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)

A woman is helped out of the wrecked car of a train that derailed at the station of Pioltello Limito, on the outskirts of Milan, Italy, Thursday, January 25, 2018. Italian officials said that the commuter train derailed in northern Italy, killing some people, seriously injuring 10 and trapping others heading into Milan at the start of the work day. (Photo by AP Photo/Stringer)

Women dancing at the disco club Xenon in New York City, USA in 1978. Xenon was a popular disco in Manhattan in the late 1970s and early 1980s. It was the only nightclub popular enough to compete with Studio 54. (Photo by Waring Abbott/Getty Images)

Journalists practice social distancing outside a meeting to wrap up work on coronavirus economic aid legislation to prevent the spread of coronavirus disease (COVID-19) in Washington, U.S., March 21, 2020. (Photo by Mary F. Calvert/Reuters)

People take turns stomping the Christopher Columbus statue after it was toppled in front of the Minnesota State Capitol in St. Paul, Minn., on Wednesday, June 10, 2020. (Photo by Leila Navidi/Star Tribune via AP Photo)

Buddy the dog peers from a vehicle before the start of a movie at a drive in cinema in Snagov, Romania, Monday, June 1, 2020. Romania further loosened the measures imposed during a nationwide lockdown in order to limit the spread of the COVID-19 infections, with museums, open air restaurants, cinemas and beaches opening for public on Monday. (Photo by Andreea Alexandru/AP Photo)

Festival crowd enjoying the weather on Day 1 of Reading Festival on August 25, 2017 in Reading, England. (Photo by Dean Fardell/Barcroft Images)

A woman has her photo taken wearing tradtional clothing as a Tibetan Buddhist woman and her family walk the kora near the Jokhang Temple, a UNESCO heritage site, during a government organized visit for journalists on June 1, 2021 in Lhasa, Tibet Autonomous Region, China. (Photo by Kevin Frayer/Getty Images)