NARRATOR:Listen to part of a lecture in a biology class.

旁白：请听一段生物课上的讲座。

FEMALE PROFESSOR:So, those are some of the common theories on bird migration.

教授：那么前面是关于鸟类迁徙的一些常见理论。

Now let’s talk about “homing.”

现在让我们谈谈归巢。

Homing is more than just the return flight home from migratory trips——homing can take place at any time and from any location.

归巢不仅仅是从迁徙旅行中飞回家，归巢发生在任何时间和任何地点。

It’s the ability that some birds have of finding their way back to an exact location regardless of their starting point… or how far away they are… or the time of year… and so on.

这是一些鸟类找路并返回一个确切位置的能力，无论起点在哪或距离有多远，或一年中的时段等等。

You’ve all heard of homing pigeons but there are lots of bird species that have highly refined homing skills so maybe there’s some evolutionary advantage.

你们都听说过信鸽，但是有很多鸟类具有高度精细的归巢技能，所以也许它们有一些进化优势。

Why would birds be so good at this? Todd?

陶德，为什么鸟儿会擅长归巢呢？

MALE STUDENT:Well, baby birds stay in the nest while the parents go out and hunt for food.

学生：嗯，亲鸟出去觅食的时候，小鸟留在巢里。

If the parents have to fly all over the place to find the food, they’d need to be able to find the nest again.

如果亲鸟必须到处飞寻找食物，它们需要能再次找到回巢之路。

FEMALE PROFESSOR:And once you’d found food you’d want to get home quickly, wouldn’t you? To feed your young?

教授：一旦找到了食物，你就想快点回家，喂孩子，不是吗？

So you’d want the most direct path home—you wouldn’t want to retrace whatever winding, meandering path you’d taken while you were searching for food.

所以你想要最直接的回家路，不会想原路返回，沿着寻找食物的时候所走的蜿蜒和徘徊的路径。

Being able to fly home directly is very efficient:the offspring get food faster and their parents are home sooner to look out for them.

能直接飞回家，效率很高，后代能更快地得到食物，亲鸟也更早回家照顾它们。

MALE STUDENT:But, it isn’t just the offspring that benefit—the adult birds get back to a safe place sooner as well.

学生：但受益的不仅仅是雏鸟，成鸟也能尽快回到安全的地方。

FEMALE PROFESSOR:Right. Now, what about finding your way home after going south for the winter?

教授：对的。那么，在南下过冬后如何找到回家路呢？

FEMALE STUDENT:Well, it’d be nice if you could go back to a place you knew was OK.

学生：嗯，能回到一个你很了解的地方，那就很好。

Ya’know, one that’s got water or food…Not too many predators. Some place where you might even still have a nest.

那里有水或食物，又没有太多捕食者，有些地方你甚至可能还有个巢穴。

FEMALE PROFESSOR:Good. Now, so far, we’ve been talking about times when birds intentionally—or, at least instinctively—leave home, but are there other reasons why a bird might find itself away from its nest?

教授：好。到目前为止，我们一直在谈论的情况是，鸟类会有意或本能地离开家，但是还有其他原因导致鸟远离巢穴吗？

FEMALE STUDENT:Birds are vulnerable to really strong winds. Storms could blow them pretty far off course.

学生：鸟类很容易受到强风的影响。暴风雨会把它们吹得很远。

FEMALE PROFESSOR:But finding your way back to your nest when you’ve been accidentally displaced is a little different from getting home after your annual migration to a warmer climate.

教授：但是，当意外离开巢穴时，去找回家的路与每年迁移到温暖区域后回家是有点不同的。

So, do you think all those mechanisms we discussed… that birds use when migrating… apply to homing as well?

那么你认为我们讨论的鸟类在迁徙时使用的所有这些机制也适用于归巢吗？

FEMALE STUDENT:I think so. I mean we talked about using the Sun and the stars as navigational guides—and that would certainly be helpful for homing.

学生：我想是的。我是说，我们谈到了使用太阳和星星作为导航和向导，这肯定有助于归航。

And so would that ability to sense Earth’s magnetic poles—the one in the studies you described about the, um, internal magnetic compass birds have.

因此，有了感知地球磁极的能力，你所描述的关于嗯，内部磁罗盘鸟类的研究中就有这种能力。

Yeah, it should be the same.

是的，应该是一样的。

FEMALE PROFESSOR:OK, so celestial bodies make good navigational aids. Anything else?

教授：好的。所以天体是很好的导航辅助。还有别的吗？

MALE STUDENT:Well, for short distances, you could just memorize the area. Use landmarks. Like, when my friend tells me to turn left after I see the post office to get to his house.

学生：对于短距离，你可以只需记得这区域里，利用地标，比如我的朋友告诉我在看到邮局后左转去他家。

FEMALE PROFESSOR:So, when birds are out searching for food, they can memorize landmarks. Mountains, rivers… who knows, maybe even the post office.

教授：所以当鸟出去寻找食物时，它们可以记住地标：山脉、河流，甚至可能是邮局。

Studies of gannets have shown that this is one way they navigate.

对塘鹅的研究表明，这就是它们导航的一种方式。

Gannets are seabirds so when they wind up in an unfamiliar location over land, they fly in outward spirals until they reach the coast.

塘鹅、海鸟，当它们在陆地上一个不熟悉的位置盘旋时，它们会向外盘旋飞行，直到它们到达海岸。

Then they use the coastline to find their way home.

然后他们利用海岸线找到回家的路。

Of course, when we say that birds “memorize” their terrain—that may not be accurate.

当然，我们说鸟类能记住地形，这可能并不准确。

It’s not always a good idea to use human analogies when trying to understand animal behavior—particularly when it comes to navigation which we, as a species, are spectacularly bad at.

在试图理解动物行为时，去使用人类来类比并不是好主意，特别是在导航方面，我们非常不擅长。

I mean, even with maps, how often do we get lost?

我意思是，即使有地图，我们还是会经常迷路。

But, with birds, they’re actually overengineered to be good at navigation.

但是对于鸟类，它们实际上有很多设计，是以擅长导航。

Just think about all those tools we’ve discussed—celestial bodies, magnetic fields, landmarks—They’ve got a lot of sensory cues at their disposal.

想想我们讨论过的所有这些工具：天体、磁场、地标，它们有很多感官线索可供使用。

But how do they use them?

但它们如何利用的呢？

For example: do birds use one navigational cue at a time… Like being guided by stars when the sky is clear and using magnetic fields when it’s cloudy?

例如，鸟类是否一次使用一个导航工具，例如在天空晴朗时由星星引导，在多云时使用磁场？

Or, do they use all these tools simultaneously—calibrating their location from multiple cues at the same time?

或者它们是否同时使用所有这些工具，同时从多个过程中校准位置？

Does the answer depend on the particular species? This is a really rich subject for research…

答案是否对于特定的物种而不同？这是一个非常丰富的研究课题。

In fact, let’s talk about how you might go about designing some experiments to answer these questions.

让我们谈谈如何设计一些实验来回答这些问题。

Keeping in mind, as I said, that your personal experiences won’t be of much use as you try to come up with hypotheses to test.

请记住，正如我所说，在尝试提出假设进行测试时，你的个人经历不会有太大用处。