A mother bear takes a dip in the water to cool off in the warm summer sun but refuses to leave her three youngsters behind – so they climb aboard her back. (Photo by Jon Langeland/Solent News & Photo Agency)

Two Herens cows lock horns during the qualification round of the annual “Battle of the Queens” cow fight finals in Aproz, in the western Alpine canton of Valais May 5, 2013. Each year when taken to the alpine pastures, the cows test their strength and fight for the herd's leadership. The competition continues until a new queen has forced all the other cows to retreat. (Photo by Valentin Flauraud/Reuters)

Kenichi Ito runs on his arms and legs on a race course on his way to setting the Guinness World Record fastest time for the 100-meter dash on all fours at Komazawa Olympic Park Stadium in Tokyo Thursday, November 14, 2013. The 30-year-old Japanese finished in 16.87 seconds Thursday, shaving more than half a second off his 2012 run of 17.47. (Photo by Shizuo Kambayashi/AP Photo)

Young female Ibex on the fork of Disteis (2,200 m), near the top of the Jof di Montasio (Friuli, Italy). (Photo by Stefano Zocca)

Kashir Mir, 34, poses for a photograph at his workplace, Juliet Wig Shop, in the London constituency of Brent Central, Britain, April 13, 2015. Mir, who was born in Pakistan, said: “I will vote but it's a secret. I also hope they can manage immigration better as I have been stopped and interviewed for hours returning from Pakistan. I'm an honest man, working here and paying my tax”. Brent, a northwest London neighbourhood that's home to Wembley football stadium, is among the most ethnically diverse areas in the United Kingdom. As the country approaches a closely fought election on May 7, Reuters photographer Eddie Keogh visited shopkeepers to get their views on the poll. (Photo by Eddie Keogh/Reuters)

In this February 19, 2017 photo, a couple dances during the “If you don't give me....then you lend me” Carnival street party on Ipanema beach, in Rio de Janeiro, Brazil. The typical view of Carnival in Brazil is anything goes, with no headdress too big, no outfit too small, no song too ribald, but this year some organizers of the world's best known party are drawing the line at lyrics that are sexist, homophobic or racist. (Photo by Silvia Izquierdo/AP Photo)

The possible surface of TRAPPIST-1f, one of seven newly discovered planets in the TRAPPIST-1 system that scientists using the Spitzer Space Telescope and ground based telescopes have discovered. (Photo by Reuters/NASA/JPL-Caltech)

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)