Amur tiger Iris licks her 7 week-old cub during one of their first walks in an open-air cage at the Royev Ruchey zoo in Russia's Siberian city of Krasnoyarsk. Iris gave birth to three cubs in the beginning of August, according to zoo employees. The Amur tiger is an endangered species. (Ilya Naymushin/REUTERS)

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Ilya Naymushin/REUTERS

Amur tiger Iris licks her 7 week-old cub during one of their first walks in an open-air cage at the Royev Ruchey zoo in Russia's Siberian city of Krasnoyarsk. Iris gave birth to three cubs in the beginning of August, according to zoo employees. The Amur tiger is an endangered species.