While they're at it, why don't they just set up a petting zoo featuring cats with feline leukemia, pigs with worms and dogs with rabies?
By the way, for all of those birds you have, I heartily recommend the NY Times. Soaks it all up real nice I hear.
If you want to know how devastating this disease is and just how stupid this zoo is being (birds with PBFD have to be quarantined for the REST OF THEIR LIVES!), here is one of many good web pages about it. If you want to have your heart broken, scroll down to the personal stories and read Laura's Story or the one about Tommy the African gray parrot: http://www.geocities.com/~calliefeather/pbfd.html