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)

Andrew Parkinson, animal behaviour category winner: Crepuscular Contentment, Derbyshire. “In 15 years of working with badgers I’ve never seen a badger sit out in the open to have a scratch. I was sat concealed behind a tree and downwind so it was especially nice that the badger had his back to me, demonstrating just how inconspicuous and inconsequential my presence was”. (Photo by Andrew Parkinson/British Wildlife Photography Awards 2017)

In this 2017 photo provided by Simon Pierce, Jonathan Green checks on a fin-mounted satellite tag on a whale shark in the Galapagos Islands area of Ecuador. Despite typically being bigger than a double-decker bus, the elusive whale shark has only tiny, almost useless teeth. It's also one of the least understood animals in the ocean. (Photo by Simonjpierce.com via AP Photo)

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)