Forests are more than just a collection of trees. A forest is a community that includes the soil, water, plants and animals found there. Forests are also divided into distinct layers. The top layer is called the canopy. The canopy provides nesting sites for many birds, such as scarlet tanagers and cerulean warblers.
Squirrels also nest in the canopy.
The next layer down, the understory, is made of smaller trees and tall shrubs. This is the layer that we often see when looking up into the forest. Insects, birds and mammals occupy this layer, foraging for food and building homes. Below the understory is the shrub layer dominated by shrubs and tree seedlings. Many birds, such as the wood thrush, nest here and insects are very abundant.