You might include the Carolina Parakeet in your study. It was killed
because of depradations on agricultural crops and apparently disappeared
when its population fell below a critical mass. There was a thread re CAPA
on either Tweeters or Birdchat some months ago, so you might search the
archives. There appeared to be some pretty knowledgable people out there.

Herb Curl

h.curl at hazmat.noaa.gov "You may be only young once but you can be
Hazmat/NOAA, 7600 Sand Pt. Wy., NE immature the rest of your life."
Seattle, WA 98115-0070
(206) 526-6272