海豚媽媽母愛博大 有換子而養的現象(下)

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.

兩位海豚媽媽，同時也是姐妹，她們調換了孩子。或者不如說，是年長的海豚姐姐潘朵拉（Pandora）強迫海豚妹妹調換了她們的孩子。海豚妹妹卡盧薩（Calusa）幾度試圖要回自己的孩子，但都徒勞而歸。

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

金和她的同事認爲，這種調換“可能重置了印記時鐘”，這意味着每隻小海豚都不得不再次學習養母的呼喚。

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.

海豚媽媽偷取另一隻海豚媽媽的孩子非同尋常，但之前就曾有相關記錄。至於住得很近的海豚姐妹這樣做的原因爲何，目前還不爲人知。

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."

海豚研究中心的項目合作者凱利·賈科拉（Kelly Jaakkola）表示，“這種情況可能並不像人們想象的那樣罕見，在很多野生動物物種中，都有雌性奪走他人幼子的情況發生。”

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，“兩位海豚媽媽交換孩子的情況非同尋常，不過，如果兩位海豚媽媽是姐妹，那麼兩隻小海豚就將由各自的‘阿姨’照料。從生物進化角度而言，照料姐妹的孩子在適應性方面仍然具有優勢。”

When they want to reunite they will whistle

想要重新會合時，它們會發出唿哨

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.

這種行爲也許聽起來奇怪，但海豚也有陰暗面。人們已經知道，它們會亂倫，會“強暴”甚至殺死年幼的海豚。從這個角度而言，偷小海豚的劣跡也就相形見絀了。

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

即使在一年後，被調換的小海豚也沒有被交還各自的媽媽。

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

也許已經太晚了。這時，小海豚已經學會了新媽媽的印記，現在它們將聽從新媽媽的呼喚了。

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.

幸運的是，海豚媽媽之間永遠不會發生肢體衝撞。兩隻小海豚也會健康快樂地成長。賈科拉表示，“隨着小海豚的長大，它們會與兩個海豚媽媽互動，彼此之間也會有互動。”

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

每隻小海豚都不得不學習養母的呼喚

Each calf then had to learn its adoptivemother's call

在《動物行爲過程》（Behavioural Processes）雜誌另外一項最新研究中，金和同事發現這種印記十分強大。

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.

她的團隊希望能瞭解，在小海豚長大時，海豚媽媽怎樣才能要回自己的孩子。爲此，他們要求海豚媽媽找回一個物體，如找回一個皮球，或者找回自己的孩子。只有在去找回自己的孩子時，海豚媽媽纔會發出獨特的呼喚聲。

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，“這與我們對唿哨信號的理解相吻合。海豚媽媽和小海豚彼此分離時，如果想要重新會合，它們就要發出自己的唿哨信號。”