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60-SECOND SCIENCE, These Hawks Have Figured Out How to See the Bat in the Swarm

These Hawks Have Figured Out How to See the Bat in the Swarm

Birds of a feather flock together. And so do bats and fishes and any little critter hoping that getting lost in the crowd will keep them off the evening menu. But predators gotta eat. So they, in turn, have come up with clever ways to cut through the visual clutter of a churning mass of panicked prey to hone in on their target.

For hawks who forage in massive swarms of bats, the trick, it seems, is to just dive in and grab whatever hapless flier happens to share your trajectory. That's according to a study in the journal Nature Communications.

Graham Taylor: Intercepting even a single maneuvering target is a challenging task in itself.

Hopkin: Graham Taylor is a professor of mathematical biology at the University of Oxford. He got to wondering how predators like hawks and falcons manage to isolate and intercept a moving target when it's part of a flock or a swarm…a dense aggregation that seems like it would offer optimal protection for the prey.

Taylor: For one thing it can reduce your individual risk of coming under attack in the first place. And it might also make it harder for a predator to catch you if it initiates an attack at all.

Hopkin: That's thanks to the so-called “confusion effect.”

Taylor: Which is the idea that the presence of multiple similar targets makes it harder for a predator to single out and track any one individual.

Hopkin: But are swarms as confusing to a hawk as they might seem to you or me? To find out, Taylor teamed up with Laura Kloepper, a bat biologist at Saint Mary's College in Indiana, and headed to New Mexico.

Taylor: It's a very remote location in the Chihuahuan desert where there's a bat cave from which every evening close on a million Mexican free-tailed bats emerge. And waiting for the bats as they emerge in this huge stream that pours out of the cave are a number of Swainson's hawks, which plunge into the swarm and try and grab bats from it.

Hopkin: So Taylor and his team positioned video cameras strategically around the cave. And that found that…from the bat's point of view…swarming did, indeed, reduce a given individual's risk of being nabbed.

Taylor: But what we also found was that the hawks were no less successful at catching bats that were flying in the swarm than they were at catching lone bats. What that suggests then is that the hawks are not suffering from any kind of confusion effect.

Hopkin: But how do the hawks avoid getting visually disoriented when they're trying to snag a single bat from a sea of erratically flapping wings? To find out, the researchers compared the trajectories of both predator and prey. And they saw that attacking a swarm requires a different strategy than stalking an isolated individual.

Taylor: If you analyze the way in which a hawk chases after a single target, it really closely follows the twists and turns that the target makes as it tries to evade the hawk.

Hopkin: But not so when you're going for the swarm.

Taylor: Instead, the best model of the data was one that said that the hawks simply turned on a constant radius into the swarm, or perhaps more generally were targeting a fixed point in the swarm.

Hopkin: While steering toward this fixed point, the hawk can then reach out with its talons and scoop up any bat that's flying along the same path. And because they share the same trajectory, the bat will look to the hawk like it's not moving at all.

Taylor: The part of the swarm that the hawk is headed for is gonna appear effectively stationary compared to the movement of the rest of the swarm. So this provides a mechanism whereby it's possible for the bird plunging into the swarm to be able to identify which bit it's gonna hit, but then also to be able to single out a target within that without having to suffer from the confusion effect.

Hopkin: Taylor says the same should hold true for other predators that hunt prey in large flocks or shoals or murmurations. But for now we can safely say that, for Swainson's hawks, the chaos of the swarm doesn't seem to make their heads spin…even though it's totally batty.

For Scientific American's 60-Second Science, I'm Karen Hopkin.

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These Hawks Have Figured Out How to See the Bat in the Swarm Bu|şahinler||||nasıl||||Yarasa||| |ハクトウワシ|||||||||||群れ |||||||||pipistrello||| Diese Falken haben herausgefunden, wie sie die Fledermaus im Schwarm sehen können Estos halcones han descubierto cómo ver al murciélago en el enjambre Ces faucons ont compris comment voir la chauve-souris dans l'essaim Questi falchi hanno capito come vedere il pipistrello nello sciame 群れの中のコウモリを見る方法を見つけたタカたち 이 매들은 박쥐 떼를 보는 방법을 알아냈습니다. Šie vanagai sugalvojo, kaip pamatyti šikšnosparnį būryje Te jastrzębie odkryły, jak dostrzec nietoperza w roju Estes falcões descobriram como ver o morcego no meio do enxame Эти ястребы поняли, как увидеть летучую мышь в стае Bu Şahinler Sürüdeki Yarasayı Nasıl Göreceklerini Bulmuşlar Ці яструби навчилися бачити кажанів у рої 这些鹰已经找到了如何看到蝙蝠群中的蝙蝠 這些鷹已經找到瞭如何看到蝙蝠群中的蝙蝠

Birds of a feather flock together. |||Tüy|sürü halinde toplanır| |||stessa piuma|si radunano| Oiseaux d'une plume volent ensemble. 羽のような鳥が群がります。 物以类聚,人以群分。 And so do bats and fishes and any little critter hoping that getting lost in the crowd will keep them off the evening menu. ve|||yarasalar||||||hayvan||||||||||||||akşam menüsü |||i pipistrelli||||||creatura|||||||||||||| |||コウモリ||魚||||小さな生き物|||||||||||||| Il en va de même pour les chauves-souris, les poissons et toutes les petites bestioles en espérant que se perdre dans la foule les éloignera du menu du soir. そして、コウモリや魚、そして群衆の中で迷子になることを望んでいる小さな生き物もそうです. 蝙蝠、鱼和其他小动物也是如此,它们希望在人群中迷失方向后,就不会被列入晚上的菜单。 But predators gotta eat. |Ama yırtıcılar yemek zorunda.|yemeli| しかし、捕食者は食べなければなりません。 但捕食者总得吃东西。 So they, in turn, have come up with clever ways to cut through the visual clutter of a churning mass of panicked prey to hone in on their target. |||||||||||||||görsel karmaşa|||çalkalanan|||panik içindeki|av ||odaklanmak|||| ||||||||||||||||||in movimento|||||||||| ||||||||||||||||||渦巻く|||||||||| Alors, à leur tour, ils ont trouvé des moyens astucieux de couper à travers le fouillis visuel d'une masse agitée de proies paniquées pour se concentrer sur leur cible. そこで彼らは、パニックに陥った獲物の群れの視覚的な乱雑さを切り抜けて、ターゲットに焦点を合わせる巧妙な方法を考え出しました。 因此,它们反过来也想出了巧妙的办法,从惊慌失措的猎物群中穿过视觉杂波,锁定目标。

For hawks who forage in massive swarms of bats, the trick, it seems, is to just dive in and grab whatever hapless flier happens to share your trajectory. |||yiyecek aramak||devasa|sürüler halinde||yarasa||numara||||||dalmak|||||şanssız uçan|uçan hayvan|||||uçuş yolu |||餌を探す|||群れ|||||||||||||||運の悪い|||||| Pour les faucons qui se nourrissent d'énormes essaims de chauves-souris, l'astuce, semble-t-il, consiste simplement à plonger et à attraper le malheureux voleur qui partage votre trajectoire. コウモリの大群で餌を探すタカにとっての秘訣は、たまたま軌道を共有する不運な飛行者が何であれ、飛び込んでつかむことのようです。 对于在成群蝙蝠中觅食的鹰来说,窍门似乎就是俯冲进去,抓住与你轨迹相同的无助的飞行物。 That's according to a study in the journal Nature Communications. |||||||||İletişim C'est selon une étude publiée dans la revue Nature Communications. 这是根据《自然通讯》杂志上的一项研究得出的结论。

**Graham Taylor:** Intercepting even a single maneuvering target is a challenging task in itself. Graham Taylor|Graham Taylor|Engellemek||||manevra yapan||||zorlu||| ||||||機動する||||||| Graham Taylor : Intercepter ne serait-ce qu'une seule cible en manœuvre est une tâche difficile en soi. 格拉汉姆-泰勒:拦截哪怕是一个机动目标本身就是一项极具挑战性的任务。

**Hopkin:** Graham Taylor is a professor of mathematical biology at the University of Oxford. Hopkin||||||||||||| |グラハム|||||||||||| He got to wondering how predators like hawks and falcons manage to isolate and intercept a moving target when it's part of a flock or a swarm…a dense aggregation that seems like it would offer optimal protection for the prey. |||||||||şahinler ve doğanlar|||izole etmek||yakalamak|||||||||sürü|||sürü|||yoğun topluluk||||||||||| |||||||||ハヤブサ|||||捕らえる|||||||||||||||集団||||||||||| Il en est venu à se demander comment les prédateurs comme les faucons et les faucons parviennent à isoler et à intercepter une cible en mouvement lorsqu'elle fait partie d'un troupeau ou d'un essaim… une agrégation dense qui semble offrir une protection optimale pour la proie. 彼は、タカやハヤブサのような捕食者が、移動するターゲットが群れや群れの一部であるときに、どのように隔離して傍受できるのか疑問に思うようになりました...獲物に最適な保護を提供するように見える高密度の集合体. 他开始思考,当鹰和猎鹰等捕食者是鸟群或鸟群的一部分时,它们是如何孤立并拦截移动目标的......这种密集的聚集似乎能为猎物提供最佳保护。

**Taylor:** For one thing it can reduce your individual risk of coming under attack in the first place. ||||||azaltmak||||||||||| Taylor : D'une part, cela peut réduire votre risque individuel d'être attaqué en premier lieu. Taylor: まず第一に、個人が攻撃を受けるリスクを減らすことができます。 泰勒首先,它可以降低个人遭受攻击的风险。 And it might also make it harder for a predator to catch you if it initiates an attack at all. |||||||||yırtıcı hayvan||||||başlatırsa|||| |||||||||||||||攻撃を開始する|||| Et cela pourrait également rendre plus difficile pour un prédateur de vous attraper s'il lance une attaque. また、捕食者が攻撃を開始した場合、捕食者があなたを捕まえるのが難しくなる可能性もあります. 而且,如果捕食者发起攻击,它也可能更难抓住你。

**Hopkin:** That's thanks to the so-called “confusion effect.” |||||||kafa karışıklığı etkisi| ||||||いわゆる|| Hopkin : C'est grâce au soi-disant « effet de confusion ». 霍普金这要归功于所谓的 "混淆效应"。

**Taylor:** Which is the idea that the presence of multiple similar targets makes it harder for a predator to single out and track any one individual. |||||||varlığı|||||||||||||||takip etmek||| ||||||||||||||||||||||追跡する||| Taylor: これは、似たような標的が複数存在すると、捕食者が特定の個体を特定して追跡するのが難しくなるという考えです。 泰勒就是说,多个相似目标的存在,会让捕食者更难找出并追踪任何一个个体。

**Hopkin:** But are swarms as confusing to a hawk as they might seem to you or me? |||||kafa karıştırıcı||||||||||| ||||||||鷹|||||||| ホプキン: しかし、群れは、あなたや私に見えるかもしれないのと同じくらいタカを混乱させますか? 霍普金但是,对鹰来说,蜂群就像你我看到的那样令人困惑吗? To find out, Taylor teamed up with Laura Kloepper, a bat biologist at Saint Mary's College in Indiana, and headed to New Mexico. |||||||Laura Kloepper|Kloepper||||||Saint Mary's Koleji||||||||Yeni Meksika Pour le savoir, Taylor s'est associé à Laura Kloepper, biologiste des chauves-souris au Saint Mary's College dans l'Indiana, et s'est rendu au Nouveau-Mexique. それを調べるため、テイラーはインディアナ州セント・メアリーズ・カレッジのコウモリ生物学者であるローラ・クレッパーとチームを組み、ニューメキシコに向かいました。 为了找出答案,泰勒与印第安纳州圣玛丽学院的蝙蝠生物学家劳拉-克罗伊珀(Laura Kloepper)合作,前往新墨西哥州。

**Taylor:** It's a very remote location in the Chihuahuan desert where there's a bat cave from which every evening close on a million Mexican free-tailed bats emerge. ||||||||Chihuahua||||||yarasa mağarası|||||||||Meksika'ya özgü||kuyruklu|| ||||||||チワワ砂漠||||||||||||||||||| Taylor : C'est un endroit très isolé dans le désert de Chihuahuan où il y a une grotte aux chauves-souris d'où émergent chaque soir près d'un million de chauves-souris mexicaines à queue libre. テイラー: チワワ砂漠の非常に人里離れた場所で、コウモリの洞窟があり、そこから毎晩 100 万匹のオオコウモリが現れます。 泰勒:那是奇瓦瓦沙漠中一个非常偏僻的地方,那里有一个蝙蝠洞,每天晚上都会有近百万只墨西哥自由尾蝠从洞里出来。 And waiting for the bats as they emerge in this huge stream that pours out of the cave are a number of Swainson's hawks, which plunge into the swarm and try and grab bats from it. |||||||||||||||||||||||||dalmak|||sürü||||||| |||||||||||||流れ出す|||||||||スワインソン|||突入する|||||||||| Et attendant que les chauves-souris émergent dans cet immense ruisseau qui se déverse de la grotte, un certain nombre de faucons de Swainson plongent dans l'essaim et tentent d'en attraper des chauves-souris. 当蝙蝠从洞穴中涌出的巨大溪流中出现时,等待它们的是几只斯温森氏鹰,它们跳进蝙蝠群中,试图从里面抓住蝙蝠。

**Hopkin:** So Taylor and his team positioned video cameras strategically around the cave. ||||||配置した|||戦略的に||| 霍普金泰勒和他的团队在洞穴周围战略性地安置了摄像机 And that found that…from the bat's point of view…swarming did, indeed, reduce a given individual's risk of being nabbed. ||||||yarasanın||||sürü halinde hareket etmek||||||bireyin||||yakalanmak ||||||||||群れを作る||||||||||捕まる Et cela a révélé que… du point de vue de la chauve-souris… l'essaimage réduisait effectivement le risque d'être attrapé par un individu donné. 结果发现......从蝙蝠的角度来看......蜂拥而至确实降低了特定个体被捕获的风险。

**Taylor:** But what we also found was that the hawks were no less successful at catching bats that were flying in the swarm than they were at catching lone bats. ||||||||||||||||||||||||||||yalnız başına| Taylor : Mais ce que nous avons également découvert, c'est que les faucons ne réussissaient pas moins à attraper les chauves-souris qui volaient dans l'essaim qu'à attraper les chauves-souris solitaires. 泰勒:但我们还发现,老鹰捕捉成群飞舞的蝙蝠的成功率并不亚于捕捉单独的蝙蝠。 What that suggests then is that the hawks are not suffering from any kind of confusion effect. Ce que cela suggère alors, c'est que les faucons ne souffrent d'aucun effet de confusion.

**Hopkin:** But how do the hawks avoid getting visually disoriented when they're trying to snag a single bat from a sea of erratically flapping wings? |||||||||görsel olarak şaşkın|||||kapmak||||||||düzensizce|çırpınan kanatlar| |||||||||方向感覚を失う|||||||||||||不規則に|羽ばたく| Hopkin : Mais comment les faucons évitent-ils d'être visuellement désorientés lorsqu'ils essaient d'attraper une seule chauve-souris dans une mer d'ailes qui battent de façon erratique ? To find out, the researchers compared the trajectories of both predator and prey. |||||||軌道||||| Pour le savoir, les chercheurs ont comparé les trajectoires des prédateurs et des proies. And they saw that attacking a swarm requires a different strategy than stalking an isolated individual. ||||saldırmanın||sürü||||||izini sürmek||| ||||||||||||個体を追跡する||| Et ils ont vu qu'attaquer un essaim nécessite une stratégie différente de celle de traquer un individu isolé.

**Taylor:** If you analyze the way in which a hawk chases after a single target, it really closely follows the twists and turns that the target makes as it tries to evade the hawk. ||||||||||kovalar||||||||||||||||||||||| |||||||||||||||||||||||||||||||逃れる|| Taylor : Si vous analysez la manière dont un faucon poursuit une seule cible, il suit de très près les rebondissements que la cible fait lorsqu'elle tente d'échapper au faucon.

**Hopkin:** But not so when you're going for the swarm. Hopkin : Mais ce n'est pas le cas quand vous visez l'essaim.

**Taylor:** Instead, the best model of the data was one that said that the hawks simply turned on a constant radius into the swarm, or perhaps more generally were targeting a fixed point in the swarm. ||||||||||||||||||||yarıçap|||||||||hedef alma|||||| ||||||||||||||||||||半径1|||||||より一般的に|||||||| Taylor : Au lieu de cela, le meilleur modèle de données était celui qui disait que les faucons tournaient simplement sur un rayon constant dans l'essaim, ou peut-être plus généralement ciblaient un point fixe dans l'essaim.

**Hopkin:** While steering toward this fixed point, the hawk can then reach out with its talons and scoop up any bat that's flying along the same path. ||yönelme|||||||||||||pençeler||kavramak||||||||| ||操縦し|||||||||||||爪||||||||||| Hopkin : En se dirigeant vers ce point fixe, le faucon peut alors tendre la main avec ses serres et ramasser toute chauve-souris qui vole le long du même chemin. And because they share the same trajectory, the bat will look to the hawk like it's not moving at all. ||||||||yarasa|||||||||||

**Taylor:** The part of the swarm that the hawk is headed for is gonna appear effectively stationary compared to the movement of the rest of the swarm. |||||||||||||olacak|||sabit duran|||||||||| ||||||||||||||||静止している|||||||||| Taylor : La partie de l'essaim vers laquelle se dirige le faucon apparaîtra effectivement stationnaire par rapport au mouvement du reste de l'essaim. So this provides a mechanism whereby it's possible for the bird plunging into the swarm to be able to identify which bit it's gonna hit, but then also to be able to single out a target within that without having to suffer from the confusion effect. ||||mekanizma sağlar|||||||dalış yapan|||||||||||||||||||||||||||||||||| |||||||||||突入する|||||||||||||||||||||一つ||||||||||||| Cela fournit donc un mécanisme par lequel il est possible pour l'oiseau plongeant dans l'essaim d'être en mesure d'identifier quel morceau il va toucher, mais aussi d'être capable d'isoler une cible à l'intérieur sans avoir à souffrir de l'effet de confusion.

**Hopkin:** Taylor says the same should hold true for other predators that hunt prey in large flocks or shoals or murmurations. ||||||||||||||||||sürüler halinde||sürü hareketleri ||||||||||||||||||群れ|| Hopkin: Taylor dit que la même chose devrait être vraie pour les autres prédateurs qui chassent des proies dans de grands troupeaux ou des bancs ou des murmures. But for now we can safely say that, for Swainson's hawks, the chaos of the swarm doesn't seem to make their heads spin…even though it's totally batty. ||||||||||||||||||||||dönmek|||||çılgınca |||||||||||||||||||||||||||おかしい Mais pour l'instant, nous pouvons affirmer que, pour les faucons de Swainson, le chaos de l'essaim ne semble pas leur faire tourner la tête… même s'il est totalement fou. しかし今のところ、スウェインソンのタカにとって、群れの混沌は彼らの頭を回転させないように見える.

For Scientific American's 60-Second Science, I'm Karen Hopkin. ||||||Karen Hopkin|