Singer Rihanna prepares for a photoshoot with photographer Annie Leibovitz in Havana, Cuba, May 28, 2015. (Photo by Reuters/Stringer)

The Jet Propulsion Lab team's RoboSimian robot turns on a valve at a simulated disaster-response course during day one of the Defense Advanced Research Projects Agency (DARPA) Robotics Challenge finals in Pomona, California, June 5, 2015. (Photo by David McNew/Reuters)

Global wildlife populations will decline by 67% by 2020 unless urgent action is taken to reduce human impact on species and ecosystems, warns the biennial Living Planet Index report from WWF (World Wide Fund for Nature) and ZSL (Zoological Society of London). From elephants to eels, here are some of the wildlife populations most affected by human activity. Here: The maned wolf is among the large mammals in the Brazilian Cerrado that are threatened by the increasing conversion of grasslands into farmland for grazing and growing crops. (Photo by Ben Cranke/Nature Picture Library/Alamy Stock Photo)

A cadet from the Interior Ministry with the word Fidel painted on her face attends a rally honoring the late Cuban leader at the Revolution Plaza in Havana, Cuba, Tuesday, November 29, 2016. Schools and government offices were closed Tuesday for a second day of homage to Fidel Castro, with the day ending in a rally on the wide plaza where the Cuban leader delivered fiery speeches to mammoth crowds in the years after he seized power.Fidel Castro passed away Friday Nov. 25. He was 90. (Photo by Ramon Espinosa/AP Photo)

Law enforcement officers stand, with some turning their backs, as New York City Mayor Bill de Blasio speaks on a monitor outside the funeral for NYPD officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. Tens of thousands of law enforcement officers from across the country gathered on Sunday for the funeral of the second of two New York City policemen killed last month in an ambush that galvanized critics of Mayor de Blasio. (Photo by Shannon Stapleton/Reuters)

Secondary school graduates play in a fountain as they celebrate the last day of school, traditionally called the “last bell” in central Kiev, Ukraine on May 31, 2019. (Photo by Valentyn Ogirenko/Reuters)

Secondary school graduates play in a fountain as they celebrate the last day of school, traditionally called the “last bell” in central Kiev, Ukraine on May 31, 2019. (Photo by Valentyn Ogirenko/Reuters)

A Colombian Nukak Maku Indian boy gestures in a refugee camp at Agua Bonita near San Jose del Guaviare of Guaviare province September 3, 2015. Since emerging from the jungle in 2005, half naked and carrying blowpipes, the Nukak have lived in settlements near the frontier town of San Jose del Guaviare, a humid outpost in the Amazon 400 km (250 miles) southeast of the capital Bogota. (Photo by John Vizcaino/Reuters)