The first is an article comparing what the summer is now in Arizona and what it used to be in the 1800's when thick-billed parrots still migrated to USA.
The second is from World Parrot Trust and talks about their status and what is been done for them.
And the third one is a loooong but very comprehensive and detailed plan for their recovery of the joint Mexico-USA governments.
http://knau.org/post/earth-notes-thick- ... a#stream/0
https://www.parrots.org/projects/thick-billed-parrot
https://www.fws.gov/southwest/es/arizon ... -15-12.pdf