This article at Nautilus.com about how feral cats can have a serious impact on an area's ecosystem is pretty interesting. But the headline, "Cats Are Not the Best Defenders of Ecological Health," kind of invites a little gentle mockery, because the chances are they don't care, and wouldn't even if you could get them to understand the concept.
It has always seemed cruel to me that Nature has designed cats without the ability to shrug their shoulders, because no animal on Earth could get more use out of such a gesture. Should cats ever learn to vocalize human languages, my suspicion is that "So what?" will be their first phrase.