I get this far when I hit the wall with your puzzle:
I've eliminated all but clues 1, 6, 8. How do you do a substitution at this point? I can "What If" and see that Upton cannot be the parakeet, but where's the logic approach?
EDIT: I've managed to push it a bit further. Clue 1 can be restated as "Of the parakeet and the parrot, one was purchased in Upton and the other was bought in May (aka: Quimby)".
Because of clue 8, if one of the birds is in May, the other must be April or June. Thus, Upton cannot be July and, per Clue 6, Bonita cannot be June.