A baby Black-crowned Night Heron squawks in its incubator while being cared for at City Wildlife rescue and rehabilitation center in Washington, DC on May 31, 2017. The heron is one of several that have been brought to CW by the staff at The National Zoo over the past few years. (Photo Linda Davidson/The Washington Post)

The National Geographic Photo Ark is a travelling exhibition of photographer Joel Sartore’s quest to create a photo archive of biodiversity around the world. So far, Sartore has captured studio portraits of more than 6,000 species – a number that he hopes to double. On 1 July, the ark will open at Melbourne zoo – the first time it has been exhibited in the southern hemisphere. More than 50 portraits will be on display, including many of Australian endangered animals being protected by programs at the zoo itself. These captions have been edited from text supplied by Melbourne zoo. Here: Barking owl. (Photo by Joel Sartore/National Geographic Photo Ark/The Guardian)

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)

Women dancing at the disco club Xenon in New York City, USA in 1978. Xenon was a popular disco in Manhattan in the late 1970s and early 1980s. It was the only nightclub popular enough to compete with Studio 54. (Photo by Waring Abbott/Getty Images)

A keeper feeds a four-week-old jaguar while presenting it to the media, at a zoo in Ciudad Juarez, Mexico, October 14, 2015. (Photo by Jose Luis Gonzalez/Reuters)

In this September 10, 1977, file photo, from left, Hua Guofeng, Chinese Communist Party (CCP) chairman and Mao Zedong's immediate successor; Ye Jianying, CCP vice chairman and future ceremonial head of state; Deng Xiaoping, no formal titles at the time but soon to emerge as paramount leader during the reform era; Li Xiannian, CCP vice chairman and future president; Wang Dongxing, head of the leadership bodyguard unit who helped topple the Gang of Four, view the body of later Chinese leader Mao Zedong in Beijing. (Photo via AP Photo)

One of the largest paddle steamers afloat in Britain is the H.M.S. Royal Eagle, former peacetime excursion boat which carried passengers on pleasure jaunts from Tower Bridge to Southend, Ramscate and Margate. Commissioned two years ago as a warship of the Royal Navy, the craft has been in action 52 times against enemy aircraft. The Eagle took part in the evacuation from Dunkirk where she was dive-bombed 48 times and brought home nearly 3,000 British troops. Members of the crew cleaning the paddle boxes of H.M.S. Royal Eagle in London on January 18, 1943. (Photo by AP Photo)

Sulphur miners haul sulphur up an arduous path out of Indonesia’s Ijen volcano. The average carry out of the volcano is 70 kilograms per load per miner. The all-time record carry was 120 kilograms in one load. Extraordinary numbers given most of the miners only weigh around 55 kilograms. Ijen volcano, Indonesia, 2012. (Photo by Hugh Brown/South West News Service)