Students pose for a pictures taken by their friends during spring break on the beach in the resort city of Cancun, Mexico, February 27, 2009. (Photo by Israel Leal/AP Photo)

Denver Broncos cheerleaders during the third quarter. The Denver Broncos played the Kansas City Chiefs at Sports Authority Field at Mile High in Denver, Colo. on September 14, 2014. (Photo by Aaron Ontiveroz/The Denver Post via Getty Images)

Participants wearing masks during a hazy day at the Beijing International Marathon in front of Tiananmen Square, in Beijing, October 19, 2014. (Photo by Reuters/Stringer)

White lioness Azira lies in the cage with her three white cubs, on February 4, 2014. Zoo owner Andrzej Pabich says white lions often have defects that prevent giving birth, or the mother rejects her cubs, but Azira has been patiently feeding and caring for her little ones. (Photo by Czarek Sokolowski/Associated Press)

Injured horses huddle together in Oklahoma City on Monday. (Photo by Chris Landsberger/The Oklahoman)

This handout photograph released by Taipei City Zoo on July 11, 2013 shows a newly-born panda cub of giant panda Yuan Yuan in an incubator at Taipei Zoo in Taipei. The public will have to wait three months to catch a glimpse of the first panda born in Taiwan, officials said after she was successfully delivered by parents who were gifted from China. (Photo by AFP Photo/Taipei City Zoo)

Tourists use a selfie stick on the Trocadero Square, with the Eiffel Tower in background, in Paris, Tuesday, January 6, 2015. Selfie sticks have become popular among tourists because you don't have to ask strangers to take your picture, and you can capture a wide view in a selfie without showing your arm. But some people find selfie sticks obnoxious, arguing that they detract from the travel experience. (Photo by Remy de la Mauviniere/AP Photo)