Rupp has been thinking about the relationship between humans and the natural world for more than thirty years. She moved to New York City shortly before the infamous garbage strike of 1979. Living in lower Manhattan, she watched as an alley by her apartment deepened with accumulated trash. "Rats," she said, "were everywhere."

Rupp came to the realization that she and the rats shared the urban habitat; it was because of human behavior that the rats were thriving. "We created a niche that they filled."

In the case of the ivory-billed woodpecker, the wood needed to create our human niches led to the decimation of the Southern old-growth forests that the red-capped bird needed to survive. A possible sighting in 2005 in the swampy forests of Arkansas fueled an excited frenzy that made people believe that maybe, just maybe, extinction isn't forever. But the existence of the woodpecker, not definitively seen since the 1940s, remains highly disputed.