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)

Mave Grace, 11, who had part of her arm chopped off by militiamen when they attacked the village of Tchee, stands with her sister Racahele-Ngabausi, aged two, in an Internally Displaced Camp in Bunia, Ituri province, eastern Democratic Republic of Congo, April 12, 2018. (Photo by Goran Tomasevic/Reuters)

Tropical acrobatics by Adrià López Baucells in Manaus, Brazil. An unidentified South American marsupial, although the characteristic black markings on its face indicate it may be a mouse opossum. These small creatures are nocturnal and feed on bugs, fruit and bird eggs. (Photo by Adrià López Baucells/2019 Royal Society of Biology Photography Competition)

A Brazil supporter kisses a replica of the world cup trophy before the Qatar 2022 World Cup quarter-final football match between Croatia and Brazil at Education City Stadium in Al-Rayyan, west of Doha, on December 9, 2022. (Photo by Adrian Dennis/AFP Photo)

Australian professional boxer Ebanie Bridges at the weigh-in ahead of their IBF World Bantamweight Title fight against Shannon O'Connell during the weigh in at Aspire, Leeds, United Kingdom on Friday, December 9, 2022. (Photo by Tim Goode/PA Wire)

A reveller wearing a bearskin costume poses during the Bearskin Parade in Comanesti, Romania, on December 30, 2022. More than two hundred “bears” and dozens of musicians, surrounded by police and tourists, took part in the end-of-the-year parade. Young men and women dressed in real bearskin and traditional costumes paraded to chase away the evil spirits of the coming year. In all regions of Romania similar events exist but it is in this historical region of Moldova that they are the most developed. Comanesti has become the centre, attracting more and more troupes of dancers every year. (Photo by Daniel Mihailescu/AFP Photo)