A chum in Vermont sent me this anonymous quotation: "A cat can do little but a clowder of cats can work great havoc." That sent me running to my dictionary. I have been amused by the great variety of collective nouns in English for a long while, but never before have I heard/read that "clowder" describes a number of cats, house cats, domestic cats. A "kyndyll" or "kindle" of kittens ... yes ... but never a clowder, once they are all grown up.