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I should note, Ed Yong writes about the "animal populations reduced by 60%" report in The Atlantic and clarifies a few things.
https://www.theatlantic.com/science/archive/2018/10/have-we-really-kille...

The good news is that the 60% figure is the average decrease in population size. Due to the animals that were measured having different population sizes, it does not mean that the number of animals has decreased by 60%.

To understand the distinction, imagine you have three populations: 5,000 lions, 500 tigers, and 50 bears. Four decades later, you have just 4,500 lions, 100 tigers, and five bears (oh my). Those three populations have declined by 10 percent, 80 percent, and 90 percent, respectively—which means an average decline of 60 percent. But the total number of actual animals has gone down from 5,550 to 4,605, which is a decline of just 17 percent.

The bad news is that some animals have increased in population size, which means that others have decreased even more dramatically.

The average 60 percent decline across populations also obscures the fates of individual species. In the hypothetical scenario above, lions are still mostly fine, the tigers are in trouble, and the bears are on the brink of extinction. And of the species covered in the actual Living Planet Index, half are increasing in number, while only half are decreasing. This means that for those that are actually in decline, the outlook is even worse than it first appears.