Hungry Chicks is divided into four locations, Birdyland Forest, Chirpy Desert, Tweety Island and Urban Jungle (added in of Version 1.1). and each one offers a different background for its 12 levels. In the foreground are your parent bird(s), the nest of chicks, the worms to feed them and the collection of obstacles scattered across each level to make it hard to feed all of your chicks and beat the level.
The four locations have a different background tune accompanying them. Birdyland Forest has a folksy sound to it that seems to use a lot of flutes, while the Tweety Island has a predictably island sound to it. Urban Jungle has a percussion-heavy tune with the occasional monkey sounds. As for the second world, Chirpy Desert, where I would have suspected something with a western theme, Hungry Chicks decides to go for a more Middle Eastern sound.