Displaced Sunni people, who fled the violence in the city of Ramadi, arrive at the outskirts of Baghdad, April 17, 2015. Iraqi security forces fought Islamic State militants at the gates of the western city of Ramadi on Friday, and local authorities warned it was in danger of falling unless reinforcements arrived soon. (Photo by Reuters/Stringer)

A man is silhouetted in front of the Allianz-Arena as he walks his dogs at sunrise in Munich, southern Germany, Friday, April 10, 2015. (Photo by Peter Kneffel/AP Photo/DPA)

A visitor holds up her toy bunny to the aquarium glass in front of Aurora the Russian polar bear at the Sao Paulo Aquarium in Sao Paulo, Brazil, Thursday, April 16, 2015. (Photo by Andre Penner/AP Photo)

Women dance during the traditional Feria de Abril (April fair) in the Andalusian capital of Seville, southern Spain, April 21, 2015. The fair will run until April 26. (Photo by Marcelo del Pozo/Reuters)

A reveller walks through the streets in the early hours during traditional May Day celebrations in Oxford, Britain, May 1, 2015. (Photo by Dylan Martinez/Reuters)

A colony of penguins gather with the Bark Europa in the background, on March 05, 2015 in South Georgia Island. An adventurer has documented his 5,000 miles journey aboard a 100-year-old ship, sailing from Argentina to Antarctica to Cape Town. (Photo by Andrew Orr/Barcroft Images)

Miss Utah Krissia Beatty competes in the swimsuit competition during the first night of preliminaries of Miss America at Boardwalk Hall in Atlantic City, New Jersey, September 8, 2015. (Photo by Mark Makela/Reuters)

A dog catches a frisbee during a dog frisbee competition in Moscow, September 13, 2015. Dogs and their owners took part in a variety of distance and accuracy tests during the competition to check their frisbee skills. (Photo by Sergei Karpukhin/Reuters)