Formerly known as the Canada Nuthatch or the Red-bellied Nuthatch, the Red-breasted Nuthatch is a common resident of North America's boreal forests. Its characteristic “tinhorn” yank yank call can be heard year-round in coniferous forests from the Pacific Coast of British Columbia to the Atlantic Coast of Nova Scotia, extending southward into the mountains of the American Southwest and the southern Appalachians in the East. The Red-breasted Nuthatch differs from North America's 3 other nuthatches in its preference for forests that have a strong fir (Abies spp., Pseudotsuga spp.) and spruce (Picea spp.) component. In contrast, the Pygmy (Sitta pygmaea) and Brown-headed (S. pusilla) nuthatches prefer more southerly forests of pure pine, and the White-breasted Nuthatch (S. carolinensis) prefers deciduous forests. Despite the broad geographic range of the Red-breasted Nuthatch, no subspecies are recognized in North America, although it is considered the only New World representative of a larger super-species that may have been more widely distributed throughout the Holarctic. In recent times, its breeding range has expanded southward, particularly in the southeastern United States and in southern Canada, where conifer plantations have increased suitable habitat.
The Red-breasted Nuthatch exhibits characteristic “nuthatch” behaviors, such as climbing head-down on the trunk of trees probing for insects, extracting and caching seeds in the winter, and readily joining other species in nonbreeding foraging flocks. It is unique among North American nuthatches, however, as the only species to undergo regular irruptive movements that appear to be primarily driven by a shortage of winter food on the breeding grounds. During irruption years, large numbers of individuals often invade uncharacteristic habitats as far south as the Gulf Coast of Louisiana and the desert washes of northern Mexico. With its propensity for long-distance movements, the Red-breasted Nuthatch is the only North American nuthatch to have crossed the Atlantic to Europe as a vagrant.
Breeding birds typically excavate their own nest cavities in tree snags and only rarely use existing cavities or nest boxes. One distinguishing feature of nests is the large amount of conifer resin that parents collect from live trees and smear around the entrance during the incubation and nestling periods in what may be a strategy to deter predators and competitors from entering the cavity. In winter, Red-breasted Nuthatches are often associated with other resident species in mixed-species foraging flocks, and they are common visitors to bird feeders.
Despite the abundance of the Red-breasted Nuthatch throughout North America, its irruptive movements and aversion to nest boxes make certain aspects of the species' biology difficult to study. However, some highly informative studies are Ball's ( Ball 1947 ) description of irruptive movements and behavior over a 10-year period at the Gaspé Peninsula in Canada, and Kilham's ( Kilham 1973c ) detailed account of reproductive behavior in captive individuals.