Googling, a lot of the articles on species decline seem to point to the World Wildlife Foundation and The Living Planet, a survey published as a joint collabora

Googling, a lot of the articles on species decline seem to point to the World Wildlife Foundation and The Living Planet, a survey published as a joint collaboration between the WWF and the Institute of Zoology. Obviously, there is probably some bias due to this being in part from a conservation advocacy group. However, the methodology does appear to be documented in a peer-reviewed paper [2]. So I'd personally give it a fair more weight than mere anecdote. [1] https://www.worldwildlife.org/pages/living-planet-report-2016 https://www.worldwildlife.org/pages/living-planet-report-201... [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569448/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569448/