Nuthatches are small, active birds known for foraging head-first down tree trunks, a unique behavior that distinguishes them from most other avian species. Found across North America and Eurasia, they inhabit wooded areas, searching for insects and seeds hidden in bark crevices. Their nesting habits are as distinctive as their foraging style, revolving around the selection and modification of existing tree cavities. Understanding their nest location, construction materials, and species-specific behaviors helps identify a nuthatch’s home.
Preferred Nest Locations and Cavity Selection
Nuthatches primarily select natural tree cavities, abandoned woodpecker holes, or human-provided nest boxes. They prefer snags (standing dead trees) or trees with decaying wood because these materials allow for easier excavation or modification of the cavity’s interior. Nest height varies widely depending on the species and habitat, ranging from close to the ground in stumps or fence posts to as high as 88 feet in tall pines.
The physical dimensions of the cavity entrance are a defining factor in nest selection, as a smaller, restrictive opening offers protection from larger predators. For instance, the entrance hole to a White-breasted Nuthatch nest cavity is often around 1.25 inches in diameter, a size that excludes most larger cavity competitors. Brown-headed Nuthatches prefer an entrance diameter between 1 and 1.5 inches, with the cavity typically measuring between five and ten inches deep.
Interior Construction and Lining Materials
Once a suitable cavity is secured, the female nuthatch begins interior construction, creating a loose, structureless collection of materials. The foundation is built from coarser items, such as bark flakes, shredded bark strips, small twigs, and sometimes lumps of dirt or dried earth pellets. The volume of material used can be substantial; one observed nest contained over 11,000 bark fragments.
Building upon this coarse base, the bird creates a soft, cup-shaped lining for the eggs. This inner cup is constructed from finer, softer materials to insulate and cushion the clutch. Common lining materials include fine grasses, hair, animal fur, feathers, rootlets, and pine seed wings. This layering ensures a secure and comfortable environment for the developing eggs and nestlings.
Species-Specific Nesting Behaviors
Nesting behaviors vary significantly between nuthatch species, providing distinct clues for identification. The Red-breasted Nuthatch exhibits a unique behavior of plastering the area around the nest entrance with tree pitch or resin. Both the male and female carry globules of this sticky material to the hole, which is thought to deter predators and competing birds.
The Brown-headed Nuthatch, found in southeastern pine forests, often uses plant material, leaves, and grasses to fill in crevices or waterproof their nest cavity, particularly when using artificial nest boxes. This species practices cooperative breeding, where young males from a previous brood may act as “helpers” to assist the breeding pair in feeding the incubating female and the nestlings.
The White-breasted Nuthatch generally utilizes existing, unlined cavities and does not typically engage in extensive entrance modification. They have been observed sweeping the outside and inside of their nest hole with crushed insects, a behavior that may use the insect’s chemical secretions to repel potential predators. The Pygmy Nuthatch, which also uses cooperative breeding, is known for its highly social behavior, often roosting communally in cavities with up to 150 individuals during cold winter nights to conserve heat.
Nuthatch Eggs and Nestling Appearance
Nuthatch eggs are generally creamy white or pinkish-white and feature fine speckling or blotches. These markings typically consist of reddish-brown, gray, or lilac spots, often concentrated more densely toward the wider end of the egg. Most North American species lay a clutch size ranging between five and nine eggs.
The incubation period, carried out primarily by the female, lasts approximately 12 to 14 days, during which the male may bring food to his mate. Upon hatching, the nestlings are altricial, meaning they are helpless, naked, or covered with sparse downy feathers. The young remain in the nest for about two to three weeks before they are ready to fledge.