(adjective) Describes birds that build nests, lay eggs and raise young inside sheltered chambers or cavities, such as inside a hollow tree or in a bird house or nest box. There are two types of cavity-nesting birds: primary cavity-nesting birds excavate their own holes, such as woodpeckers that drill out chambers in suitable trees. Secondary cavity-nesting birds take advantage of natural or abandoned cavities, or in some cases will usurp them from other birds through aggressive intrusion.
The size, shape and placement of cavities for nesting will vary depending on the bird species. Some birds use a bare, empty chamber, while others line the floor or interior of the chamber with grass, twigs, wood chips, feathers, fur or other materials. Birds that are well known cavity-nesters include many woodpeckers, trogons, parrots, flycatchers and bluebirds.
Backyard birders can attract cavity-nesting birds by offering suitable nesting sites. Leaving old trees available for primary cavity nesters can be successful, and adding bird houses or nest boxes will help attract many secondary cavity nesters. Providing nesting materials for birds in spring will also encourage nesting activity nearby.
Photo – Nuttall's Woodpecker Nest © Kevin Cole
Cavity Nester (noun)