Children play football in Bujumbura, Burundi on March 19, 2015. (Photo by Carl de Souza/AFP Photo)

A woman sits as she gets a tattoo on her leg during the annual Panama City Ink Fest in Panama City August 16, 2015. (Photo by Carlos Jasso/Reuters)

A wounded Syrian girl looks on at a make shift hospital in the rebel-held area of Douma, east of the capital Damascus, following shelling and air raids by Syrian government forces on August 22, 2015. At least 20 civilians and wounded or trapped 200 in Douma, a monitoring group said, just six days after regime air strikes killed more than 100 people and sparked international condemnation of one of the bloodiest government attacks in Syria's war. (Photo by Abd Doumany/AFP Photo)

People protest at the Boston Free Speech Rally in Boston, USA on August 19. 2017. With the Boston Free Speech rally was closed to the media (despite the Boston Common being a public space), a lot of the media’s coverage centred on the tensions within the larger counter-protest. (Photo by Stephanie Keith/Reuters)

Eight-year-old Lactatia a.k.a. Nemis Quinn Mélançon Golden gets a makeover by Ginger Minj during RuPaul's DragCon NYC 2017 at The Jacob K. Javits Convention Center on September 9, 2017 in New York City. (Photo by Santiago Felipe/Getty Images)

A drunk student is sick on the street watched by a police officer following a night of heavy drinking during freshers week in United Kingdom on November 28, 2007. (Photo by Matthew Horwood/Alamy Stock Photo)

An H-2A rocket carrying Japan's fourth and final quasi-zenith satellite, the Michibiki No. 4, lifts off from the Tanegashima Space Center in Kagoshima Prefecture, southwestern Japan in this photo taken by Kyodo on October 10, 2017. (Photo by Reuters/Kyodo News)

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)