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)

A mahout guards the elephants during the annual Vrischikolsavam festival, which features a colourful procession of decorated elephants along with drum concerts, at a temple in Kochi, India, November 18, 2017. (Photo by Sivaram V/Reuters)

Filipino children play as they are doing caroling activities on the street near an airport, days before Christmas in Manila, Philippines, 20 December 2017. Filipinos celebrate the longest Christmas in the world which starts as early as September every year. (Photo by Francis R. Malasig/EPA/EFE)

Participants take part in the annual New Year' s Day Parade in central London, United Kingdom on January 1, 2018. Reports state that 8,000 performers representing the London boroughs and countries from across the globe are parading along the streets of London's West End on New Year’s Day. (Photo by Tolga Akmen/AFP Photo)

A boy plays with pelicans in Yoff, commune of Dakar, Senegal March 14, 2018. (Photo by Zohra Bensemra/Reuters)

Demonstrators argue in front of the Louisville Metro Hall on September 5, 2020 in Louisville, Kentucky. Ahead of the Kentucky Derby, demonstrators clashed over recent looting and destruction in the area and the death of Breonna Taylor, who was fatally shot by Louisville Metro police officers during a no-knock raid at her apartment on March 13, 2020. (Photo by Brandon Bell/Getty Images)

A child in colorful kimono walks at Tokyo's Asakusa district on the occasion of Shichigosan celebration Thursday, October 22, 2020. The festival celebrates children aged three, five and seven for their well-being. (Photo by Eugene Hoshiko/AP Photo)

A stag reacts as magpies and crows fuss over a resting stag as they feed on ticks from the fur of the deer herd roaming on the Ashton Court Estate, Bristol, in crisp and cold Autumnal weather on November 23, 2020. (Photo by Ben Birchall/PA Images via Getty Images)