A heat-stressed koala waits as a resident pours water on its back on December 19, 2015 in Adelaide, Australia. Adelaide is experiencing an extreme heatwave, with temperatures reaching over 40 degrees for five consecutive days. (Photo by Morne de Klerk/Getty Images)

A bully greenfinch (left) got its comeuppance when a small but fiery dunnock (right) defended itself with its talons in Suffolk, United Kingdom on April 18, 2022. The smaller bird was perched peacefully before the finch burst onto the scene and aggressively squared up to the dunnock. But as the finch tried to peck at the dunnock, the small brown bird expertly used its foot to slam its mouth shut. (Photo by Paul Sawer/Solent News & Photo Agency)

A Filipino worker arranges roasted pigs which they sell in suburban Quezon city, Philippines on Tuesday, December 23, 2014. Roasted pig is popular during Filipino celebrations and traditionally served during a Christmas eve dinner called “Noche Buena” in this predominantly Roman Catholic nation. (Photo by Aaron Favila/AP Photo)

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)

An owl peeps out from behind a rusty piece of farming equipment in Teddesley Park, Staffordshire, UK in the last decade of July 2025. (Photo by David Akers/Solent News & Photo Agency)

This picture taken on February 1, 2015 shows participants competing in a tofu (beancurd) wrestling competition in Fogang county, south China's Guangdong province. Participants, mostly women, fight it out in an inflatable pool which is filled with nearly two tons of fresh milk and tofu, in a promotion to attract tourists for the upcoming Chinese Lunar New Year holiday. The upcoming Chinese lunar new year of the sheep, which will fall on February 19 this year, marks the biggest festival of the year in China as hundreds of millions of people journey across the country to celebrate the season with their families. (Photo by AFP Photo/Stringer)

Nessie, a California sea lion pup recently born at Blair Drummond Safari and Adventure Park, near Stirling, UK. Picture date: Thursday July 11, 2024. (Photo by Andrew Milligan/PA Images via Getty Images)

A visitor takes in a view of the downtown district from Twin Peaks on Friday, January 9, 2015, in San Francisco. (Photo by Marcio Jose Sanchez/AP Photo)