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)

American actress Paris Jackson pulls faces at photographers during the “Melbourne Cup” race day festivities in Melbourne, Australia on November 7, 2017. (Photo by Media-Mode/Splash News and Pictures)

Rescuers attempt attempt to push stranded whales back into the ocean at Ujong Kareng beach in Aceh province, Indonesia, Monday, November 13, 2017. An official said a small pod of whales was stranded at the beach and attracted hundreds of onlookers who posed for pictures with them. (Photo by AP Photo/Zulkarnaini)

A participant Saint Nicholas parade walks from house to house dressed in the traditional devil and Nicholas costumes in Francova Lhota district of Zlin, Czech Republic on December 3, 2017. This type of parade is one of the most popular age old tradition in a few villages in Wallachia region (eastern part of Czech Republic). Saint Nicholas walks the streets going from house to house three days and Saint Nicholas gives sweets to children and the devils get up to mischief. (Photo by Lukas Kabon/Anadolu Agency/Getty Images)

Drag queen Courtney Act (real name Shane Jenek) attends the Celebrity Big Brother male contestants launch night at Elstree Studios on January 5, 2018 in Borehamwood, England. The drag queen was left over-exposed on last show after her outfit apparently fell off. (Photo by Mike Marsland/WireImage)

Residents recently returning to their area cleared by government troops react as they ride a tricycle a day after President Rodrigo Duterte declared the liberation of Marawi city in southern Philippines Wednesday, October 18, 2017. Sporadic explosions continue Wednesday as Philippine soldiers fought to gain control of the last pocket of Marawi controlled by Islamic militants. (Photo by Bullit Marquez/AP Photo)

Russian cadets march during the annual cadet schools get-together in Moscow, Russia on March 30, 2018. (Photo by Mladen Antonov/AFP Photo)

In this photo taken on Monday, August 5, 2019, a family watches explosions at a military ammunition depot near the city of Achinsk in eastern Siberia's Krasnoyarsk region, in Achinsk, Russia. Russian officials say powerful explosions at a military depot in Siberia left 12 people injured and one missing and forced over 16,500 people to leave their homes. (Photo by Dmitry Dub/AP Photo)