My novel "Flight of the Goose" has a sub theme of species extinction (Leif, "the Birdman", a draftdodging scientist and one of the protagonists, is in the Arctic trying to find Tallins Goose - thought to have gone extinct).
The book was written some years ago and indeed was a twinkle in my eye up to thirty years ago when I was obsessing about the knowledge I had gained in ecological study pointing to the extinction of most species on Earth within my lifetime and very probably the extinction or at least severe culling of the dominant hominid.
Here is an article from today about the 6th Extinction
. I think "up to half" gone by the end of this century is greatly optimistic but folks don't want to be scared too badly.