A baby elephant eats in a swamp in Amboseli national park, Kenya, March 19, 2017. (Photo by Goran Tomasevic/Reuters)

A rabbit fails to jump over an obstacle during a rabbit track and field competition on the sidelines of a hunting exhibition in Kromeriz, about 60 km east of Prague, on April 1, 2017. Circa 100 rabbits took part in the competition, including disciplines as long jump, high jump and running on a flat track. (Photo by Radek Mica/AFP Photo)

A baby Black-crowned Night Heron squawks in its incubator while being cared for at City Wildlife rescue and rehabilitation center in Washington, DC on May 31, 2017. The heron is one of several that have been brought to CW by the staff at The National Zoo over the past few years. (Photo Linda Davidson/The Washington Post)

This handout picture taken on December 13, 2016 and released on December 14, 2016 by the Tiergarten Schoenbrunn zoo in Vienna, Austria, shows a baby sloth eating some salad as it hangs on it's mother's belly in their enclosure. The baby was born already on November 18, 2016, but according to the zoo it could be picured for the first time only now as it usually hides in it's mother's soft coat. (Photo by Daniel Zupanc/AFP Photo)

October winner. “A burst of the aurora borealis over Kirkjufell, taken in September 2016. This shot has been a holy grail for me and was finally captured after many trips”. MICK RYAN, JUDGE: Iceland is a hotspot for aurora photography and this composition of the symmetric, free-standing Kirkjufell and the trident waterfall is much-sought after. If you can time your visit when the aurora “kp” index is high and know the settings for nighttime aurora images, you may end up with a beautiful photograph like this. (Photo by DВ/The Guardian)

In this Tuesday, December 20, 2016 photo, Mohammad Ramzan, right, reacts while talking to The Associated Press with his young bride Saima in Jampur, Pakistan. Saima was given as a bride to the older man by her father so he could marry the groom’s sister, a practice of exchanging girls that is entrenched in conservative regions of Pakistan. It even has its own name in Urdu: Watta Satta, “give and take”. A mix of interests – family obligations, desire for sons, a wish to hand off a girl to a husband – can lead to a young teen in an a marriage she never sought. (Photo by K.M. Chaudhry/AP Photo)

Behaviour: Mammals category. Giant Gathering by Tony Wu, USA. Dozens of sperm whales mingled noisily off Sri Lanka’s northeast coast, stacked as far down as Tony could see. This was a congregation of dozens of social units, like a gathering of the clans. Aggregations like this could be a critical part of the whales’ rich social lives but are rarely reported. Some two thirds of the population was wiped out before commercial whaling was banned in 1986. This kind of major gathering could be “a sign that populations are recovering”, says Tony. (Photo by Tony Wu/Wildlife Photographer of the Year 2017)

A young Bengal tiger cub smuggled into the US and seized at the Mexico border is displayed for the media during Operation Jungle Book at the US Fish and Wildlife Service in Torrance, California on October 20, 2017. Operation Jungle Book, a law enforcement initiative led by the US Fish and Wildlife Service that targeted wildlife smuggling, resulting in federal criminal charges against defendants who allegedly participated in the illegal importation and/ or transportation of numerous animal species – including a tiger, monitor lizards, cobras, Asian “lucky” fish, exotic songbirds and several coral species. (Photo by Mark Ralston/AFP Photo)