I haven't read the later books in the Southern Reach series, but I imagine if the phenomena had eventually extended past the swamp to interact with horses and wolves the result would have looked very much like this:
All animals are beautiful. All animals are wonderful. All animals OH GOD OH NO. pic.twitter.com/O3SlSj48o0
— AC "Young Santa" Stuart (@NoobtheLoser) December 4, 2019
It seems to be a knockoff of "Twilight Hunters" from the Trail of Painted Ponies series:
The series includes...
Read this story at Boing Boing