In New Zealand, there is a parrot that is so stupid, it has a) forgotten it can fly and b) doesn't know what the opposite sex looks like until they happen across each other at mating time. When this happens the male forgets it can fly and spends all its time hopping round on the ground waiting for the female who is in a tree. The female sits there thinking - 'here I am, come and get me. I'd come down to you, but I can't fly'.

Needless to say, they are quite rare.

LTS