yes, palawan is indeed a great place, for birding as well as snorkelling and diving. i went there in feb of 07 and spent a week at el nido. i did mainly snorkelling and didn't went birding. but birds are everywhere around the bungalow including swiftlets, sunbirds, mynas, cuckatoos and egrets. and i was lucky enough to have seen the palawan hornbill. they were right above our heads when we're having poolside breakfast. its definitely a memorable experience and a place to visit again. maybe i should try canoeing underground as you've mentioned when i do so.