A participant takes part in donkey racing, during the 21st edition of annual Lamu Cultural Festival, in Lamu, Kenya, Saturday December 2, 2023. (Photo by AP Photo/Stringer)

Dogs and humans dressed in all manner of costume participate in the 32nd Annual Tompkins Square Halloween Dog Parade inside Tompkins Square Park on October 22, 2022 in New York City. (Photo by Andrew Schwartz/Splash News and Pictures)

Brazil's Kathellen in action with Australia's Alanna Kennedy during the Australia vs Brazil, Group C match at the FIFA Women's World Cup at Stade La Mosson Stadium on June 13th 2019 in Montpellier, France. (Photo by Eric Gaillard/Reuters)

This photo taken on February 26, 2019 shows an aerial view of a tea field in Zhangping in China's eastern Fujian province. (Photo by AFP Photo/China Stringer Network)

Darth Vader balloon above Clifton Suspension Bridge during the hot air balloons mass ascent at sunrise on the first day of the Bristol International Balloon Fiesta on August 8, 2019 in Bristol, England. The Bristol International Balloon Fiesta is Europe's largest annual meeting of hot air balloons, attracting over 130 hot air balloons from across the globe. (Photo by Finnbarr Webster/Getty Images)

In this August 26, 2019 photo, children of the Nambikwara Sarare tribe climb trees as they play in their indigenous reserve in the southwestern Amazon, near Conquista D'Oeste, in the Brazilian state of Mato Grosso. About 98% of all Brazil’s indigenous lands lie within the Amazon. (Photo by Andre Penner/AP Photo)

Pascal Martinot-Lagarde, of France, celebrates his bronze medal in the men's 110 meter hurdles final at the World Athletics Championships in Doha, Qatar, Wednesday, October 2, 2019. (Photo by Petr David Josek/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)