There are pros and cons for why INTPs would do okay in birdwatching.
We're naturally introverted, so we wouldn't get really boring. We're fairly intelligent, and would probably do well identifying and spotting birds.
On the other side, it's another six hours away from our computers. We also love thinking, and the forest is a peaceful place to think. But we'd get captured in our thoughts, daze off, and our weak Se function wouldn't snap us back.
Of course, if an INTP was looking stimulate their Se function then it might be worthwhile.