A jogger is seen running at Hampstead Heath with London in the background on June 1, 2021. Britain sees temperatures increasing for the second day in a row after the mercury hit 25C (77 Fahrenheit) for the warmest day of the year so far on Bank Holiday Monday. (Photo by Joshua Bratt/London News Pictures)

Coronavirus vaccinated audience members watch Saudi prominent singer Mohammed Abdu as he performs at the newly built Super Dome, in Jiddah, Saudi Arabia, late Thursday, July 8, 2021. The concert is organized by the Saudi General Entertainment Authority after the kingdom lifted coronavirus restrictions on events in May. (Photo by Amr Nabil/AP Photo)

A child is pictured with the face covered in blood during a religious procession to mark Ashura in Nabatieh, southern Lebanon on August 19, 2021. (Photo by Aziz Taher/Reuters)

Gemma Sadler models a fabulous Georgian costume, including a wig made from flowers and foliage created by Florist of the Year Helen James, during the staging day for the 2021 Harrogate Autumn Flower Show at Newby Hall, near Ripon, United Kingdom on Thursday, September 16, 2021. (Photo by Danny Lawson/PA Images via Getty Images)

A student walks past on the broken bridge hit by a river overflow following floods in Jaranih village, Central Hulu Sungai, South Kalimantan province, Indonesia on November 17, 2021. (Photo by Bayu Pratama S./Antara Foto via Reuters)

Diver Sven, still in disguise, cleans the aquarium glass after a Santa Claus visit to the fish at Sea Life Berlin on December 6, 2021. (Photo by Christoph Soeder/dpa)

People participate in the first day of Thingyan Water Festival in Naypyitaw, Myanmar on April 13, 2018. The annual water festival, known as Thingyan, features large groups of people congregating to celebrate the by splashing water and throwing powder at each other's faces as a symbol of cleansing and washing away the sins from the old year. It marks the start of the traditional New Year and is similarly celebrated in countries such as Myanmar, Thailand, Laos and Cambodia. (Photo by Hein Htet/EPA/EFE/Rex Features/Shutterstock)

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)