Jane Howorth from national charity the British Hen Welfare Trust holds Liberty the last ex-battery hen to be rehomed on December 29, 2011 in Chulmleigh, England. The rehoming of Liberty signifies the end of the small battery hen cage, which has been phased out and replaced by enriched cages in preparation of the European Union directive banning the smaller cages from January 1, 2012. (Photo by Matt Cardy/Getty Images)

Members of Germany's elite police unit, the Spezialeinsatzkommando, or SEK, demonstrate an abseil deployment from a helicopter during a media event on March 20, 2012 in Minden, Germany. The SEK is the special response team of Germany's state police force and typically deploys in high-risk situations, such as bank robberies, hostage takings and the arrest of armed and dangerous fugitives. (Photo by Thomas Starke/Getty Images)

Armed Karo herdsman just back from protecting their cattle herds come down to the river to wash decorative clay markings off their bodies at the end of the day in the Omo Valley, South West Ethiopia. Dus, Omo Valley, Ethiopia, January 2008. (Photo by Brent Stirton/Discovery Communications)

Space shuttle Discovery sits atop NASA's 747 Shuttle Carrier Aircraft (SCA) ready to transport it from Kennedy Space Center to the Washington D.C., on April 17, 2012 in Cape Canaveral, Florida. Following the retirement of the shuttle fleet, Discovery will fly to Washington for display at the Smithsonian's National Air and Space Museum. (Photo by Lofty Ambitions)

An overcrowded dinghy with migrants from different African countries is followed by members of the German NGO Jugend Rettet as they approach the Iuventa vessel during a rescue operation, off the Libyan coast in the Mediterranean Sea September 21, 2016. (Photo by Zohra Bensemra/Reuters)

Students at the Cuba's National Ballet School (ENB) watch a class from outside the classroom in Havana, Cuba, October 12, 2016. Catherine Conley, the first American full-time student at Cuba's prestigious National Ballet School, hopes to gain an edge back home by learning the powerful Cuban style with its dazzling turns and jumps. (Photo by Alexandre Meneghini/Reuters)

Undated handout issued by Take A View of Sunrise at Winnats Pass, Derbyshire, England which won the Visit Britian “You're invited” Award for the best image from an overseas entrant category in this year's Landscape Photographer of the Year Awards. (Photo by Sven Mueller/PA Wire)

Santa Jerry Julian of Colorado Springs, Colorado hides in the grass following a ride on the Polar Express during a field trip from the Charles W. Howard Santa Claus School in Midland, Michigan, U.S. October 28, 2016. (Photo by Christinne Muschi/Reuters)