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 jogger runs on the bank of Donaukanal channel in central Vienna, Austria, September 5, 2016. (Photo by Heinz-Peter Bader/Reuters)

Migrant children play with leaves during Christmas Eve at a shelter, as they travel with their parents as part of a caravan with humanitarian visas to transit throughout the country, in Monterrey, Mexico on December 24, 2021. (Photo by Daniel Becerril/Reuters)

Lava gushes from the southern side crater of Mt. Etna, Europe's largest active volcano, near Catania, southern Italy Sicily, early Tuesday, May 25, 2021. (Photo by Salvatore Allegra/AP Photo)

Olga Conover of Palm Bay, Fla., walks down the bridge at sunset carrying her merged American-Ukraine flag near the end of a march marking the one-year anniversary of Russia invading Ukraine, late Thursday afternoon, February 23, 2022, in Melbourne, Fla. A small but passionate group of Ukraine supporters took the Melbourne Causeway to show their support, organized by the Ukrainian Space Coast group. (Photo by Malcolm Denemark/Florida Today via AP Photo)

A person rides a swing hanging from a crane with hot air balloons fly in the background in Nevsehir, Turkey on October 14, 2021. Tourists and those who want to take photos set up swings on the cranes they rent and then have their photos taken in the setting created by hot air balloons in the backgrounds. (Photo by Behcet Alkan/Anadolu Agency via Getty Images)

Penguins Momo and Omochi are seen while the projection mapping images is being cast during a media preview for their free online animal shows for children and families staying at home during Golden Week holidays due to the coronavirus disease (COVID-19) lockdown, at the Aqua Park Shinagawa in Tokyo, Japan on April 30, 2020. (Photo by Issei Kato/Reuters)

An orphan plays with her new hula hoop during the food and toy distribution, for total about 500 orphans in 11 orphanages, by National Muslim COVID-19 Response Committee to celebrate Eid al-Fitr, the Muslim holiday which marks the end of the fasting month of Ramadan at Good hope markazil Banatil Islamia orphans centre in Nairobi, Kenya, on May 25, 2020. (Photo by Yasuyoshi Chiba/AFP Photo)