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)

Riot police clash with demonstrators protesting against proposed pension reforms outside the Congress in Buenos Aires on December 18, 2017. Protesters angry at proposed pension and welfare reforms attacked police close to Argentina's congress building in Buenos Aires on Monday, the second protest in a week to turn violent. Activists lobbed stones, bottles and firecrackers at police as huge crowds demonstrated against pension reforms proposed by the center-right government of President Mauricio Macri. (Photo by Eitan Abramovich/AFP Photo)

Hostesses pose in front of a Suzuki Ignis car at the European Motor Show in Brussels, Belgium, January 13, 2017. (Photo by Francois Lenoir/Reuters)

An undated handout picture released on January 10, 2017 by the Issekinicho publishing house shows an inter- species sexual behaviour between a male Japanese macaque and female sika deer, in Yakushima Scientists revealed on January 10, 2017 the “highly unusual” behaviour of a male monkey filmed trying to have sеx with female deer in Japan – a rare case of inter- species nookie. (Photo by Editions Issekinicho/AFP Photo)

Migrant children run away from clashes with Mexican National Guards after their group crossed the Suchiate River on foot from Guatemala to Mexico, on the riverbank near Ciudad Hidalgo, Mexico, Monday, January 20, 2020. More than a thousand Central American migrants hoping to reach the United States marooned in Guatemala are walking en masse across a river leading to Mexico in an attempt to convince authorities there to allow them passage through the country. (Photo by Santiago Billy/AP Photo)

A municipality worker in a protective suit feeds street cats at Sultanahmet Square, as the spread of coronavirus disease (COVID-19) continues in Istanbul, Turkey, April 9, 2020. (Photo by Umit Bektas/Reuters)

People wear traditional Chinese outfits as they walk in Chinatown in Bangkok on February 11, 2021, ahead of the start of the Lunar New Year, which ushers in the Year of the Ox on February 12. (Photo by Lillian Suwanrumpha/AFP Photo)

Olga Fatkulina of the Russian Olympic Committee flops onto the infield after finishing her heat in the women's speedskating 1,000-meter finals at the 2022 Winter Olympics, Thursday, February 17, 2022, in Beijing. (Photo by Ashley Landis/AP Photo)