Hi Deb, I've just been looking into this myself. It looks like birding in the immediate vicinity of PV may not be all that amazing, but birding in the immediate vicinity of San Blas looks utterly mind blowing.
If you have time it must be worth getting to San Blas (apparently 3 and a half hours on local bus from PV, though not that far as crow flies), spending a couple of nights there, and birding some sites round there. There's a brilliant book I've just bought - A bird-finding guide to Mexico, by Steve Howell, lots of sites described in that area, including ones easily reached without your own car . Book pretty cheap on Amazon, and some second hand copies available, probably well worth getting, even if it just gets you to a couple of the best sites during your trip.
If we go it won't be until Jan, have a great trip :t:
Larry