Comment by snvzz
3 hours ago
Read that sentence carefully.
They're counting cat-caused as anthropogenic i.e. part of anthropos-caused aka human-caused. And "single largest group" could be 1% if there are a lot of groups and each happens to be smaller than 1%.
I have read both the sentence and the abstract carefully, one of the other big antropogenic factors is "building colissions" which by itself is over one billion bird deaths.