Well, he was looking for spells, and parseltongue isn't a spell. And I didn't know about that piece, which still doesn't really say there aren't wild owls, just implies that the ones Muggles see flying about are almost certainly post owls.
-- Bob
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Then the horns kicked in...
...and my shoes began to squeak.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.