Betts and Christopher Wolf, an Oregon State Ph.D. student in forest ecosystems and statistics along with six co-authors, used forest data assembled by Matthew Hansen at the University of Maryland and categories of extinction risk for 19,432 verterbate species, the so-called Red List, maintained by the International Union for the Conservation of Nature.

New Scientist, July 12, 2017: Chris Wolf and William Ripple at Oregon State University looked at historical accounts of large carnivores and maps of their preferred habitat around AD 1500, and found that they are now present in just a third of the land area they occupied back then. Of the 25 species analysed, all weighing more than 15 kilograms, 15 had lost more than half their range. Publication: Range contractions of the world’s large carnivores

ScienceDaily, May 23, 2017: "It will be interesting to see the influence of large predators on smaller predators in other parts of the world, especially the role of the big cats such as jaguars, leopards, lions and tigers," said co-author William Ripple of Oregon State University.

Professor William Ripple, Co-author and Oregon State University Professor concluded: 'The Megafauna Conservation Index is an important first step to transparency – some of the poorest countries in the world are making the biggest investments in a global asset and should be congratulated, whereas some of the richest nations just aren’t doing enough.' Publication details.