There will be of course a lot of waterbirds. Around your hotel you'll see also White-crowned pigeon, Greater Ant. grackle, palmchats, Antillean mango, Vervain Hummingbird, Hispaniolan lizard cuckoo, Hispaniolan woodpecker, Black-crowned palm tanager, Hisp. Oriole, palm swift, . If you take a cable car ride up to Isabela mountain (south of Puerto Plata) you'll find todies, Hisp. Emerald. If you take to Cabarete you'll easily see Flat-billed vireo.
Enjoy!
My wife and I are just back from DR. Marvellous place! Not a full-on birding trip - my wife doesn't bird.
I saw most of the above around our hotel (not Vervain Hummingbird or oriole!) plus Zenaida Dove, Village Weaver, Grey Kingbird, Red-legged Thrush, Shiny Cowbird, Ovenbird, Yellowthroat, Louisiana Waterthrush, West Indian Whistling Duck, Nutmeg Mannikin among others.
Ok the country is very poor but we found the Dominicans the warmest people we've met on our travels and I can recommend trips out to the capital Santo Domingo and a visit to the countryside (by Outback Safaris) to see something of the real DR.
Other points: we visited Pico Isabel de Torres by cable car which was great but unfortunately around midday when birds were difficult to find. It was part of a Puerto Plata tour so it was a very brief visit (1 hr) and apart from the Turkey Vultures gathering on the radio mast I only saw 1 other bird - a brief unidentifiable hummingbird. My tip would be to do it yourself and go early.
Best times to bird: first thing in the morning and midafternoon to sunset. The rest of the time chill out on the beach or by the pool but keep your bins handy as there's still some bird activity through the day.
If your getting a drink from the poolside bar etc. get something sweet too for the Bananquits. We got some down for photos using a cup of 7up!
In a perfect world everyone's partner would bird too and then we could all blitz the island and see all the endemics etc, but if like me you of necessity must make compromises then I can recommend the DR because of it's well established tourist infrastructure, welcoming people, and fantastic suite of great birds.