A civil defence volunteer wearing a Covid-19 coronavirus-themed helmet holds a placard as he takes part in an awareness campaign at a market in New Delhi on November 25, 2020. (Photo by Sajjad Hussain/AFP Photo)

A woman walks up a stairway painted in the rainbow colors in Bucharest, Romania, Saturday, July 11, 2020. Romania reported 698 new COVID-19 infections in the last 24 hours, the highest level since the pandemic reached the country in February. (Photo by Vadim Ghirda/AP Photo)

Constanza Mena poses for a photo during a red-nosed walk organized by the Flying Laughter clown group amid the new coronavirus pandemic, in downtown Santiago, Chile, Wednesday, April 28, 2021. The group aims to show that people do not lose the right to play and have fun in the street while pandemic protective measures are in effect. (Photo by Esteban Felix/AP Photo)

Protesting women shout slogans during a demonstration against sexual violence in front of the governor's mansion in San Juan, Puerto Rico on May 3, 2021. The demonstrators denounce the inaction and slowness of the state in implementing the executive order declaring a state of emergency against gender-based violence. (Photo by Ricardo Arduengo/AFP Photo)

Police officers look on as they stand guard to secure the area where Dutch celebrity crime reporter Peter R. de Vries, known for his reporting on some of the most renowned criminals in the Netherlands, was reportedly shot and seriously injured, in Amsterdam, Netherlands, July 6, 2021. (Photo by Eva Plevier/Reuters)

A child is pictured with the face covered in blood during a religious procession to mark Ashura in Nabatieh, southern Lebanon on August 19, 2021. (Photo by Aziz Taher/Reuters)

In this Saturday, June 24, 2017 file photo, Zeid Ali, 12, left, and Hodayfa Ali, 11, comfort each other after their house was hit and collapsed during fighting between Iraqi forces and Islamic State militants in Mosul, Iraq. The Ali cousins said some of their family members are still under the rubble. (Photo by Felipe Dana/AP Photo/File)

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)