Decades of "bleaching" events and diseases have been devastating to coral reefs surrounding national parks in the Caribbean and off South Florida, so much so that the losses are akin to "losing the Redwoods."

A worm with a lot of body English might be good for fishing, but when it's an uninvited pest introduced to the forest duff of Great Smoky Mountains National Park, well, it's just bad news.

It seemed like a good idea at the time.

It's a brilliant fall morning and instead of being holed up in my stuffy office cube, I'm out stalking grizzly bears. I've come to Yellowstone National Park to learn more about the wildlife here, particularly its two top predators: grizzlies and wolves.