Models wait backstage during the Ukrainian Fashion Week in Kiev, October 16, 2015. (Photo by Valentyn Ogirenko/Reuters)

In this September 10, 1977, file photo, from left, Hua Guofeng, Chinese Communist Party (CCP) chairman and Mao Zedong's immediate successor; Ye Jianying, CCP vice chairman and future ceremonial head of state; Deng Xiaoping, no formal titles at the time but soon to emerge as paramount leader during the reform era; Li Xiannian, CCP vice chairman and future president; Wang Dongxing, head of the leadership bodyguard unit who helped topple the Gang of Four, view the body of later Chinese leader Mao Zedong in Beijing. (Photo via AP Photo)

A woman, wearing a traditional Sevillana dress, performs as she asks for alms in downtown Malaga, Spain, April 28, 2016. (Photo by Jon Nazca/Reuters)

Rick Sorenson, owner of the Rio Ramaza Marina, wades in the Sacramento River after securing an old paddlewheel boat on his property as the river makes its way up the levee on Garden Highway in Sacramento, Calif., Monday, January 9, 2017. (Photo by Hector Amezcua/The Sacramento Bee via AP Photo)

Cottbus Aviation Museum specialists prepare a Soviet Tupolev 134 A passenger plane for dismantlement in Gruenz, Germany, 10 July 2017. The team is preparing the 29 ton plane for transport from a garden in Gruenz to the Aviation Museum in Cottbus. The plane' s owner acquired it in 1991 and transported it with nine tractors and numerous helpers to his vegetable garden where he planned to open a cafe. The plane, formerly used by the East German Stasi for anti- terror operations training, is 30 metres long. (Photo by Jens Büttner/Zentralbild/DPA)

A family poses for photos near a dinosaur exhibits along the Changi Jurassic Mile as it is light up for Christmas near Changi airport in Singapore on December 8, 2020. (Photo by Tim Chong/Reuters)

Japanese macaques, also known as snow monkeys, play as they soak in a hot spring in Jigokudani valley in Nagano Prefecture, northwest of Tokyo Saturday, March 6, 2021. (Photo by Kiichiro Sato/AP Photo)

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)