People pose near a new Banksy artwork in Rothesay Avenue, Nottingham, Britain on October 17, 2020. (Photo by Carl Recine/Reuters)

People search for shells on a beach in Sittwe, Rakhine State, Myanmar, 17 September 2020. International Coastal Cleanup Day is observed annually on the third Saturday of September and will occur on 19 September this year. (Photo by Nyunt Win/EPA/EFE/Rex Features/Shutterstock)

A boy attempts to keep a candle lit in a flooded cemetery following Typhoon Molave, in Masantol, Pampanga, Philippines, October 27, 2020. (Photo by Eloisa Lopez/Reuters)

Supporters of US President Donald J. Trump gather for a rally in Freedom Plaza to protest Congress's upcoming certification of Joe Biden as the next president in Washington, DC, USA, 05 January 2021. Various groups of Trump supporters announced rallies on 06 January 2021 as Congress meets to certify the results of the 2020 US Presidential election. (Photo by Shawn Thew/EPA/EFE)

A parakeets lands on a woman's head at St James' Park in London, United Kingdom on February 9, 2021. London has been experiencing snow as the Storm Darcy hits the city. (Photo by Brett Cove/SOPA Images/Sipa USA)

A woman wearing a traditional costume attends the celebrations marking the National Flag Day and the Day of Kyrgyz national “Ak-kalpak” hat at the central Ala-Too Square in Bishkek on March 4, 2021. (Photo by Vyacheslav Oseledko/AFP 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)

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)