A supporter of the Houthi movement attends a rally marking the birth anniversary of Prophet Mohammed, in Sanaa, Yemen December 11, 2016. (Photo by Khaled Abdullah/Reuters)

CHINA: Customers eat at a restaurant as a cooked pig sits on a cart on the street outside in Hong Kong, China, December 12, 2016. (Photo by David Gray/Reuters)

A pedestrian carries an umbrella as they stroll past an advertisment as a rainstorm moves through Sacramento, Calif., Wednesday, February 13, 2019. Rain is falling widely in Northern California and is expected to spread south. (Photo by Rich Pedroncelli/AP Photo)

Revelers pose before the start of the Los Angeles Pride parade on June 9, 2019 in West Hollywood, California. The 49th annual parade, celebrating LGBTQ identity, drew thousands to the streets of West Hollywood. (Photo by Mario Tama/Getty Images)

Traffic lights feature illustrations of a homosexual couple in downtown Frankfurt Main, Germany, 18 July 2019. An annual gay pride parade will take place on 20 July 2019 in Frankfurt to commemorate Christopher Street Day (CSD). The event commemorates the riots that erupted following a police raid in 1969 at a gay bar on Christopher Street in Greenwich Village, New York City. (Photo by Armando Babani/EPA/EFE)

Television personality Farrah Abraham (C) enjoys adult entertainment as she hosts the VIP Back Door Key party at the Crazy Horse III Gentlemen's Club on August 4, 2017 in Las Vegas, Nevada. The newly launched VIP membership program offers patrons exclusive entrance to the club through the back door. (Photo by Bryan Steffy/WireImage)

Bloodthirsty by Thomas P. Peschak, Germany/South Africa — winner, Behaviour: birds. When rations run short on Wolf Island, in the remote northern Galápagos, the sharp-beaked ground finches become vampires. Their sitting targets are Nazca boobies and other large birds. The finches rely on a scant diet of seeds and insects, which regularly dries up, so they drink blood to survive. ‘I’ve seen more than half a dozen finches drinking from a single Nazca booby,’ says Tom. Rather than leave their nests the boobies tolerate the vampires, and the blood loss doesn’t seem to cause permanent harm. (Photo by Thomas P. Peschak/2018 Wildlife Photographer of the Year)

The secretive indri (Indri indri) of Madagascar, the largest living lemur. It is also critically endangered and highly evolutionarily distinct with no close relatives, which makes its branch one of most precarious on the mammal evolutionary tree. In the likely event that the indri goes extinct, we will lose 19m years of unique evolutionary history from the mammal tree of life. (Photo by Pierre-Yves Babelon/Aarhus University)