A frontline worker reacts as she receives a dose of AstraZeneca's COVISHIELD vaccine, produced by the Serum Institute of India, during the coronavirus disease (COVID-19) vaccination campaign at a medical centre in New Delhi, India, February 24, 2021. (Photo by Anushree Fadnavis/Reuters)

A health worker applies a dose of the AstraZeneca vaccine during the first day of a three-day COVID-19 vaccination campaign for people over age 35 in the Complexo da Maré favela of Rio de Janeiro, Brazil, Brazil, Thursday, July 29, 2021. Some recipients will be monitored to study the rate of protection the vaccines provide and the extent to which virus variants are circulating. (Photo by Bruna Prado/AP Photo)

A man sleeps at Beirut's Corniche, a seaside promenade, in Lebanon May 2, 2016. (Photo by Alia Haju/Reuters)

A photo taken from the International Space Station shows Hurricane Lane in the early morning hours near Hawaii, August 22, 2018. (Photo by Courtesy @astro_ricky/NASA/Handout via Reuters)

Leonhard Nienbling is shown with his 6-month old pet baboon Jackl, who holds a 6-month old kitten, its playmate, June 29, 1952. Niebling has quite an animal collection at his home in Zirndorf, Germany. (Photo by Heinrich Sanden/AP Photo)

A festival goer spins a light strip as she dances to electronic music in front of the Belleville stage during the 45th edition of the Paleo Festival, in Nyon, Switzerland, 24 July 2022. The Paleo is the largest open-air music festival in the western part of Switzerland. (Photo by Valentin Flauraud/EPA/EFE)

A member from the Iraqi security forces beats an Islamic State insurgent, who was captured in Tikrit April 1, 2015. Iraqi troops and Shi'ite paramilitary fighters were battling Islamic State on Wednesday in northern Tikrit, which officials described as the Sunni Muslim militant group's last stronghold in the city. (Photo by Alaa Al-Marjani/Reuters)

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)