I have a life list of all mammals, birds and reptiles I've photographed. This is not up-to-date, and though I try to keep it as accurate as possible I'm sure there are likely to be the odd mistakes.
It's not an easy task, but it is good when you look down it and realise you've seen more than you think, and it's fun to plan visits to fill some gaps or even to see every subspecies in a family.
but zoo animals just don't seem to count the way wild ones do.