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 picture made available on 14 July 2016 shows Greyhound dogs racing at the Wentworth Park Stadium in Sydney, New South Wales (NSW), Australia, 13 July 2016. Greyhound racing has returned to Sydney's Wentworth Park and other NSW tracks for the first time since the state government announced plans to ban it. NSW Premier Mike Baird announced last week plans to shut down the sport in NSW following a Special Commission of Inquiry report that found “chilling” evidence of systemic animal cruelty within the industry. (Photo by David Moir/EPA)

Bar girls use their mobile phones outside a bar along the Walking Street where bars and sеx scenes are a commonplace July 31, 2016 in Pattaya, Thailand. Thailand's first female minister of tourism would like the sеx trade that is a huge business in the country to be banned. Tourists flock to Thailand for many sights including beautiful beaches but also for sеx tourism. Cities like Bangkok and Pattaya are well known as hubs of the Southeast Asian sеx trade, despite the fact that prostitution has been illegal in Thailand since 1960. (Photo by Paula Bronstein/Getty Images)

A bar girl shows off her sexual desires along the Walking Street where bars and sеx scenes are a commonplace July 31, 2016 in Pattaya, Thailand. Thailand's first female minister of tourism would like the sеx trade that is a huge business in the country to be banned. Tourists flock to Thailand for many sights including beautiful beaches but also for sеx tourism. Cities like Bangkok and Pattaya are well known as hubs of the Southeast Asian sеx trade, despite the fact that prostitution has been illegal in Thailand since 1960. (Photo by Paula Bronstein/Getty Images)

A woman sings as Tibetans celebrate the 80th birthday of their spiritual leader, the Dalai Lama, in Kathmandu, Nepal, Monday, July 6, 2015. Around 1,000 monks and other Tibetans gathered at the school compound to celebrate their spiritual leader's birthday. Exiled Tibetans allowed celebrating the Dalai Lama's birthday only inside school compound and refugee camps as long as the facilities do not contain slogans or banners protesting against China. Nepalese government has banned all kinds of Tibetan activities against Chinese rule in Tibet. (Photo by Niranjan Shrestha/AP Photo)

Demonstrators take part in a mass “face-sitting protest” outside the Houses of Parliament in central London on December 12, 2014, as they protest against changes to p*rnography regulations. An amendment to the 2003 Communities Act applies the same strict rules to p*rn bought online as those included in the guidelines set out by the British Board of Film Censors for DVDs. The new laws ban films that feature s*x acts, such as spanking, caning, strangulation, aggressive whipping, humiliation, and face-sitting. Ministers say the rules have been brought in to protect s*x workers. But campaigners say it is an attempt to censor and control the internet. Paid-for videos shot overseas and viewed online in the UK are not affected by the new rules, which were introduced on December 2, 2014. (Photo by Leon Neal/AFP Photo)

Ukrainian police detain activists of women's rights group Femen as they protest against homophobia outside the parliament building in Kiev, Ukraine, November 12, 2015. Femen and gay rights activists are pushing parliament to adopt bills, including one that would ban discrimination in the workplace based on sexuality, which is included in a package of laws to liberalise Ukraine's visa regime with the EU. (Photo by Gleb Garanich/Reuters)

Kalei Ferrin,3, holds a sign up in support of gay rights during the San Diego gay pride parade July 16, 2011 in San Diego, California. About 200 active-duty troops and veterans from every branch of the military participated for the first time in the march as the ban on the government policy on homosexuals serving in armed forces, or “Don't ask Don't Tell”, remains in flux in the justice system. (Photo by Sandy Huffaker/Getty Images)