The World of Cavity-Nesting Birds

When most people think of bird nests, they usually envision a cluster of twigs and branches with a few leaves entwined. The typical bird nest isn’t home to every bird, however. Cavity-nesting birds are one type of bird that you won’t see nesting on a branch in the trees.

What is a Cavity-Nesting Bird?

Cavity-nesting birds are birds that, like every bird, build nests, lay eggs, and raise their young. But, they do so within natural chambers such as trees, rocks, cliffs, dirt mounds, and even chimneys. Unlike most birds, cavity-nesting birds don’t create elaborate nests from raw materials. Instead, they shelter in crevices that they find or create. Ornithologists have discovered there are two types of cavity-nesting birds.

See also: A Bird Nest is an Engineering Marvel

Two Type of Cavity-Nesting Birds

Primary cavity-nesting birds are birds that unearth their own burrows or holes. This can take from days to weeks depending on the bird’s nesting needs. Secondary cavity-nesting birds do not dig their own holes or burrows, but rely on the deserted ones of other birds. Sometimes a bird will take over a hole in an aggressive act, forcing the other bird out of its nest. Like a house in move in condition, they make no major changes to the cavity.

85 North American species of birds nest in cavities. That's 13% of all breeding species on the continent. While Ornithologists and researchers don’t point to a specific reason why some species are cavity-nesters, their unique bills, made for digging in tree barks, may be one answer. Woodpeckers, nuthatches, and wrens are all cavity-nesting birds. They each have long, sharply pointed bills suitable for excavation work.

See also: How to Attract Woodpeckers to Your Backyard

Pileated Woodpeckers

Typical Cavities Birds Use

Nesting cavities are as diverse as bird nests in trees. They vary according to the bird’s species and its nesting needs. The size, shape, and where they place the nest vary accordingly. Some of the chambers a cavity-nesting bird might use include:

• Stone walls and natural cliffs
• Rock crevices
• Holes in logs or tree stumps
• Holes in a dead or decaying tree
• Burrows in dirt mounds
• Burrows in soft riverbanks and dunes
• Exposed chimneys and pipes

Dangers Cavity-Nesting Birds Face

Like other nesting birds, cavity-nesting birds face the dangers of predators. Predators can access their nests inside trees, rock crevices, or stone walls, catching them and their young inside with no way to escape. Some species have their own way of lowering the chance of a predator getting into their nest.

It may be small, but the red-breasted nuthatch is mighty in its determination to protect its young. This species smears sap around the entrance holes of its nest. The white-breasted nuthatch, the larger of the two species, rubs foul smelling insects around the entrance hole of its nest. The red-cockaded woodpecker drills wells above and below nesting holes that allows tree resin to flow, preventing snakes from reaching its nest.

Common Cavity-Nesting Birds

While there are 85 species of birds that are classified as cavity-nesting birds, only some are commonly spotted in residential areas.

Woodpeckers are the stars of the cavity-nester world. Woodpeckers don't just create holes for their own nests–their cavities are used by other species that aren’t suited to excavate their own. For this reason, many cavity-nesting birds, especially secondary cavity-nesting birds, rely on the excavation work of woodpeckers.

In most parts of the United States, you’re bound to see the cavity-nesting chickadee. The wren is another cavity nester. If you live in the east, you're likely to spot the Carolina wren. House wrens are cavity-nesting birds that can be seen throughout the country. The bluebird—of Eastern, Western or mountain subspecies—is also cavity-nesting bird.

See also: Attracting Black-Capped Chickadees

Nesting Chickadee

Attracting Cavity-Nesting Birds to Your Backyard

You don’t have to comb the forests or woodlands in order to spot species of birds that nest in cavities. Backyard birders can attract cavity-nesting birds to their backyard by offering nesting sites that suit these birds’ nesting needs. Landscaping your backyard to make it bird friendly, especially for cavity-nesters, means forgetting about a perfectly trimmed and groomed yard. Leaving grass a bit longer and ignoring leaf piles will attract birds to your backyard by offering them food sources, nesting materials, and shelter. What you are doing, in fact, is recreating the look of a bird’s natural habitat.

Let your flower garden go to seed and birds will enjoy a nutritious diet while you save on birdseed. Using organic fertilizers and natural bug repellants will ensure bird safety as well as a steady diet of insects. Offering water features such as bird baths and drips is another way to attract these cavity-nesters to your backyard.

Keeping Cavity-Nesting Birds Safe in Your Backyard

Providing the right nesting sites along with food and water sources is important not only in attracting cavity-nesting birds, but in ensuring they choose safe nesting sites. When you are birdwatching, keep an eye on birds that end up nesting in unsafe sites such as chimneys, pipes, dryer vents, or central air conditioning units. Should this happen, it is best to call in a professional such as a local rescue group or Audubon Society chapter to remove the bird safely.

Cavity-nesting birds offer an exciting new opportunity to backyard birdwatchers. These fascinating birds add another dimension to your birdwatching as they nest and raise families in a habitat you helped to create.