||Ceballos G, Ehrlich PR, Dirzo R. Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines. Proc Natl Acad Sci U S A. 2017 Jul 25 114(30):E6089-E6096. doi: 10.1073/pnas.1704949114 p.E6090 left column 2nd paragraphPubMed ID28696295
|| World Wide Fund for Nature (2016) Living Planet Report 2016. Risk and resilience in a new era. (WWF International, Gland, Switzerland). Available at wwf.panda.org/about_our_earth/all_publications/lpr_2016/. Accessed June 10, 2017
||Abstract: "That conclusion is based on analyses of the numbers and degrees of range contraction (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species."
||P.E6090 left column 2nd paragraph: "The most recent Living Planet Index (LPI) has estimated that wildlife abundance on the planet decreased by as much as 58% between 1970 and 2012 (primary source)."