I was just as disgusted when I saw that scene it the theatres, and
promptly came home and gave my fuzzies extra kisses but I do want to
point out I do not recall this actually being in the book that BuckBeak
was fed ferrets I will try and double check but to my memory the only
ferret refrence was one where Hermione turned Malfoy into a white one
and then promply turned him back.  I think the scene in the movie was
one of those scene that has caused uproar from the fans of the books and
is the reason this director who only directed this HP movie will not be
returning for the fourth movie!
 
[A later P.S.]:
I am sorry to double post but I did want make the correction to my last
post it was not hermione that turns malfoy into a ferret but Professor
Moody, also I did find the following quote on J.K Rowling's offcial
webpage www.jkrowling.com-
 
"Ron was the only one of three major characters whose surname never
changed; he has been ' weasley' from start to finish In Britain and
Ireland the weasel has a bad reputation as an unfortunate even
malevolent, animal.  However since childhood I have had a grat fondness
for the family mustelidae; not so much malignant as magligned in my
opinion." - J.K Rowling, about the weasley family
[Posted in FML issue 4715]