Nature is a major motif in Willodeen. The woods and waters near Perchance make up myriad ecosystems, and each of those works in its own way to keep the village thriving. The relationship between the screechers, blue willows, and hummingbears is the most obvious ecosystem, but there are other environmental factors alluded to throughout the book, such as the effects of people on nature. It’s mentioned that before the events of the story, the world had been changing for years. More disasters struck, and the dry earth led to fires. The exact causes of these disasters are not explored, but they are likely due to different parts of nature being unbalanced, possibly because of human interference. Most of the people in Willodeen’s village don’t consider themselves part of nature, which mirrors how many people in the real world see themselves outside the balances that keep nature thriving.

Applegate made up several species of plants and animals for Willodeen, each of which represents a real species or group of species from Earth. Screechers are based on small predator animals, such as coyotes. While screechers don’t appear to be a threat to small, domesticated animals like dogs or cats, they are viewed as a nuisance and something to be gotten rid of.