Smithsonian National Zoo biologist Leigh Pitsko releases a male lion cub for its swim test in the zoo habitat moat, in Washington May 6, 2014. Four, unnamed ten-week old lion cubs were tested today for their ability to swim and remove themselves from their zoo habitat moat. (Photo by Gary Cameron/Reuters)

Karis, an eleven week old lion cub, plays in fallen leaves brushed up by keepers in her enclosure at Blair Drummond Safari Park, near Stirling, Scotland, on November 20, 2013. (Photo by Andrew Milligan/PA Wire)

Hugo Belleri (L), a three-year-old boy and the youngest Gilles of Binche, takes part in the parade of Young Gilles of Binche during the carnival event in Binche February 17, 2015. The Binche carnival, a UNESCO World Heritage event, is the biggest and the liveliest annual event in Belgium. Up to 1,000 Gilles parade in the city centre of Binche, wearing a red, yellow and black medieval costume hung with bells and decorated with fluffy lace at the neck, wrists and ankles. (Photo by Yves Herman/Reuters)

People carry drinks at 80s Bar in Damascus, Syria, March 11, 2016. In Damascus's Old City, just a mile from the battered frontline between government and rebel-held territory, young Syrians smoke, drink beer or soft drinks, and talk about anything but the war. The revival of activity in this once-vibrant quarter is part of efforts to project an air of normality in the Syrian capital, even as the five-year-old war that has killed more than 250,000 people and created 5 million refugees continues to rage nearby. (Photo by Omar Sanadiki/Reuters)

Goyo, an eight-month-old mini pig, plays with a dog in Mexico City, December 21, 2015. Mini pigs can grow to about 30 kg (66.1 lbs) in weight and about 35 cm (1.1 ft) in height, according to the company Mini Pigs Mexico. The company says that the mini pigs' popularity as pets is growing and around 300 are sold every year in Mexico, with prices ranging from $350 to $1,600. (Photo by Edgard Garrido/Reuters)

Mariam, a 9-year-old girl, carries her brother as she stands with other children at an underground ancient cemetery in Jabal al-Zawiya in the southern countryside of Idlib November 26, 2014. Residents are using ancient caves and cemeteries as underground shelters to hide in during shelling from forces loyal to President Bashar al-Assad. Picture taken November 26, 2014. (Photo by Khalil Ashawi/Reuters)

A breeder poses with fruits and specially made high-fibre bread, for 36-year-old giant panda Jia Jia, at the Hong Kong Ocean Park, China June 30, 2015. Jia Jia, the oldest giant panda living in captivity, is set to challenge the world record for the animals' longevity, with her age said to put her on par with a human centenarian. (Photo by Tyrone Siu/Reuters)

A ten-week-old North China leopard (Panthera pardus japonensis) is handled during a routine health check in the Zoo of Debrecen, northeastern Hungary, 30 January 2024. The female cub, which was born on 21 November 2023, belongs to a leopard subspecies that is endemic to the forest habitats of Northern China. (Photo by Zsolt Czegledi/EPA/EFE)