北極熊觀察到獵物后會(huì)埋起來，留到以后再吃

北極熊觀察到獵物后會(huì)埋起來，留到以后再吃

Within the Arctic Circle, every now and then, the largest of all bear species hides a hard-earned kill in an icy larder. Just like a squirrel buries its nuts to save for later, polar bears have been observed burying meaty carcasses under the snow. A new study, published in Arctic Science, explores this behavior, finding that while it does occur, it is still pretty rare.

在北極圈內(nèi)，北極熊是所有熊類中最大的一種，時(shí)不時(shí)地會(huì)在冰里藏起一只來之不易的獵物。就像松鼠會(huì)把堅(jiān)果埋起來以備以后吃一樣，北極熊也會(huì)把獵物的尸體埋在雪下。發(fā)表在《北極科學(xué)》雜志上的一項(xiàng)新研究探討了這種行為，發(fā)現(xiàn)盡管它確實(shí)發(fā)生了，但仍然相當(dāng)罕見。

A team led by the University of Alberta set out to determine whether polar bears exhibit caching behavior and how frequently it had been observed. To find out, they trawled through thousands of observations of bears made in Svalbard, Greenland, and Canada between 1973 and 2018.

由阿爾伯塔大學(xué)領(lǐng)導(dǎo)的一個(gè)研究小組開始研究北極熊是否有貯藏食物的行為，以及觀察到這種行為的頻率。為了找到答案，他們查閱了1973年至2018年間在斯瓦爾巴特群島、格陵蘭島和加拿大觀察到的數(shù)千只熊。

“The paucity of observations of wild polar bears (Ursus maritimus) caching of food (including hoarding, i.e., burying and remaining with a kill for up to a few days) has led to the conclusion that such behavior does not occur or is negligible in this species,” the researchers begin their paper. However, they identified 19 instances of polar bears hiding their food, suggesting that although rare, this behavior is very much present in the species.

野生北極熊貯藏食物(包括囤積食物，即不食用動(dòng)物)的觀察很少。研究人員在論文的開頭寫道:“在美國，將尸體掩埋，并將其與獵物一起保持幾天時(shí)間)導(dǎo)致了這樣一個(gè)結(jié)論:這種行為不會(huì)發(fā)生，或者在這個(gè)物種中是微不足道的。”然而，他們發(fā)現(xiàn)了19個(gè)北極熊藏食物的例子，這表明雖然這種行為很罕見，但在這個(gè)物種中卻非常普遍。

“My curiosity about short-term food caching was re-activated by receiving a photo from a friend of a male polar bear lying on the ice with a mostly snow-covered harp seal [image a below],” study leader Dr Ian Stirling told Polar Bears International. “I had seen this kind of behavior only once in over 40 years of research on polar bears. On talking with colleagues… all had seen this behavior, but only rarely.”

研究負(fù)責(zé)人伊恩·斯特靈博士告訴《北極熊國際》雜志:“我收到了一張朋友的照片，照片上是一只雄性北極熊躺在冰面上，旁邊是一只幾乎被雪覆蓋的格陵蘭海豹，這再次激發(fā)了我對(duì)儲(chǔ)存短期食物的好奇心。”“在40多年對(duì)北極熊的研究中，我只見過這種行為一次。在與同事交談時(shí)……所有人都看到過這種行為，但非常罕見。”

Examples of polar bears keeping their snacks a secret from other bears. Stirling et al. 2019/Arctic Science

It appears that hoarding behavior is influenced by features of the prey. A small snack, like a baby seal, will be gobbled down in one, leaving nothing to hoard, but a larger meal, like an adult ringed seal or part of a whale might be covered in snow and guarded by the bear while it takes a break from eating. The researchers think this is to prevent a phenomenon known as kleptoparasitism, which involves fellow bears and other scavengers getting their paws on the prize and stealing it.

囤積行為似乎受到獵物特征的影響。小獵物，比如小海豹，會(huì)被一口吞下，什么也不剩，但大點(diǎn)的食物，比如成年環(huán)斑海豹或鯨魚的一部分，可能會(huì)被雪覆蓋，在熊休息的時(shí)候由它看守。研究人員認(rèn)為，這是為了防止一種被稱為“盜竊寄生蟲癥”的現(xiàn)象，這種疾病會(huì)讓熊同胞和其他食腐動(dòng)物把爪子伸向獎(jiǎng)品并偷走。

The sight of a dark, bloodied carcass is quite an obvious one in a pristine white backdrop, so a covering of snow makes the kill much harder for other animals to spot. They might still be drawn to it by its smell, though. The authors note that bears are more likely to cache their prey when there’s more snow about to cover it. Some polar bears were so keen to cling onto their prey, they were observed burying it multiple times.

在原始的白色背景下，看到一具黑色、血跡斑斑的尸體是相當(dāng)明顯的，因此覆蓋的雪使得其他動(dòng)物很難發(fā)現(xiàn)被獵殺的動(dòng)物。盡管如此，他們還是會(huì)被它的氣味所吸引。作者指出，當(dāng)雪越積越多的時(shí)候，熊就越有可能隱藏它們的獵物。有些北極熊非常喜歡抓住獵物不放，有人看到它們把獵物埋了好幾次。

“When the ship was about 150 meters from the bear, it woke, dragged the carcass out from under its snow covering, left the floe he was on, swam with it to an adjacent floe, and dragged it out of the water,” notes the paper, describing one observation. “Between about 19.30 and 22.30 the bear moved the carcass several times, each time after which he slept briefly, washed his paws, fed, and re-buried the carcass.”

“當(dāng)船離熊大約150米的時(shí)候，它醒了，把尸體從積雪下拖出來，離開他所在的浮冰，游到附近的浮冰上，把它從水里拖出來，”這篇論文描述了一個(gè)觀察結(jié)果。“大約在19點(diǎn)30分到22點(diǎn)30分之間，這只熊移動(dòng)了幾次尸體，每一次之后它都會(huì)短暫地睡上一覺，洗一洗爪子，吃點(diǎn)東西，然后再把尸體埋起來。”

Another bear was sighted with an entire beluga whale calf (it probably found it dead), which it dragged off the beach and covered with grass. One bear was even seen with a half-eaten young polar bear, which it had partially covered with seaweed.

另一只熊被發(fā)現(xiàn)和一整只白鯨幼崽在一起(它可能發(fā)現(xiàn)幼鯨已經(jīng)死了)，它把幼鯨拖出海灘，用草覆蓋著。有人甚至看到一只熊和一只吃了一半的小北極熊在一起，北極熊身上有一部分被海藻覆蓋著。

Caching behaviour has been observed in various bear species, but it’s most common in brown (aka grizzly) bears. The researchers believe that the difference in caching frequency between the two species might be linked to who they share their habitat with. Brown bears have a denser population, and share their forested homes with numerous scavengers like wolves and ravens. Polar bears, meanwhile, are more spread out and only have to deal with the occasional Arctic fox or feathered thief. Nevertheless, when you’re in possession of a whale carcass or a big juicy seal, keeping it secret is always a good idea.

緩存行為在各種熊類中都有發(fā)現(xiàn)，但最常見的是棕熊(灰熊)。研究人員認(rèn)為，這兩個(gè)物種緩存頻率的差異可能與它們與誰共享?xiàng)⒌赜嘘P(guān)。棕熊的種群密度更大，它們與許多像狼和渡鴉這樣的食腐動(dòng)物共同生活在森林里。與此同時(shí)，北極熊更加分散，只需要對(duì)付偶爾出現(xiàn)的北極狐或長有羽毛的小偷。然而，當(dāng)你擁有一具鯨魚尸體或一只大而多汁的海豹時(shí)，保守秘密總是一個(gè)好主意。