I agree with Gary Bletsch's summary. One detail. Trinidad and Tobago
as well as the ABC islands (Aruba, Bonaire and Curacao) were excluded
from the very early West Indies bird guide book by James Bond
. There is a nice map in his book showing the "Bond line" defining
the biological boundary of the West Indies islands. Subsequent guide
books follow James Bond's geographical limits for the West Indies,
including our latest book that was published last year: "Birds of the
West Indies"
https://www.lynxeds.com/product/birds-of-the-west-indies/ which also
covers Turks and Caicos.