A newly born Mexican gray wolf cub, an endangered native species, is seen at its enclosure at the Museo del Desierto in Saltillo, Mexico, July 19, 2016. Though once held in high regard in Pre-Columbian Mexico, it is the most endangered gray wolf in North America, having been extirpated in the wild during the mid-1900s through a combination of hunting, trapping, poisoning and digging pups from dens. (Photo by Daniel Becerril/Reuters)

Giant panda Mei Xiang discovers a birthday cake meant for her cub Bei Bei (NP) who turns one at the Smithsonian National Zoo in Washington, DC on August 20, 2016. (Photo by Linda Davidson/The Washington Post)

Karis, an 8 week old lion cub, growls at a pumpkin as she explores a Halloween treat put in her enclosure by staff at Blair Drummond Safari Park near Stirling, Scotland, Tuesday, October 29, 2013. (Photo by Andrew Milligan/AP Photo/PA Wire)

National Geographic photographer Steve Winter has spent most of his adult life shooting wild cats. Photo: A 14-month-old cub, cooling off in a pond, is riveted by a deer that appeared near the shore. Tigers are powerful swimmers; they can easily cross rivers four to five miles wide and have been known to swim distances of up to 18 miles. (Photo by Steve Winter/National Geographic)

A one-month-old wolf cub ululate as zookeeper Luo Yong plays guitar at the Chongqing Yongchuan Safari Park on March 27, 2008 in Chongqing, China. Luo has worked as a keeper in the wolf zone of the park after he graduated university. Luo has developed a special way to communicate with the wolves by trying to imitate the noises they make. He also teaches wolf cubs to ululate and some wolves will howl along when he plays guitar. (Photo by China Photos/Getty Images)

“Cub”. In the colony of penguins in South Georgia. (Photo and caption by Ondrej Zaruba/National Geographic Traveler Photo Contest)

ATTENTION! All pictures are presented in high resolution. To see Hi-Res images – just TWICE click on any picture. In other words, click small picture – opens the BIG picture. Click BIG picture – opens VERY BIG picture.

The first red panda cub was born on May 30 in zoo Zlin. Zoologist Roman Vrzal holds a male of red panda. The Red panda is pictured in Zlin, Czech Republic, August 20, 2014. (Photo by Dalibor Gluck/CTK)

A 6-month old female giant panda cub, an offspring of Xing Xing, formerly known as Fu Wa and Liang Liang, formerly known as Feng Yi, plays at the Giant Panda Conservation Center at the National Zoo in Kuala Lumpur, Malaysia, Thursday, February 18, 2016. (Photo by Joshua Paul/AP Photo)