'為什麼烏鴉絕對是最聰明的鳥？'

We're sure you have your favourite animal. It may even be a really smart one. But corvids - such as crows, magpies and ravens - really are something special. In fact, they're some of the most intelligent animals in the world.

我們確信你有你最喜歡的動物，它甚至可能是一個非常聰明的動物。但是，烏鴉，喜鵲等鴉科動物確實很特別。事實上，它們是世界上最聰明的動物之一。

And here we've gathered some of the finest examples of just how clever these gorgeous creatures can be.

在這裡，我們收集了一些最優秀的例子來說明這些美麗的生物有多聰明。

1. Crows can reason out cause and effect

1。烏鴉能找出因果關係。

In a test on New Caledonian crows, crows were placed in an enclosure wherein a stick would emerge from a hide. They used two scenarios: in the first, a human was observed entering the hide before the stick moved, and leaving after. In the second, the human remained hidden.

在對新喀里多尼亞烏鴉的測試中，烏鴉被放在一個圍欄裡，在那裡一根棍子會從一個獸皮裡伸出來。他們使用了兩個場景：第一個場景中，觀察到一個人在棍子移動之前進入了獸皮，之後離開。在第二種情況下，人類仍然隱藏著。

In the first, the crows were much more relaxed after the human left, correctly linking the movement of the stick to the presence of the human. They would forage for food, and behave normally. In the second, the crow had no other reference for the stick's presence, so they remained wary.

首先，烏鴉在人類離開後更加放鬆，正確地將棍子的運動與人類的存在聯繫起來。他們會覓食，行為正常。在第二種情況下，烏鴉沒有其他的關於棍子存在的參考物，所以他們保持警惕。

"These results really seem to be showing that crows react in a very similar way to humans in a situation that requires them to reason about a hidden causal agent," says biologist Alex Taylor.

生物學家亞歷克斯·泰勒說：“這些結果似乎真的表明，烏鴉對人類的反應非常相似，在這種情況下，烏鴉需要對隱藏的因果因素進行推理。”

2. Crows understand water displacement

2. 烏鴉懂得水的位移

In an experiment with tubes published in PLOS One, scientists determined that New Caledonian crows can not only tell the difference between water and sand - they also understand water displacement.

在一項發表在PLOS One上的試管實驗中，科學家們發現新喀里多尼亞烏鴉不僅能分辨水和沙的區別——它們還能理解水的位移。

The test involved tubes containing water and a treat floating on top out of reach. The crows filled the tubes with enough rocks or other heavy items to bring the food within reach.

這項測試包括裝有水的管子和漂浮在水面上的處理方法。烏鴉在管子裡裝滿了足夠多的石頭或其他重物，以便把食物帶到伸手可及的地方。

They also were presented with different scenarios, such as tubes with different water levels. The crows showed an absolute preference for the tube that would get them the food with the least amount of work.

他們也有不同的場景，如不同水位的管道。烏鴉對管子表現出絕對的偏愛，因為管子能讓它們以最少的工作量獲得食物。

Their success rate was on a par with seven-year-old children, the researchers said.

研究人員說，他們的成功率與7歲兒童相當。

3. Crows hold a grudge - and pass that grudge on to other crows

3. 烏鴉會懷恨在心——把怨恨傳遞給其他烏鴉。

Ever wonder why crow researchers sometimes wear masks? It's because crows can recognise human faces, especially the faces of humans who have done them wrong.

有沒有想過為什麼烏鴉研究人員有時戴口罩?這是因為烏鴉能認出人的臉，特別是那些做錯了人的臉。

So, if you're trying to record how crows react to negative stimuli (such as being caught and tagged), you don't want to do that using your real face. If you do, you'll get loudly scolded by the agitated flock every time you approach, as biologist John Marzluff discovered and detailed in a 2011 paper.

所以，如果你試圖記錄烏鴉對負面刺激的反應(比如被抓到並貼上標籤)，你就不想用你真實的臉來做這件事。如果你這樣做了，你每次接近時都會被激動的羊群大聲責罵，生物學家約翰·馬茲魯夫在2011年的一篇論文中發現並詳細描述了這一點。

Good thing he did, too. A few years later, he found out that crows not only hold onto that grudge - they tell other crows about it, too.

他也做了件好事。幾年後，他發現烏鴉不僅會記仇，還會告訴其他烏鴉。

Within the first two weeks after trapping, around 26 percent of crows scolded the human wearing the danger mask. Around 15 months later, that figure was 30.4 percent.

在被困的頭兩週內，大約26%的烏鴉會責罵戴著危險面具的人。大約15個月後，這個數字是30.4%。

Three years after the initial trapping event, with no action towards the crows since, the number of scolding crows had grown to 66 percent.

在最初的誘捕事件發生三年後，沒有對烏鴉採取任何行動，責罵烏鴉的數量已經增長到66%。

4. Crows hold funerals for their dead

4。烏鴉為死者舉行葬禮

When a crow dies, other crows are often observed gathering around and making a lot of loud noise - much like humans, really. The reason for this was unknown until 2015, when crow researcher Kaeli Swift crowdfunded research to try and figure out why.

當一隻烏鴉死後，人們經常會看到其他的烏鴉聚集在一起，發出很大的噪音——真的很像人類。原因一直不清楚，直到2015年，烏鴉研究者KaeliSwift眾籌研究，試圖找出原因。

Her conclusion, published in the journal Animal Behaviour, was that crows gather around their dead fellows to learn about danger.

她的結論發表在《動物行為》雜誌上，是烏鴉聚集在死去的同伴周圍，是為了瞭解危險。

And it works. The city of Chatham, Ontario is beneath a crow migration route, and they plague the town on their way through. Every attempt to get rid of them has failed - including shooting at them with pellet guns. The crows learnt how to fly just high enough to evade the fire.

而且它是有效的。安大略省查塔姆市位於烏鴉遷徙路線的下方，在遷徙途中，烏鴉會在該鎮肆虐。每一次試圖擺脫他們的嘗試都失敗了——包括用霰彈槍向他們射擊。烏鴉學會了如何飛得足夠高來躲避火災。

5. Ravens are smart enough to be paranoid

5。烏鴉聰明到可以設想。

A study released in early 2016 found that ravens possess something known as the Theory of Mind - that is, the ability to recognise mental states within themselves, and extrapolate that others have mental states, too, and that those mental states in others may differ from their own.

2016年初發布的一項研究發現，烏鴉擁有一種被稱為心理理論的東西——也就是說，它們能夠識別自己內心的心理狀態，並推斷其他人也有心理狀態，而其他人的心理狀態可能與自己的不同。

Ravens like to stash food for later, and had been observed doing so more cautiously when other ravens were around.

烏鴉喜歡把食物藏起來以備日後食用，當其他烏鴉出現時，人們觀察到它們會更為謹慎。

To test this idea, ravens were trained to use a peephole to watch a human hiding food in an adjoining room. Then they were put in the second room with the food, and observed in two conditions: with the peephole closed, and with the peephole open and a loudspeaker playing raven cries.

為了驗證這個想法，烏鴉被訓練使用一個窺視孔來觀察一個藏在隔壁房間裡的食物。然後把他們和食物放在第二個房間裡，在兩種情況下觀察他們:窺視孔是關閉的，窺視孔是打開的，揚聲器播放著烏鴉的叫聲。

They behaved just as if another raven was in line-of-sight.

他們的行為就像另一隻烏鴉在視線中。

This indicated, the researchers wrote in their paper, "that they can generalise from their own experience using the peephole as a pilferer and predict that audible competitors could potentially see their caches. Consequently, we argue that they represent 'seeing' in a way that cannot be reduced to the tracking of gaze cues."

這表明，研究人員在他們的論文中寫道，“他們可以從自己的經驗中總結出，把窺視孔當作小偷，並預測，聽覺競爭對手可能會看到他們的緩存。”因此，我們認為，它們以一種不能被簡化為追蹤凝視線索的方式來代表‘看見’。”