A man reacts to being warned by a British Transport Police officer for not wearing a face mask at King's Cross underground station, London, England on October 8, 2020. (Photo by Jonathan Brady/PA Images via Getty Images)

A Chicago Police Officer runs toward gunfire as looters break into downtown stores in the early hours of the morning on August 10, 2020. (Photo by RMV/Rex Features/Shutterstock)

A man wearing a protective face mask takes a photo near an art exhibition at a shopping mall, amid the coronavirus disease (COVID-19) outbreak in Jakarta, Indonesia, March 15, 2021. (Photo by Ajeng Dinar Ulfiana/Reuters)

Giant pandas are playing and foraging inside the Shenshuping base of China Conservation and Research Center for the Giant Panda in Wolong National Nature Reserve on November 3, 2021 in Aba Tibetan and Qiang Autonomous Prefecture, Sichuan Province of China. (Photo by An Yuan/China News Service via Getty Images)

Medic James E. Callahan of Pittsfield, Mass., gives mouth-to-mouth resuscitation to a dying soldier in war zone D, about 50 miles northeast of Saigon, June 17, 1967. Thirty-one men of the 1st Infantry Division were reported killed in the guerrilla ambush, with more than 100 wounded. (Photo by Henri Huet/AP Photo)

A classic American car is wrapped in plastic to prevent sea salt from corroding it in Havana, Cuba, Tuesday, March 2, 2021. Vintage cars in Cuba are part of daily life with most classic cars being used as taxis and to transport tourists. (Photo by Ramon Espinosa/AP Photo)

Tourists enjoy blooming cherry blossoms at China Pharmaceutical University on March 22, 2021 in Nanjing, Jiangsu Province of China. (Photo by Yang Bo/China News Service via Getty Images)

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)