It is confusing...maybe because it's political.
In Defense of Animals along with one of the City Supervisors (Councilors) is pushing the City to require that the zoo only take in "rescue animals" (from naughty citizens, circuses, forest fires, whatever). The Supervisors are scheduled to decide on the measure today, but apparently there isn't enough support among them to pass it, so the backers are trying to get a delay. It sounds unlikely that it can pass.
The Zoo has contended that if passed, it would be their ruin, and the Zoo Society - which leases the zoo from the City - may walk away rather then run the zoo under such restrictions. Big donors and Board members have also said they want no part of such a facility. The AZA has threatened that it would rescind the zoo's accreditation, since the Director of the zoo would no longer be fully in control of decision making on collections.
Many believe that this is merely IDA's strategy for closing the zoo. They deny that. The City Supervisor who has pushed this so far is, apparently, considered a crank.
