the "former" deserve compassion and a chance to survive, which they have: they have a chance to survive. they aren't being systematically targeted for eradication, they are being left alone in nature to survive, which includes being part of the same predator/prey dynamic with the cats.
however clapper rail is probably not the best choice, since they live in marsh environments, which are not very amenable to cats. actually few birds are in much danger from cats - cell phone towers may be responsible for
more bird deaths each year (one reason i refuse to own a cell phone). a study done in golden gate park found, in fact, that the cats in the park had a net beneficial effect on bird populations. why? because while some cats are adept at preying on birds, all cats are particularly adept at preying on rodents; rats are adept at climbing up high to bird nests and eating eggs and baby birds - in golden gate park, the cat predation on rats resulted in a better survival ratio for baby birds. a large number of cats in an area does tend to affect bird some populations in a very local way, but mostly because the birds simply move, mostly not because of predation.
the cats we work with are fed - they do very little killing, which is why managed colonies are the way to go.
the biggest problem i have is the scapegoating that goes on. in the case of birds, for example, cats are often mentioned as a major factor. this is simply not true. they are a factor - a minor factor. habitat loss is responsible for over 90% of the impact on n. american bird species. various pollution impacts are about 5% more. human hunting activities, cell phone towers, airports and airplanes, and cats are each around 1%.
in n. america, we don't have and won't ever have the same problem as exists in australia - it is a unique environment. there are quite a lot of species there that evolved without a significant primary predator. the normal predator/prey scenario is not in their programming & they are disadvantaged against many of the newer, introduced predators. feral cats in n. america have to compete with some very well adapted predators for some very well adapted prey. house cats will not out compete coyotes, bobcats, mountain lions anywhere they are the primary predators, just to name the top 3. in most n. american wilderness situations, a feral housecat is as much prey as it is predator & in many it is easy prey. where they live in numbers is in urban and suburban environments - which is where managed TNR is efficient & effective.