A tiger plays in water at a tiger zoo in Chaing Mai, Thailand on March 31, 2021. (Photo by Soe Zeya Tun/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)

“The aye-aye (Daubentonia madagascariensis) is a lemur, a strepsirrhine primate native to Madagascar that combines rodent-like teeth and a special thin middle finger to fill the same ecological niche as a woodpecker. It is the world's largest nocturnal primate, and is characterized by its unusual method of finding food; it taps on trees to find grubs, then gnaws holes in the wood and inserts its narrow middle finger to pull the grubs out. The only other animal species known to find food in this way is the striped possum. From an ecological point of view the aye-aye fills the niche of a woodpecker as it is capable of penetrating wood to extract the invertebrates within”. – Wikipedia

Photo: In this handout image from Bristol Zoo is seen the first captive bred aye-aye in the UK named “Kintana” (meaning star in Malagasy) April 15, 2005 at Bristol Zoo Gardens, England. The zoo announced today only the second baby aye-aye to be hand-reared in the world (the first was in Jersey Zoo) and has now made his first public appearance since his birth on 11 February 2005. (Photo by Rob Cousins/Bristol Zoo via Getty Images)

A gibbon drinks from a soft drink bottle, given by a tourist, at a zoo in Kunming, Yunnan province, June 18, 2015. (Photo by Wong Campion/Reuters)

Central Park Zoo, New York, 1967. (Photo by Garry Winogrand)

A tiger yawns next to a piglet at the Sriracha Tiger Zoo, in Chonburi province, Thailand, June 7, 2016. (Photo by Chaiwat Subprasom/Reuters)

A panda bear sits on a logs in a zoo on January 15, 2015 in Hangzhou, China. (Photo by Feature China/Barcroft Media)

A baby Chimpanzee plays in its enclosure at Taronga Zoo July 14, 2006 in Sydney, Australia. (Photo by Ian Waldie/Getty Images)