I live in a very stable community with a population of 1500 and an area of about one square mile, divided into roughly 40 blocks; neighbors get along well and properties are well-maintained. It's no secret that we like cats -- my two housemates and I have four (one of which we just had spayed and a dental problem fixed), the renter downstairs has two more, and my housemate's Mom has three more nearby.
The problem is that the neighborhood is over-run with feral cats -- most of them dropped off by irresponsible owners. Many of us can't help leaving out leftover cat food intended for the more fortunate house pets, and we've discovered several new litters this spring under nearby garages, sheds, etc.
The local ASPCA has an unwritten policy of euthanizing kittens upon arrival -- funds are limited and the demand for pets for adoption just isn't there. Once in a while, a large collection of ferals taken in -- usually by an elderly resident who lets her heart overrule her head -- simply disappears. A community of similar size about a dozen miles downriver has a similar problem -- but one of larger population (15000) just across the river doesn't -- possibly because greater numbers of fed-up neighbors are more prone to taking matters into their own hands, and/or because it's more likely to harbor a juvenile sociopath or two who prey upon harmless strays ??
As much as we hate to see innocent creatures suffering, I can't envision any kind of coordinated response to this issue above the local level; larger cities and states have bigger problems, and more vicious pests (usually of the two-legged variety) to be concerned about.