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)

An exhausted Rohingya refugee woman touches the shore after crossing the Bangladesh-Myanmar border by boat through the Bay of Bengal, in Shah Porir Dwip, Bangladesh, September 11, 2017. (Photo by Danish Siddiqui/Reuters)

The Aurora Borealis (Northern Lights) lights up the sky near the village of Pallas (Muonio region) of Lapland, Finland September 8, 2017. (Photo by Alexander Kuznetsov/Reuters/All About Lapland)

A Muslim woman wearing a Hijab stands in the waters in the Mediterranean Sea as an Israeli stands nearby on the beach in Tel Aviv, Israel August 21, 2016. (Photo by Baz Ratner/Reuters)

Swimmers in fancy costume take part in the New Year's Day swim at Saundersfoot in Wales, Britain, January 1, 2017. (Photo by Rebecca Naden/Reuters)

Samba dancers outside Woolwich station celebrate the opening of the Elizabeth Line in London, England on May 23, 2022. Originally due to open in December 2018, the £18.8bn railway links Reading and Essex via central London. (Photo by Jill Mead/The Guardian)

Supporters of presidential candidate Gustavo Petro, with the Historical Pact coalition, celebrate after his candidate won a presidential runoff in Bogota, Colombia, Sunday, June 19, 2022. (Photo by Fernando Vergara/AP Photo)

Revellers make the most of Friday night in Soho, central London after the hottest day of the year recorded in the capital this year, June 17, 2022. (Photo by Marcin Nowak/Alamy Live News)