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 newly born albino red-necked wallaby joey eats as it is being carried by its mother in their enclosure at the zoo in Decin, Czech Republic, May 18, 2022. (Photo by David W. Cerny/Reuters)

Shooting star by Tony Wu, US/Japan. Winner, underwater. The electrifying reproductive dance of a giant sea star. As the surrounding water filled with sperm and eggs from spawning sea stars, Wu faced several challenges. Stuck in a small, enclosed bay with only a macro lens for photographing small subjects, he backed up to squeeze the undulating sea star into his field of view. The dancing posture of spawning sea stars rising and swaying may help release eggs and sperm, or may help sweep the eggs and sperm into the currents where they fertilise together in the water. Kinko Bay, Japan. (Photo by Tony Wu/Wildlife Photographer of the Year)

Monkeys climb on top of tourists during the Lopburi Monkey Festival on November 27, 2022 in Lop Buri, Thailand. Lopburi holds its annual Monkey Festival where local citizens and tourists gather to provide a banquet to the thousands of long-tailed macaques that live in central Lopburi. (Photo by Lauren DeCicca/Getty Images)

A black-winged stilt patrols a reservoir in Jezreel Valley in Israel early April 2023. Their eggs are a golden colour mottled with brown. (Photo by Itamar Procaccia/Solent News)

Tasmanian devils play on May 31, 2023 in Sydney, Australia. Creatures living at the zoo welcomed the arrival of winter with snow and an array of treats. Many of the zoo's species would naturally experience seasonal changes within their wild ranges. With the support of the SEA LIFE Sydney Aquarium's sub-Antarctic penguin team, snow is predicted to hit the Darling Harbour-based attraction on Wednesday morning. (Photo by Jenny Evans/Getty Images)

Muharrem Yilmaz, 78, takes his dog “Toprak” to a scooter and a swing ride everyday in Aydin, Turkiye on June 14, 2024. Yilmaz started taking his dog to long scooter rides after realising it likes to play with his grandkids' scooter. Then, he made a swing out of fruit boxes for the dog. Yilmaz adopted his dog Toprak two years ago when he found it in a restaurant garden as a lost puppy. (Photo by Ferdi Uzun/Anadolu via Getty Images)

Runners gather at the start line for the annual “Santa Speedo Run”, a charity race through the streets of the Back Bay neighborhood of Boston. (Photo by Gretchen Ertl/Reuters)