A variety of living and dead trees, deciduous as well as coniferous, are used. Although Red-breasted Nuthatches are characteristic inhabitants of coniferous forests, they also forage in deciduous trees and sometimes nest at a considerable distance from conifers. The nest height varies from 2 to 120 feet, most nests being found about 15 feet above ground. The cavity is about eight inches in depth and is lined with soft material such as shredded bark, grasses, rootlets and, often, hair. The cavity entrance is invariably smeared with spruce or pine pitch brought by both male and female in their bills, often from some distance.
Pitch is carried to the nest from the beginning of nest building until the young have left the nest.
This behaviour may be related to the habits of several eastern hemisphere nuthatch species which use mud to reduce the size of the entrance to their nest cavity. Certain species even construct an entire nest of mud, with a tubular, spout-like entrance. The large mud nest of the Rock Nuthatch may weigh up to 950 times the weight of one bird. The female lays from four to seven eggs and incubation takes 12 days. The young are fed a variety of insects and other invertebrates.