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Crows, ravens, magpies and jays belong to the corvid family, among the cleverest birds known. New Caledonian crows shape twigs and leaves into hooked tools, and wild crows in Seattle scolded a mask for years after researchers wearing it had trapped them.

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New Caledonian crows live on islands in the Pacific east of Australia. To pull grubs out of holes, they make stick tools and tear strips from the edges of pandanus leaves, whose natural barbs work as hooks. In 2002, researchers at the University of Oxford saw a captive crow called Betty bend a straight wire into a hook and use it to fish a small bucket of food out of a tube. The mask experiment took place in Seattle, where John Marzluff's team at the University of Washington wore a distinctive mask while trapping and ringing wild American crows. For years afterwards, crows scolded anyone wearing that mask, including birds that had never been caught and had learned the danger from others. Corvids lack the layered cortex that primates think with, but like other birds they pack their nerve cells two to four times as densely as mammals do.

Türkçe oku
Kargalar, kuzgunlar, saksağanlar ve alakargalar kargagiller ailesindendir; bilinen en zeki kuşlar arasında yer alırlar. Yeni Kaledonya kargaları dal ve yapraktan kancalı aletler yapar. Seattle'da ise kendilerini yakalayan araştırmacıların maskesini gören kargalar, yıllar sonra bile yaygarayı bastı.

Yeni Kaledonya kargaları, Avustralya'nın doğusunda, Pasifik Okyanusu'ndaki adalarda yaşar. Deliklere saklanan kurtçukları çıkarmak için dallardan çubuk aletler yapar, pandanus yapraklarının dikenli kenarlarından da şeritler koparır; bu dikenler kanca işi görür. Oxford Üniversitesi'nde 2002'de yapılan bir deneyde Betty adlı karga, düz bir teli bükerek kanca yaptı ve dar bir borunun dibindeki küçük yiyecek kovasını onunla çekip çıkardı. Kargaların insan yüzlerini unutmadığını gösteren deney ise Seattle'da yapıldı: Washington Üniversitesi'nden John Marzluff'un ekibi, yabani Amerikan kargalarını yakalayıp ayaklarına halka takarken hep aynı maskeyi taktı. Sonraki yıllarda o maskeyi kim taksa kargalar başına toplanıp gakladı; hiç yakalanmamış kargalar bile tehlikeyi ötekilerden öğrenmişti. Kargagillerin beyninde, primatların düşünmek için kullandığı katmanlı beyin kabuğu yoktur; ama öteki kuşlar gibi onların beyninde de sinir hücreleri memelilerdekinden iki ila dört kat daha sık dizilidir.

Sources and further reading

Background reading: Corvidae
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