Red-breasted Nuthatch (Sitta canadensis)
With stout legs, long, sharp claws, a short tail, and a long, slender bill, nuthatches are built for locomotion and feeding on tree trunks and branches. The Red-breasted Nuthatch (total length 10 cm) is a common resident of conifer forests, local breeding populations increasing with an influx of migrants in winter. Blue-gray above and warm reddish below, the species is easily recognized by the black line through each eye and pale line above it. Males have a black cap, females gray. They are also easily recognized by their ank, ank, ank calls, accelerated in response to a disturbance.
Nuthatches move freely up, down, and around on tree bark, moving in jerks like a windup toy. Upside-down is just as likely as rightside-up. Their sharp eyes are on the lookout for any sign of insect life, and there are surprising numbers of insects hiding on and in that substrate. If the bird sees the mouth of a burrow or an open crevice, it can dig in with its sharp bill and expose the prey animal, usually an insect or spider.
Most foraging is done on live conifers, more on the inner branches than the outer but including the bases of the needle clusters. Beetles make up a substantial proportion of their prey, but ants are also commonly taken. Nuthatches cache food, especially in autumn, to recover it during winter periods when foraging is difficult. They often cover cached objects with fragments of the substrate, presumably to hide them from competitors (Hairy Woodpeckers have been seen watching nuthatches and then taking their caches).
Red-breasted Nuthatches excavate their own nest cavities in dead wood or use cavities already present. The female does most of this work, but both sexes bring in material for the nest lining. This work goes on for about two weeks, then the clutch of about six eggs is laid. Both parents bring resin to their nest site, either on the bill tip or on a small piece of bark (tool use!), one of the more distinctive behaviors of this species. The resin is applied both on the outside and inside of the cavity, and it may function to reduce entry into the cavity by both competitors and predators.
Nuthatches often join mixed-species feeding flocks in the nonbreeding season, and they are among the more militant sentinel species, their loud alarm calls alerting other birds to the presence of a potential predator. Nest cavities may be used as winter roosts, an obvious adaptation to conserve heat on cold winter nights.