My guess is a part of the drop from the 1 million in growth, people realized that parrots / birds are not to be taken lightly, properly educating themself before they dive in, the responsibility it comes with, and time they need and should put in. Other things I would consider would be pets in general have fad like growthes... when it comes to interest into general pet areas ie dogs, cats, ferrets, sugar gliders, etc... other I would maybe guess is the avian flu at the time being in the news.. I think it was during that time which could also be attributed to it becuase of peoples lack of knowledge on the topic.

Again this is just my 2 cents...