Big animals are being systematically wipped, but smaller animals had probably increased in total number. With the same amount of grass you can have 1 cow, or lets say '50' rabbits, or '1000' voles, or "1billion" of nematodes. I we could really measure it, I bet that we would find a big increase in number, and a big decrease in diversity.
Not just vertebrates: https://journals.plos.org/plosone/article?id=10.1371/journal...
It's biomass that's decreasing, not just numbers: http://www.climatecentral.org/news/amazon-may-lose-65-percen...
Yes, maritime animals too: https://www.int-res.com/articles/theme/m512p155.pdf
And yes, plant biomass too: http://www.pnas.org/content/115/25/6506 (This one's on a much longer timeline, so hard to compare)
And much more rodents also, of course.
We could assume that more or less a half of the biomass of each tree in a temperate forest is under the surface. Number of animals is not a good measure to explain the current situation.