Quackers is a duck. Sure, he may have paws and whiskers. And his quacks might sound more like...well, meows, but he lives among ducks, everyone he knows is a duck, and he's happy.
Then Quackers meets another duck who looks like him (& talks like him, too!) - but he calls himself a cat. So silly!
Quackers loves being among his new friends the cats, but he also misses his duck friends, and so he finds a way to combine the best of both worlds. Part cat, part duck, all Quackers!