Other than the woodpeckers, red-breasted nuthatches (Sitta canadensis) are one of the few avian species to excavate their own nests. Both the male and female red-breasted nuthatch work together to dig a nest cavity, although the female does more of the work. Excavating a tree hole is difficult for these little birds, a task often taking several weeks to complete. The female chooses the site, if possible in a tree with soft wood or in a dead or partially dead tree in order to make the job easier. If available, an existing nest hole may be used. Sometimes a male without a mate will begin to excavate a hole in an attempt to attract a female. I am watching what I believe is the beginning of a nuthatch hole at Ash Creek (Lassen County CA). After a rapid start the hole now appears to be abandoned. I wonder if this was an aborted attempt by a male nuthatch to attract a female?
The female red-breasted nuthatch builds a nest out of grass, pine needles, and bark strips, lining it with fur, feathers, fine grasses or shredded bark. The nuthatches carry bits of conifer resin in their beaks or on the end of a piece of bark to the nest hole and apply the resin around the nest hole entrance. The exact reason for surrounding the hole with resin is unknown, but is assumed to help keep out predators and insects. Using a bit of bark as an applicator sure resembles tool use to me.
Two to eight creamy, white or pinkish eggs with red-brown speckles are incubated for 12 or 13 days. The nestlings, born naked and helpless, remain in the nest 18 to 21 days before fledging. Red-breasted nuthatches are aggressive during the breeding season and protective 0f their broods.
This red-breasted nuthatch nest is on the shore of Manzanita Lake in Lassen Volcanic National Park (Shasta County CA). More information on red-breasted nuthatches can be found in my previous post (“Red-breasted Nuthatch” – 06-02-14).