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 window cleaner passes a lighter to his colleague while rappelling from a new building in Tianjin March 23, 2007. (Photo by Reuters/Stringer)

Ring-tailed lemurs sit on the hood of a truck while snacking inside the Buin Zoo in Santiago, Chile, Tuesday, June 15, 2021. The largest private zoo in Chile, experiencing a serious economic situation due to the closure of its doors as a result of the prolonged quarantine measures, has started a campaign coined, “Sponsor an Animal”, to raise money to maintain the animals. (Photo by Esteban Felix/AP Photo)

A flying lemur glides through the air in West Java, Indonesia in the first decade of October 2023. The photographer said the animal veered away from him at the last minute. (Photo by Dzul Dzulfikri/Animal News Agency)

A confiscated pet lion poses with a dog as it arrived back home from the Phnom Tamao Wildlife Rescue Center after Prime Minister Hun Sen ordered authorities to return the animal in Phnom Penh, Cambodia, July 5, 2021. (Photo by Cindy Liu/Reuters)

A gaggle of goslings huddle together under the protective wing of a parent along the bank of the Deschutes River as a heavy downpour passes through Bend, Oregon, late Wednesday, April, 20, 2106 afternoon. (Photo by Ryan Brennecke/The Bulletin via AP Photo)

A saddle-billed stork stands in the grassland at the Nairobi National Park near Nairobi, Kenya January 23, 2017. (Photo by Thomas Mukoya/Reuters)

A seal infront of a passing cruise ship on the shore between Sandhaven village and Fraserburgh in Scotland in August 2023. (Photo by Mark Grant/Caters News Agency)