I'll be curious to see what others say too. I am a part-time birder but I have to say that STJ is the place for marine life, not birds. There are a ton of wonderful pelicans, brown boobies, banana quits, but to be honest, in my travels there I haven't seen too many birds. Frog sounds galore at night and fabulous marine life but I don't think there are that many birds -but maybe a true birder will set me straight! No swampy areas I don't think like say the Everglades so I can't imagine a specific sanctuary, just the usual shorelines.

There are many field guides to birds of the West Indies. Lots of interesting birds around, also. The Park Service does a bird count every year in, maybe January? You could get more information from them.

I remember reading that the Francis Bay trail is an excellent spot for bird watching. I haven't walked it, so I don't know for sure. Good luck!