This picture taken on July 25, 2014 shows people cooling off in a waterpark in Suining, southwest China's Sichuan province. Meteorological departments issued an orange alert for high temperature as a heat wave embraces Sichuan province, with temperature of most area topped 37, local media reported. (Photo by AFP Photo)

Football Soccer, England vs Wales, EURO 2016, Group B, Stade Bollaert-Delelis, Lens, France on June 16, 2016. Soccer fan Laura Woods from England fixes her makeup near riot police near the Lens stadium before the England vs Wales game. (Photo by Wolfgang Rattay/Reuters)

Catholic pilgrim Matilde Madalena de Jesus crawls on a rocky trail carrying a bottle of water on her head during the annual pilgrimage of the dead (Romaria dos Finados), in the city of Juazeiro do Norte, Ceara state, in Brazil October 31, 2016. (Photo by Ueslei Marcelino/Reuters)

Young girls perform in front of the monument to Soviet state founder Vladimir Lenin during the City Day celebrations in Yekaterinburg, Russia on August 19, 2017. (Photo by Maxim Shemetov/Reuters)

Londoners enjoy a “Silent Night” as Big Ben falls silent, London, UK on August 21, 2017. ose Allerston from Clapham, London said “After a stressful day in the office, I couldn't think of anything better than going home and climbing into bed – but when I saw this bed opposite Big Ben I just couldn't resist getting in for a snuggle”. (Photo by Imagewise Ltd/Rex Features/Shutterstock)

Members of the China Disabled Peoples Performing Art Troupe perform “My Dream” at Jorge Eliecer Gaitan Theater in Bogota on August 30, 2017. China Disabled People's Performing Art Troupe Company composed of artists with some hearing, mental, motor, visual or speech disabilities, was founded in 1987 and is currently Honorary and Goodwill Ambassadors of Unesco for its great example of inclusion. (Photo by John Vizcaino/AFP Photo)

This image of a young bareback rider was taken in the village of Palenque de San Basilio, in Colombia’s Bolívar department. Founded by freed slaves in the 17th century, it became the first free town in the Americas, following a decree by the Spanish crown. Most of today’s inhabitants are direct descendants of those slaves and have preserved many of their customs, including their own language, Palenquero. (Photo by Sebastián Suki Beláustegui/The Guardian)

Behaviour: Mammals category. Giant Gathering by Tony Wu, USA. Dozens of sperm whales mingled noisily off Sri Lanka’s northeast coast, stacked as far down as Tony could see. This was a congregation of dozens of social units, like a gathering of the clans. Aggregations like this could be a critical part of the whales’ rich social lives but are rarely reported. Some two thirds of the population was wiped out before commercial whaling was banned in 1986. This kind of major gathering could be “a sign that populations are recovering”, says Tony. (Photo by Tony Wu/Wildlife Photographer of the Year 2017)