The two mothers, who are also sisters,swapped babies. Or rather, the older sister, Pandora, forced the switch. Theother sister, Calusa, attempted to retrieve her calf several times, but wasunsuccessful.

两位海豚妈妈，同时也是姐妹，她们调换了孩子。或者不如说，是年长的海豚姐姐潘朵拉（Pandora）强迫海豚妹妹调换了她们的孩子。海豚妹妹卡卢萨（Calusa）几度试图要回自己的孩子，但都徒劳而归。

This switch may have "reset theimprinting clock", say King and her colleagues, meaning each calf then hadto learn its adoptive mother's call.

金和她的同事认为，这种调换“可能重置了印记时钟”，这意味着每只小海豚都不得不再次学习养母的呼唤。

It is unusual for a female dolphin to stealanother's calf but it has previously been documented. It is not clear why twosisters who live close together would do so.

海豚妈妈偷取另一只海豚妈妈的孩子非同寻常，但之前就曾有相关记录。至于住得很近的海豚姐妹这样做的原因为何，目前还不为人知。

It may not be as rare as one might think,says co-author Kelly Jaakkola of the Dolphin Research Center. "A femaletaking another's infant has been seen in many wild animal species."

海豚研究中心的项目合作者凯利·贾科拉（Kelly Jaakkola）表示，“这种情况可能并不像人们想象的那样罕见，在很多野生动物物种中，都有雌性夺走他人幼子的情况发生。”

Switching between two mothers is unusual,says King. "However, the two mothers are maternal sisters, so each calfwas then looked after by its 'aunty'. Evolutionarily speaking there are stillfitness benefits in looking after your sister's calf."

金表示，“两位海豚妈妈交换孩子的情况非同寻常，不过，如果两位海豚妈妈是姐妹，那么两只小海豚就将由各自的‘阿姨’照料。从生物进化角度而言，照料姐妹的孩子在适应性方面仍然具有优势。”

When they want to reunite they will whistle

想要重新会合时，它们会发出唿哨

While this behaviour might sound strange,dolphins do have a darker side to them. They have been known to be incestuous,to "rape" and even to kill one another's young. In that light, alittle infant-stealing no longer sounds as bad.

这种行为也许听起来奇怪，但海豚也有阴暗面。人们已经知道，它们会乱伦，会“强暴”甚至杀死年幼的海豚。从这个角度而言，偷小海豚的劣迹也就相形见绌了。

Even a year later, the calves had not beenswapped back to their original mothers.

即使在一年后，被调换的小海豚也没有被交还各自的妈妈。

It may have been too late. By then the calfwould have imprinted on its new mother and now be listening to her call.

也许已经太晚了。这时，小海豚已经学会了新妈妈的印记，现在它们将听从新妈妈的呼唤了。

Fortunately, there was never any physicalaltercation between the mothers. Both babies remained healthy and happy."As they got older, they socialised with both mothers and with eachother," says Jaakkola.

幸运的是，海豚妈妈之间永远不会发生肢体冲撞。两只小海豚也会健康快乐地成长。贾科拉表示，“随着小海豚的长大，它们会与两个海豚妈妈互动，彼此之间也会有互动。”

In a separate new study in the journalBehavioural Processes, King and colleagues identified just how powerful hersignature call is.

每只小海豚都不得不学习养母的呼唤

Each calf then had to learn its adoptivemother's call

在《动物行为过程》（Behavioural Processes）杂志另外一项最新研究中，金和同事发现这种印记十分强大。

Her team wanted to understand how a motherretrieves her calf as it grows up. To do so, they asked a female dolphin toeither fetch an object, such as a ball, or her calf. Only when she went to gether calf did she produce her unique call.

她的团队希望能了解，在小海豚长大时，海豚妈妈怎样才能要回自己的孩子。为此，他们要求海豚妈妈找回一个物体，如找回一个皮球，或者找回自己的孩子。只有在去找回自己的孩子时，海豚妈妈才会发出独特的呼唤声。

It fits in with our understanding ofsignature whistles, says King. "When mothers and calves are separated fromone another and want to reunite, they will produce their signaturewhistle."

金表示，“这与我们对唿哨信号的理解相吻合。海豚妈妈和小海豚彼此分离时，如果想要重新会合，它们就要发出自己的唿哨信号。”