The breeding season of the red-breasted nuthatch occurs between late April and June (4), when the male and female form a monogamous pair after a courtship display by the male, which involves flying, feeding the female, singing and erecting its crest (2) (3). In sedentary populations, the pair may remain mated for more than one season, but pair bonds in migratory populations may only be seasonal (3) (4). Aggressive chasing displays may be performed during the breeding season if non-mated males or other hole-nesting birds approach the pair’s territory (2) (3).
The female red-breasted nuthatch excavates the majority of the nest over 5 to 16 days (3), during which time she is fed by the male, who only does a small amount of excavation (2) (3). Once the cavity has been hollowed out, the female adds a base of grass, bark and pine needles, which is then topped with fur, feathers, grass and bark (2) (4). The entrance to the nest is coated with resin from conifer trees, which is occasionally applied using a twig (2) (3) (4). The resin is thought to deter competitors or predators from entering the nest (2) (3).
The female red-breasted nuthatch usually lays an average clutch of six eggs between mid-April and early May (2) (3). The eggs are white, cream or pink-white and are speckled red-brown, purple-red or brown. The eggs are incubated by the female, who is regularly fed by the male, and usually hatch after 12 to 13 days. The male and female red-breasted nuthatch both feed the young with insects for 18 to 21 days after they hatch (2) (3) (4). After this period, the young fledge the nest and remain with the adults for up to two weeks, before joining mixed-species flocks (3). The red-breasted nuthatch only raises one brood per year (2).
In winter, the diet of the red-breasted nuthatch consists mainly of seeds from coniferous and deciduous trees. During the breeding season, insects and other arthropods are also taken, including beetles, caterpillars, spiders, ants, earwigs and flies, which are also fed to nestlings (2) (3) (4). When foraging, this species walks up and down large tree branches probing into crevices for food (3), and is known to store food for times of low availability. The red-breasted nuthatch is also regularly seen around bird feeders (2) (4).