British holidaymaker Sean Chinn captures a crocodile on camera during a dive at the Jardines de la Reina marine park in Caribbean Sea, Cuba. (Photo by Sean Chinn/Caters News Agency)

Cambridge policemen, known as “Bulldogs”, lined up for the University Bulldogs Chase, dressed in morning coats and top hats, 7th March 1936. (Photo by H. Allen/Topical Press Agency/Getty Images)

A tamed hawk sits on a chair next to a participant during a traditional hunting contest in Almaty, Kazakhstan on December 1, 2018. (Photo by Pavel Mikheyev/Reuters)

In this Tuesday, February 5, 2019, photo, fire-eater performs during celebrations of the Lunar New Year in the Chinatown district of Manila, Philippines. This year is the Year of the Earth Pig in the Chinese Lunar calendar and is supposed to represent abundance, diligence and generosity. (Photo by Bullit Marquez/AP Photo)

Drag Queens set a Guinness World Record for the longest feather boa at 1.2 miles, along 42 St, in Times Square in New York, U.S., June 20, 2019. (Photo by Eduardo Munoz/Reuters)

An annual fire festival is held in Nachikatsuura, Wakayama Prefecture, western Japan, on July 14, 2019. (Photo by Kyodo News via 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)

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)