Bison along the Bitterroot Valley's Eastside Highway north of Stevensville, Montana, are covered in snow following a blizzard on November 23, 2010. (Photo by Perry Backus/The Missoulian)

Pоrn actresses take a break at the Venus erotic fair in Berlin, Germany, October 15, 2015. The event, which represents the erotic business in the German capital, is open till October 18, 2015. (Photo by Fabrizio Bensch/Reuters)

Crowds watch surfers as the first big swell of the year arrives in Nazaré, Portugal on October 28, 2015. (Photo by Pedro Miranda/Demotix/Corbis)

Olaf Niess catches swans on the river Alster near the town hall in Hamburg, Germany, 17 November 2015. The Alster swans are moving to their ice-free winter quarters on the Eppendorf Muehlenteich millpond until spring. (Photo by Bodo Marks/EPA)

The “EMIEW3” robot (R) demonstrates communicating with a visitor during a press preview in Tokyo on April 8, 2016. Japanese electronics giant Hitachi unveiled its humanoid customer service and guidance robot “EMIEW3” and “remote brain” robotics IT platform. (Photo by Toshifumi Kitamura/AFP Photo)

Carlos Melendez prepares to feed his pet squirrel “Colita” in downtown San Salvador January 29, 2015. (Photo by Jose Cabezas/Reuters)

A girl with Russian national flags painted on her cheeks takes part in celebrations marking the first anniversary of Russia's annexation of Crimea, in central Simferopol March 16, 2015. Russia marks one year anniversary of annexation of Ukraine's Crimea peninsula this week. (Photo by Maxim Shemetov/Reuters)

General view of Chilean Calbuco volcano from Puerto Montt, located at 1000 km southern Santiago de Chile, Chile, 22 April 2015. Due to the eruption of the volcano with a smoke column 20 km high, authorities declared a red alert and ordered the evacuation of around 1500 inhabitants of Ensenada, Alerce, Colonia Río Sur and Correntoso towns. (Photo by Alex Vidal Brecas/EPA)