Orphaned mountain gorilla, Ndakasi, lies in the arms of her caregiver, Andre Bauma, on September 21, 2021 shortly before her death, which the park confirmed on September 26. Mr Bauma and others at the Senkwekwe Mountain Gorilla Center had cared for Ndakasi and other orphans for 13 years. Ndakasi had suffered a prolonged illness prior to her death. This is the only mountain gorilla orphanage in the world and takes in mountain gorilla orphans who have lost their families to poaching or conflict. A number of the orphans here were rescued from sales by poachers in sting operations carried out by Congolese National Park Authority (ICCN) rangers. (Photo by Brent Stirton/Getty Images)

In this handout image provided by Parks Australia, thousands of red crabs are seen walking in a drain on November 23, 2021 in Christmas Island. The annual migration of red crabs begins with first rains of the wet season on Christmas Island, usually around October or November. Millions of the red crabs make their way across the island to the ocean to mate and spawn. (Photo by Parks Australia via Getty Images)

A veterinarian inspects a cow for foot-mouth-disease ahead of Eid al-Adha, the feast of the sacrifice marking the end of the Hajj pilgrimage to Mecca and commemorates Prophet Abraham's readiness to sacrifice his son to show obedience to Allah, at a cowshed in Lambaro, Aceh province on July 7, 2022. (Photo by Chaideer Mahyuddin/AFP Photo)

Female dancers line up before they perform during the opening of Bali Arts Festival in Bali, Indonesia, Sunday, June 18, 2023. The island of Bali is currently holding a month-long annual Bali Arts Festival from June 18 until July 16. (Photo by Firdia Lisnawati/AP Photo)

Farmers play with mud as they plant rice on “National Paddy Day of Nepal” in Dhading district on June 29, 2024. (Photo by Prakash Mathema/AFP Photo)

Young female Ibex on the fork of Disteis (2,200 m), near the top of the Jof di Montasio (Friuli, Italy). (Photo by Stefano Zocca)

Children eat watermelons to meet the “beginning of autumn” at a kindergarten in Handan, China on August 7, 2015. Chinese tradition to eat watermelons or peaches before that day symbolises “biting away summer”. The solar term ‘beginning of autumn’ falls on 8 August this year. (Photo by Xinhua/REX Shutterstock)

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)