Recording 70
录音70
You will hear a lecture about a species of bird called New Caledonian crow.
你将听到一段课程，讲的是一种称为“新喀里多尼亚乌鸦”的鸟。
First, you have some time to look at questions 31 to 40.
首先，你有些时间看看第三十一题至第四十题。
Now listen carefully and answer questions 31 to 40.
现在仔细听录音，回答第三十一题至第四十题。
I'm going to talk today about research into a particular species of bird, the New Caledonian crow, whose natural habitat is small islands in the Pacific Ocean.
今天我将讲讲关于一种鸟的研究，这种鸟叫新喀里多尼亚乌鸦，其自然栖息地是咋太平洋的一些小岛上。
And it seems that these crows are exceptionally resourceful.
从研究结果来看，这些乌鸦特别善于随机应变。
Using sticks or other tools to find food isn't unknown among birds and animals.
用小棍子或其它工具来觅食在鸟类或其它动物中也不罕见。
Some chimpanzees, for example, are known to bang nuts on stones in order to break the shell and get at the edible kernel inside.
譬如，人们知道，一些黑猩猩会用石头砸坚果来砸破果壳以取出里面可食用的果仁。
One New Caledonian crow, called Betty, bent some straight wire into a hook and used it to lift a small bucket of her favorite food from a vertical pipe.
一只叫贝蒂的新喀里多尼亚乌鸦，把一些直的金属丝弯成钩子，并用钩子将一篮子她最喜欢的食物从笔直的管道里拉上来。
This experiment was the first time she'd been presented with wire, which makes it very impressive.
这次实验室她第一次碰到金属丝，给人们留下了深刻印象。
Another crow, called Barney, has demonstrated his skill at using sticks to forage for food.
另一只叫巴尼的乌鸦，证明了自己用小棍子觅食的技能。
In one research project, scientists from New Zealand and Oxford set captive New Caledonian crows a three-stage problem.
在另一个研究项目中，来自新西兰和牛津的科学家为捕捉到的新喀里多尼亚乌鸦设置了三步难题。
If they wanted to extract food from a hole, the crows first had to pull up a string to get a short stick, then use that short stick to remove a long stick from a toolbox and finally use the long stick to reach the food.
如果乌鸦想从洞里取出食物，它们得首先拉出一根线，得到一根短棒，然后用这根短棒从工具箱中取出一根长棍，最后用长棍够到食物。
Amazingly, they worked out how to do this successfully.
令人惊讶的是，它们成功弄明白了该怎么做。
Further experiments carried out at Oxford suggest that crows can also use sticks as tools to inspect all sorts of objects, possibly to assess whether or not they present a danger.
在牛津人们进行了进一步实验，证明了乌鸦还能将小棍当作工具来试探其它事物，可能是评估它们有没有危险。
The idea for the experiment came from observing the birds using tools to pick at random objects, such as a picture of a spider that was printed on some cloth.
实验想法源于人们观察到鸟会用工具来戳弄随机目标，例如一张印在布上的蜘蛛图片。
In this research, five pairs of crows, including Barney, underwent tests to see how they would react to a variety of objects, which were carefully chosen so the birds wouldn't be tempted to view them as a possible source of food.
在此研究汇总，人们给五组乌鸦（包括巴尼在内）做了一些测试来看它们对不同的对象会有什么反应。这些对象都是经过精心挑选的，所以鸟儿们不会将其视为可能的食物来源。
As a further precaution, all the crows had been fed beforehand.
所有的乌鸦都已事先喂过食，作为进一步的防护措施。
On eight occasions, a bird's first contact was by using a tool.
在八个场景中，乌鸦用工具进行初步接触。
In all three trials, Barney began by using a stick for inspection.
全部三次测试中，巴尼都用小棍子作事先试探。
One involved a rubber snake.
其中一个对象是橡胶制成的蛇。
First he approached it, but didn't touch it, then retreated to pick up a stick.
巴尼首先靠近了蛇，但没有碰到它，接着撤回去叼起小棍子。
He then prodded it with the stick.
接着巴尼用小棍子戳了一下橡胶蛇。
After some more investigation, he discarded the stick and carried on pecking at the snake more confidently, apparently convinced that it wouldn't move.
经过一些查探后，巴尼把小棍子扔到一边，更有自信地啄那条橡皮蛇——很显然，巴尼相信蛇不会动。
In other experiments, two different birds, called Pierre and Corbeau, also made a first approach with tools on three separate occasions.
在其它实验中，两只不同的鸟，皮埃尔和科布，也在三个独立场景中也都用了工具进行初次接触。
Pierre used a short piece of wood chip to touch a light which was flashing, and Corbeau was seen prodding a metal toad with a stick.
皮埃尔用了一小段木片来触碰一盏闪烁的灯，科布则用一根小棍戳一只金属蟾蜍。
Significantly, the crows tended to use the sticks only to make their first contact with the object.
很重要的是，乌鸦倾向于仅在初次与对象接触中使用小棍子。
Subsequently, they either ignored the object or dropped the tool and pecked at the object, which is very different from using the tool to get access to food.
随后，乌鸦要不就无视了该对象，要不就把工具丢到一边，然后用喙猛啄该对象，这和用工具觅食有很大不同。

So what conclusions can be drawn from the research?
从这项研究中，能得出什么结论呢？
Evidence is building up from experiments such as these that the birds are able to plan their actions in advance, which is very interesting for understanding their cognition.
这些及其类似的实验都提供证据表明，鸟类有能力提前计划自己的行动，这对于理解鸟类认知能力来说非常有趣。
They don't seem to be responding in a pre-programmed sort of way.
鸟类的反应似乎不是预先设定好的。
It may even be possible that they're able to view a problem and work out what the answer is.
更可能的情况是，鸟类有能力观察问题，然后想出解决方法。
However, a major difficulty is assessing whether this tool-using behavior is a sign of intelligence.
不论如何，主要的难题在于评估这种使用工具的行为是否智力的体现。
To some extent, this is related to the ecological circumstances in which the animal is found.
某种程度而言，这和动物所处的生态环境也有关系。
So scientists want to find out much more about how the crows behave in their native habitat, and a team from Exeter and Oxford universities is carrying out research in New Caledonia.
所以科学家希望了解更多乌鸦在天然栖息地（环境下）的表现，来自埃克塞特大学和牛津大学的研究队伍在新喀里多尼亚进行了一些调研。
They're looking into whether the birds' way of searching for food gives them any possible evolutionary advantage.
他们探究的是鸟类的觅食方式能否作为它们的进化优势。
The birds are hard to observe, as they live in a region of mountainous forest, so the researchers have attached tiny cameras to the tails of some birds, as one method of investigating their behavior.
要观察到这些鸟类实在很困难，因为乌鸦们生活在山区森林中，所以研究人员得在一些鸟的尾部安装上微型照相机来调查它们的行为。
The birds are masters at using sticks to find their food, in particular beetle larvae from the trees.
这些乌鸦非常精通于用小棍子觅食，特别是寻找树上的甲虫幼虫。
It's possible that the birds can derive so much energy from these grubs that they only need to eat a few each day.
可能的情况是，乌鸦能从这些食物（甲虫幼虫）中吸收到大量能量，所以它们一天只需要吃几只甲虫即可。
This would mean that they wouldn't have to spend most of their waking time searching for food, as most animals do.
这意味着，它们不需要花费大量的时间来觅食，大部分动物则需要这么做。
The beetle larvae have a distinct chemical make-up, which can be traced through the feathers and blood of birds that eat them.
甲虫幼虫的化学成分非常特殊。以此为食的鸟，其羽毛和血液中都能追踪到甲虫的特征。
Scientists have collected samples from crows in order to estimate the proportion of larvae in their diet.
科学家从乌鸦上收集到了一些样本，以估计甲虫幼虫在其食物中所占比例。
They should then be able to gauge the extent to which individual birds depend on using sticks to feed themselves.
然后科学家应该就能估计出一只鸟在多大程度上依赖使用小棍子来喂饱自己了。
We've learnt a great deal about the ability of New Caledonian crows to use tools, and some very interesting research is being carried out into them.
从新喀里多尼亚乌鸦使用工具的能力中，我们学到了许多知识，而且在此领域，人们还做了一些很有趣的研究。