A few years ago, we climbed a mountain overlooking Lake George to watch the sunset. We were wandering around the summit admiring the views when a piercing shriek interrupted the calm. It came again and again. We soon located the source: a peregrine falcon perched on a nearby rock, giving us the business. Once close to extinction, and still on the endangered species list, peregrine falcon populations have rebounded thanks to a ban on the chemical DDT (which thinned bird shells) and "hacking" programs that take hatchlings from other locations, place them in artificial nest sites and care for them until they're ready to be independent.