Olaf Niess catches swans on the river Alster near the town hall in Hamburg, Germany, 17 November 2015. The Alster swans are moving to their ice-free winter quarters on the Eppendorf Muehlenteich millpond until spring. (Photo by Bodo Marks/EPA)

Bjorn, aged 5, smiles as he poses with a Owl butterfly during an event to launch the Sensational Butterflies exhibition at the Natural History Museum in London, Britain March 23, 2016. The exhibition opens to the public on March 24 and runs until September 11. (Photo by Dylan Martinez/Reuters)

Swiss police officers stand beside of mock gates of the NEAT Gotthard Base Tunnel inside the event hall for the upcoming opening ceremony near the town of Erstfeld, Switzerland May 31, 2016. The celebrations of the opening of the Gotthard Base Tunnel will start on June 1, 2016. With a length of 57 km (35 miles) crossing the Alps, the Gotthard Base tunnel is the world's longest train tunnel. (Photo by Arnd Wiegmann/Reuters)

A racegoer uses the camera on her phone to check her hair on the opening day of the Grand National Festival at Aintree Racecourse on April 3, 2014 in Aintree, England. The three days of racing attracts thousands of racegoers and fans from across the world. The meeting culminates with millions of pounds being wagered on the runners taking part in Europe's richest jump race, the Grand National. (Photo by Christopher Furlong/Getty Images)

A pro-Russian rebel shows his t-shirt depicting Russian President Vladimir Putin at a checkpoint in the village of Chornukhyne near the town of Debaltseve, north-east from Donetsk, March 12, 2015. (Photo by Marko Djurica/Reuters)

Dancers Daisy Kerry (R) and Alice Rathbone pose as characters from The Nutcracker, for the annual Christmas event at Chatsworth House near Bakewell in Britain November 4, 2016. (Photo by Darren Staples/Reuters)

Jack, a Lurcher from Dogs Trust Salisbury, walks past a window display of models in a Dogs Trust shop window in Salisbury, as part of a campaign to discourage the impulse buying of dogs ahead of Valentine's Day, on February 10, 2014. (Photo by Matt Alexander/PA Wire)

People walk past debris on May 3, 2015 in Bhaktapur, Nepal. A major 7.8 earthquake hit Kathmandu mid-day on Saturday, and was followed by multiple aftershocks that triggered avalanches on Mt. Everest that buried mountain climbers in their base camps. (Photo by David Ramos/Getty Images)