It has happened to every birder at one point or another. A great bird is seen, maybe even a lifer, and in the wake of the initial euphoria a single question is posed.
"Is it countable?"
Thankfully for those birders not interested in wading through the official rules on countability, Nick Lund of the irreverent birding blog The Birdist has created the ultimate flowchart that every birder who has ever asked that question, or even those who haven't, should have a look at.
If your quandry has not yet been settled, you'll need to head over to The Birdist for the resolution.
It's well, well worth your time.