Fairly useful, despite a few wienie treehugging moments, which I suppose is par for the course with this sort of thing. Perhaps the silliest was the following...after explaining that the cowbird is a "nest parasite," Griggs goes on: "The cowbird's threat to some species is so serious that many bird conservationists give the problem top priority. However, the bird did not create the problem. We created it by altering the landscape." So it's okay for a bird to be a parasite, but not us (lol).
Also, the book tends to be a bit specialized and birdwatcherish. I mean, it's not really likely that people concerned with "marks" and logging their species views are gonna pick up a volume about the tweeters you find in your backyard. Still, I suppose that sort of stuff is easy enough to ignore.