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 young Bengal tiger cub smuggled into the US and seized at the Mexico border is displayed for the media during Operation Jungle Book at the US Fish and Wildlife Service in Torrance, California on October 20, 2017. Operation Jungle Book, a law enforcement initiative led by the US Fish and Wildlife Service that targeted wildlife smuggling, resulting in federal criminal charges against defendants who allegedly participated in the illegal importation and/ or transportation of numerous animal species – including a tiger, monitor lizards, cobras, Asian “lucky” fish, exotic songbirds and several coral species. (Photo by Mark Ralston/AFP Photo)

A participant in the Downtown Parade kicks off the Houston Livestock Show and Rodeo in Houston, Texas, US on February 25, 2023. (Photo by Reginald Mathalone/NurPhoto/Rex Features/Shutterstock)

A woman talks on her cellphone as she walks around Tajrish commercial district without wearing the mandatory Islamic headscarf in northern Tehran, Iran, Saturday, April 29, 2023. More women are choosing not to wear the mandatory headscarf, or the hijab, publicly in Iran. Such open defiance of the law follows months of protests over the September death of 22-year-old Mahsa Amini while in the custody of the country's morality police, for wearing her hijab too loosely. (Photo by Vahid Salemi/AP Photo)

Participants take part in a high-wheel bicycle race in the Frederick county, in Maryland, United States on July 15, 2023. (Photo by Celal Gunes/Anadolu Agency via Getty Images)

A tern chick takes its first steps in the first decade of June 2024 at Nickerson Beach, New York, a common nesting location. (Photo by Suraj Ramamurthy/Solent News)

Photographer John Fatkin captured these jaw-dropping images of a rainbow and ferry on the River Tyne, England, with the iconic red-painted Herd Groyne Lighthouse. (Photo by Tom Fatkin/Cover Images)

Hot-air balloons glide over the historical Cappadocia region with Turkish flags to mark August 30 Turkiye's Victory Day in Nevsehir, Turkiye on August 30, 2023. (Photo by Behcet Alkan/Anadolu Agency via Getty Images)