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.

It looks somewhat like a dusting of confectioner's sugar, but the white coating that is showing up on more and more noses and wings of bats is the signature of a dire fungal disease that threatens to decimate bat colonies across the country.

Lead bullets in carcasses and gut piles pose lethal poisoning hazards to carrion feeders. Among the creatures most at risk are the endangered California condors that frequent Grand Canyon National Park and other areas of Arizona and Utah.

Winter is one of the best times to enjoy our parks! With majestic, snow-capped mountains and ice-covered lakes, winter provides scenic splendors with an array of exciting activities. While visitation peaks in the summer, national parks receive millions of visitors throughout the winter months, who come to enjoy such activities as skiing, snowshoeing, camping, and hiking in the backcountry, and attending ranger-led programs.