of onshore habitats for supporting large bodied polar bears in meaningful numbers," said Rode. "Grizzly bears and polar bears are likely to increasingly interact and potentially compete for terrestrial resources."
 
The study found that fewer than 30 individual polar bears have been observed consuming bird eggs from any one population, which typically range from 900 to 2000 individuals. "There has been a fair bit of publicity8 about polar bears consuming bird eggs. However, this behavior is not yet common, and is unlikely to have population-level impacts on trends in body condition and survival," said Rode.
 
Few foods are as energetically dense9 as marine10 prey. Studies suggest that polar bears consume the highest lipid diet of any species, which provides all essential nutrients11 and is ideal for maximizing fat deposition12 and minimizing energetic requirements. Potential foods found in the terrestrial environment are dominated by high-protein, low-fat animals and vegetation. Polar bears are not physiologically14 suited to digest plants, and it would be difficult for them to ingest the volumes that would be required to support their large body size.
 
"The reports of terrestrial feeding by polar bears provide important insights into the ecology of bears on land," said Rode. "In this paper, we tried to put those observations into a broader context. Focused research will help us determine whether terrestrial foods could contribute to polar bear nutrition despite the physiological13 and nutritional limitations and the low availability of most terrestrial food resources. However, the evidence thus far suggests that increased consumption of terrestrial foods by polar bears is unlikely to offset15 declines in body condition and survival resulting from sea ice loss."


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1 nutritional 4HRxN     
adj.营养的,滋养的
参考例句:
  • A diet lacking in nutritional value will not keep a person healthy.缺乏营养价值的饮食不能维持人的健康。
  • The labels on food products give a lot of information about their nutritional content.食品上的标签提供很多关于营养成分的信息。
2 compensate AXky7     
vt.补偿,赔偿;酬报 vi.弥补;补偿;抵消
参考例句:
  • She used her good looks to compensate her lack of intelligence. 她利用她漂亮的外表来弥补智力的不足。
  • Nothing can compensate for the loss of one's health. 一个人失去了键康是不可弥补的。
3 prey g1czH     
n.被掠食者,牺牲者,掠食;v.捕食,掠夺,折磨
参考例句:
  • Stronger animals prey on weaker ones.弱肉强食。
  • The lion was hunting for its prey.狮子在寻找猎物。
4 noted 5n4zXc     
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。
5 grizzly c6xyZ     
adj.略为灰色的,呈灰色的;n.灰色大熊
参考例句:
  • This grizzly liked people.这只灰熊却喜欢人。
  • Grizzly bears are not generally social creatures.一般说来,灰熊不是社交型动物。
6 densities eca5c1ea104bef3058e858fe084fb6d0     
密集( density的名词复数 ); 稠密; 密度(固体、液体或气体单位体积的质量); 密度(磁盘存贮数据的可用空间)
参考例句:
  • The range of densities of interest is about 3.5. 有用的密度范围为3.5左右。
  • Densities presumably can be probed by radar. 利用雷达也许还能探测出气体的密度。
7 density rOdzZ     
n.密集,密度,浓度
参考例句:
  • The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
  • The region has a very high population density.该地区的人口密度很高。
8 publicity ASmxx     
n.众所周知,闻名;宣传,广告
参考例句:
  • The singer star's marriage got a lot of publicity.这位歌星的婚事引起了公众的关注。
  • He dismissed the event as just a publicity gimmick.他不理会这件事,只当它是一种宣传手法。
9 dense aONzX     
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。
10 marine 77Izo     
adj.海的;海生的;航海的;海事的;n.水兵
参考例句:
  • Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
  • When the war broke out,he volunteered for the Marine Corps.战争爆发时,他自愿参加了海军陆战队。
11 nutrients 6a1e1ed248a3ac49744c39cc962fb607     
n.(食品或化学品)营养物,营养品( nutrient的名词复数 )
参考例句:
  • a lack of essential nutrients 基本营养的缺乏
  • Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》
12 deposition MwOx4     
n.免职,罢官;作证;沉淀;沉淀物
参考例句:
  • It was this issue which led to the deposition of the king.正是这件事导致了国王被废黜。
  • This leads to calcium deposition in the blood-vessels.这导致钙在血管中沉积。
13 physiological aAvyK     
adj.生理学的,生理学上的
参考例句:
  • He bought a physiological book.他买了一本生理学方面的书。
  • Every individual has a physiological requirement for each nutrient.每个人对每种营养成分都有一种生理上的需要。
14 physiologically QNfx3     
ad.生理上,在生理学上
参考例句:
  • Therefore, the liver and gallbladder cannot be completely separated physiologically and pathologically. 因此,肝胆在生理和病理上不能完全分离。
  • Therefore, the liver and gallbladder are closely related physiologically and pathologically. 因此,肝胆在生理和病理上紧密联系。
15 offset mIZx8     
n.分支,补偿;v.抵消,补偿
参考例句:
  • Their wage increases would be offset by higher prices.他们增加的工资会被物价上涨所抵消。
  • He put up his prices to offset the increased cost of materials.他提高了售价以补偿材料成本的增加。
TAG标签: foods ice bears
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