Passengers travel in an overcrowded train in the eastern Indian city of Patna, February 23, 2010. (Photo by Krishna Murari Kishan/Reuters)

Female of pygmy hippopotamus called Malaya from Netherlands in zoo in Dvur Kralove nad Labem, Czech Republic, February 22, 2016. (Photo by David Tanecek/CTK via ZUMA Press)

In this February 19, 2017 photo, a couple dances during the “If you don't give me....then you lend me” Carnival street party on Ipanema beach, in Rio de Janeiro, Brazil. The typical view of Carnival in Brazil is anything goes, with no headdress too big, no outfit too small, no song too ribald, but this year some organizers of the world's best known party are drawing the line at lyrics that are sexist, homophobic or racist. (Photo by Silvia Izquierdo/AP Photo)

Russian honor guard soldiers warm up prior a rehearsal for the Victory Day military parade in St. Petersburg, Russia, Wednesday, May 3, 2017. The parade will take place at Dvortsovaya (Palace) Square on May 9, to celebrate 72 years after the victory in WWII. (Photo by Dmitri Lovetsky/AP Photo)

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)

People watch a forest fire in Funchal, Madeira Island, Portugal, 09 August 2016. The fire has led to the evacuation of 400 people. Portugal remains on high alert as a wave of wildfires has swept the country with around 350 isolated fires affecting swathes of the countryside. (Photo by Gregório Cunha/EPA)

A Rohingya refugee child with thanaka paste is seen in Cox's Bazar, Bangladesh, July 4, 2018. (Photo by Mohammad Ponir Hossain/Reuters)

A tamed hawk sits on a chair next to a participant during a traditional hunting contest in Almaty, Kazakhstan on December 1, 2018. (Photo by Pavel Mikheyev/Reuters)