In the smaller canyons, there are no coyotes left because they require large intact areas for their home range. Without coyotes to keep them in check, possums, feral cats, and red foxes explode in population size, resulting in unnaturally high levels of predation on native birds and small mammals. At the same time, no one wants to see an explosion of rats and mice either, which these middle-predators, albeit exotic, help to control. The bottom line is that there are no easy answers. As with many other exotics, the red fox is now part of delicate ecosystems, many of which have had the balance already tilted by human meddling on a grand scale.
Humans are, of course, the ultimate exotic species.
Our chainsaws and pesticides, fences and fossil-fuel engines do far more damage than any other species. Our intrusions into the wild domains causes us to view natives like coyotes as pests that must be eliminated, or larger and stronger animals like bears as threats to our safety. In the March 26th election, Californians will once more vote on mountain lion hunting, with supporters pointing to the two people killed last year as just cause. But although almost all ecosystem invasions are caused by humans, we're sometimes innocent confederates. The native cowbird originally followed herds of buffalo and later cows, seeking worms and grubs from freshly disturbed soil.