May 9, 2012 - "Santino," a male chimpanzee at Furuvik Zoo in Sweden, is devising increasingly complex attacks against zoo visitors.
Here, he postures, looking tough, in front of zoo visitors.
At first Santino was famous for throwing rocks and other projectiles at visitors who annoyed him. Now he has improved his technique.
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Here's where Santino has hidden his rock and projectile stashes.
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After a visitor group had left the compound area, researchers watched as Santino went inside and brought out this heap of hay and placed it near the visitor's section.
Then he stashed stones under the pile.
Santino playing with little Selma, the youngest chimp in the exhibit at Furuvik Zoo in Sweden.
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After observing the chimp for days, the scientists also suspect that Santino just also "finds it fun" to bug humans.
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Santino may not be fond of human visitors, but he loves playing and spending time with Selma, a young chimp also at Furuvik Zoo.
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