Visitors watch as Grigory Broverman, a member of the Cryophile winter swimmers club, pours a bucket of cold water over his 6-year-old daughter Liza during a flash mob, part of a celebration of Polar Bear Day at the Royev Ruchey Zoo in a suburb of the Siberian city of Krasnoyarsk, Russia, November 29, 2015. The air temperature was around minus 5 degrees Celsius. (Photo by Ilya Naymushin/Reuters)

“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)

A close up of a caracal lynx's face looking into a camera on January 2014 in Western Cape, South Africa. (Photo by Dale Morris/Barcroft Media)

The pelican, named “Ndagabar”, which means pelican in the local Wolof language, begins visiting the neighborhood in the early hours of the day in Saint-Louis, Senegal on November 02, 2024. The pelican, which 62-year-old retired fisherman Madiop Gueye, has been keeping in front of his house for five years, has become the center of both the neighborhood and the region, attracting the attention of both local and foreign tourists. (Photo by Cem Ozdel/Anadolu via Getty Images)

A red deer looks as though it is yawning while it bellows at sunrise. The stag created a cloud of steamy breath as it was warmed by the first light of the sun in Richmond Park, London on October 28, 2025. (Photo by Cristian Vasile/Solent News & Photo Agency)

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)

A handout image released by the Taronga Zoo shows Veiled Chameleon hatchlings at Taronga Zoo in Sydney, Australia, 11 March 2015. Taronga has welcomed more than 20 baby chameleons, with the last of three clutches of eggs hatching this week. Veiled Chameleons, or Chamaeleo calyptratus, are native to Saudi Arabia and Yemen and can live up to five years. (Photo by EPA/Taronga Zoo)

A young tiger tries to get at poultry parts hidden in a pumpkin at Magdeburg Zoo, Germany on October 30, 2025. The zoo is celebrating Halloween from October 31, 2025 to November 1, 2025. In addition to the puppet theater, children's carousel and children's train, visitors can carve their own pumpkins, which are then distributed to the zoo animals and serve as food. (Photo by Klaus-Dietmar Gabbert/Avalon)