一项对北太平洋虎鲸的研究表明，虎鲸母亲为儿子做出 “终身牺牲”。

The sound of a very close bond. A killer whale mother and son surfacing together, because in orca family life, offspring stay by their mother's side into adulthood.

从这段声音中可以听出虎鲸亲密的母子关系。音频中的虎鲸母子一起浮出水面，因为在虎鲸的家庭生活中，后代直至成年之后一直待在母亲身边。

But sons are particularly dependent on their mums. Well into adulthood, males will demand to be fed fish by their mothers, even though they're much larger than females.

然而，雄性虎鲸尤其依赖于它们的母亲。即便早已成年，雄性虎鲸仍会要求母亲给它们喂鱼，尽管它们远大于雌性虎鲸。

But that close family bond comes at a cost. This new study showed that having a son cut by half a mother's chance of reproducing again in the future. The scientists believe that mothers invest so much of their energy and effort in their male offspring because the biggest, oldest ones tend to father most of the new calves in a killer whale pod. 

但建立这种亲密的家庭关系是要付出代价的。这项新的研究表明，养育一头雄性虎鲸会使虎鲸母亲未来再次生育的几率减半。科学家们认为，虎鲸母亲将如此多的精力投入到雄性后代身上是因为体型最大、最年长的雄性后代往往会成为虎鲸群中大部分新生幼崽的父亲。

As well as providing an insight into the complex, close-knit lives of these marine mammals, the findings could help us protect them. Understanding how much it costs to raise the next generation of orcas is an insight into what these mammals need to survive. 

这些发现不仅能让我们深入了解虎鲸这种海洋哺乳动物复杂而亲密无间的生活，还能帮助我们保护这一物种。了解虎鲸养育下一代所付出的代价让我们更深刻地认识到这类哺乳动物生存的基本所需。

词汇表

bond 关系，纽带
surfacing 浮出水面
offspring 后代
adulthood 成年（期）
reproducing 生育，繁殖
close-knit 亲密无间的

阅读理解：请在读完上文后，回答下列问题。

1. How long do orca offspring stay with their mothers?

2. True or False? Male orcas are much bigger than females.

3. Why do scientists believe orca mothers invest so much in their sons?

4. What benefits could come from the findings of this study?

答案

1. How long do orca offspring stay with their mothers?
Orca offspring stay by their mother's side into adulthood. 

2. True or False? Male orcas are much bigger than females.
True. Males are much larger than females.

3. Why do scientists believe orca mothers invest so much in their sons?
Because the biggest, oldest orcas tend to father most of the new calves in a killer whale pod.

4. What benefits could come from the findings of this study?
As well as providing an insight into the complex, close-knit lives of these marine mammals, the findings could help us protect them.