Killer whale moms are still supporting their adult sons — and it's costing them

 

Killer¹ whale moms are still supporting their adult sons — and it's costing them

Transcript²

A new study finds that orca mothers still feed their adult sons. It's a bond that may come with costs, researchers say.

"These two have an extremely close social relationship," says Michael Weiss, the research director at the Center for Whale Research in Friday Harbor, Washington.

It's hard for Weiss to think of a time when he didn't catch the pair hanging out in the same group, and often immediately next to each other.

"[They're] just this pair of whales that are basically each other's best friend," he said.

Whales Get A Break As Pandemic Creates Quieter OceansENVIRONMENT

Whales Get A Break As Pandemic Creates Quieter OceansWeiss has observed the mom and son pair spending a lot of time close together, touching³ and floating at the surface — and sharing salmon⁴.

Male orcas are massive, and so are their appetites. They're also less maneuverable, which may make it harder for them to catch prey⁵. All this means that a male like K35 needs help getting enough food.

So his mom will often dive down, says Weiss, "catch a salmon, and bring it up to the surface and actually bite half of the fish off and leave that half for her son. So she's sharing a huge amount of food."And here's the striking thing — since K35 was born two decades ago, his mom has never had another calf⁶. Contrast that with other females in the population.

"Some whales started reproducing at the same age around the same time," says Weiss, "and they had daughters. And they've produced three or four offspring."Mysterious Type Of Killer Whale, Sought After For Years, Found In Southern OceanANIMALS

Mysterious Type Of Killer Whale, Sought After For Years, Found In Southern OceanIt's not just K16. In a paper out this week in the journal Current Biology, Weiss and his colleagues looked back across four decades of life history records of Southern Resident killer whales in the Pacific Northwest. The trend was clear:

"Killer whale mothers pay a really huge cost to take care of their sons," says Weiss. That cost is that they have fewer offspring. "And they do this throughout their son's life and never really stop paying that cost to keep their sons alive."In fact, when a mom dies, her son usually perishes within a year or two. "We think that is largely because they're seeing a huge reduction in the amount of food they get," explains Weiss.

Weiss can't think of another animal that makes this never-ending investment when it has the option of reproducing multiple times. So why would these orca moms sacrifice so much for their sons? Weiss argues the potential payoff is huge.

"K35 is now one of our biggest males in the population," says Weiss. "He's grown big and healthy and looks good."That means he's ready to become a father.

"Honestly, I wouldn't be surprised if some of the next few calves⁷ that get popped out in the population are his," says Weiss.

The result is that his mom would become a grandmother multiple times over. Her genes⁸ would end up in a bunch of calves. And because they'll be born into other pods, she wouldn't have to spend any effort raising them.

"It's an amazing piece of work," says Eve Jourdain, the director of the Norwegian Orca Survey. Jourdain, who wasn't involved in the study, is hoping to conduct a similar research project in Norway.

Orcas take down a blue whale, proving they're the apex⁹ predators¹⁰ of the oceanANIMALS

Orcas take down a blue whale, proving they're the apex predators of the ocean"There could be direct comparisons possible across populations," says Jourdain. "And only then can we start getting a better understanding of how important it is for the conservation of those different populations."It's worth mentioning that this strategy of moms investing so much in their sons has a dark side. Southern Resident killer whales like K16 and K35 are in trouble. In recent years, the population has cratered¹¹ to just 73 animals. And what these orcas really need right now is more reproductive females.

"That's how you keep a population of slow-breeding animals going," says Weiss. "So investing in sons for a population like ours that is so stressed is really not ideal."Weiss worries that this maternal¹² strategy, which served this population so well in the past, could raise their risk of extinction¹³ — that the kind of lifelong bonds he's seen between K16 and her son may tether these creatures to an uncertain fate.

1 killer   

n.杀人者，杀人犯，杀手，屠杀者

参考例句：

• Heart attacks have become Britain's No.1 killer disease.心脏病已成为英国的头号致命疾病。
• The bulk of the evidence points to him as her killer.大量证据证明是他杀死她的。

2 transcript   

n.抄本，誊本，副本，肄业证书

参考例句：

• A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
• They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。

3 touching   

adj.动人的，使人感伤的

参考例句：

• It was a touching sight.这是一幅动人的景象。
• His letter was touching.他的信很感人。

4 salmon   

n.鲑，大马哈鱼，橙红色的

参考例句：

• We saw a salmon jumping in the waterfall there.我们看见一条大马哈鱼在那边瀑布中跳跃。
• Do you have any fresh salmon in at the moment?现在有新鲜大马哈鱼卖吗？

5 prey   

n.被掠食者，牺牲者，掠食；v.捕食，掠夺，折磨

参考例句：

• Stronger animals prey on weaker ones.弱肉强食。
• The lion was hunting for its prey.狮子在寻找猎物。

6 calf   

n.小牛，犊，幼仔，小牛皮

参考例句：

• The cow slinked its calf.那头母牛早产了一头小牛犊。
• The calf blared for its mother.牛犊哞哞地高声叫喊找妈妈。

7 calves   

n.(calf的复数)笨拙的男子，腓；腿肚子( calf的名词复数 )；牛犊；腓；小腿肚v.生小牛( calve的第三人称单数 )；（冰川）崩解；生（小牛等），产（犊）；使（冰川）崩解

参考例句：

• a cow suckling her calves 给小牛吃奶的母牛
• The calves are grazed intensively during their first season. 小牛在生长的第一季里集中喂养。 来自《简明英汉词典》

8 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

9 apex   

n.顶点，最高点

参考例句：

• He reached the apex of power in the early 1930s.他在三十年代初达到了权力的顶峰。
• His election to the presidency was the apex of his career.当选总统是他一生事业的顶峰。

10 predators   

n.食肉动物( predator的名词复数 )；奴役他人者（尤指在财务或性关系方面）

参考例句：

• birds and their earthbound predators 鸟和地面上捕食它们的动物
• The eyes of predators are highly sensitive to the slightest movement. 捕食性动物的眼睛能感觉到最细小的动静。 来自《简明英汉词典》

11 cratered   

adj.有坑洞的，多坑的v.火山口( crater的过去分词 )；弹坑等

参考例句：

• The surface cratered with the constant dropping of water. 表面因经常滴水而成坑。 来自《现代英汉综合大词典》
• Artillery cratered the roads. 炮击后大路布满了弹坑。 来自《现代英汉综合大词典》

12 maternal   

adj.母亲的，母亲般的，母系的，母方的

参考例句：

• He is my maternal uncle.他是我舅舅。
• The sight of the hopeless little boy aroused her maternal instincts.那个绝望的小男孩的模样唤起了她的母性。

13 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。