Pygmy Nuthatch Life History

Habitat

Pygmy Nuthatches live almost exclusively in long-needled pine forests and are particularly closely associated with ponderosa pines. Look for them also in stands of other pines, including Jeffrey, Bishop, Coulter, Monterey, lodgepole, and Arizona white pine. Their typical forest habitat is open, parklike stands of older, large trees. They may occur in forests of pine mixed with oak, quaking aspen, maple, Douglas-fir, or white fir. Since they depend upon cavities in old trees (snags) for roosting and nesting, Pygmy Nuthatches are most abundant in forests that have escaped heavy logging and snag removal. They range up to 10,000 feet in the California mountains, and even higher in Mexico, where they use Montezuma, Apache, Hartweg’s, and Chihuahua pines, among others.

Food

Pygmy Nuthatches eat insects (and other invertebrates) and seeds. Flocks of Pygmy Nuthatches forage in pine trees, hopping busily up and down the trunk and out to the outermost tips of the branches. During the breeding season they eat mostly arthropods—including beetles, wasps, ants, bugs, caterpillars, and spiders—by probing cracks, scaling off loose bark, and gleaning from needle clusters and cones. In some locations their diet shifts to mostly pine seeds in the winter, while in others their winter diet resembles their breeding diet. Pygmy Nuthatches cache seeds year-round by hammering them into crevices or under flakes of bark on the tree, saving them for later. They feed infrequently on the ground and rarely capture flying insects on the wing.

Nesting

Nest Placement

Pygmy Nuthatches nest in live trees, dead trees, dead parts of live trees, and nest boxes. The male appears to take the lead in choosing a woodpecker hole or natural cavity as a nest site, usually in the trunk of a ponderosa pine or other long-needled pine, but sometimes in another conifer species or a quaking aspen.

Nest Description

Pygmy Nuthatches can excavate their own cavities, but often they just enlarge and adapt existing ones, creating irregular holes about 5–10 inches deep and 1–6 inches across. Both the male and the female, sometimes assisted by their offspring from previous years, help dig out the nest cavity and bring lining materials. In the bottom of the hole they build a nest cup of bark shreds, fine moss, grass, plant down, fur, wool, snakeskin, cocoons, and often feathers. They may also stuff similar materials in crevices within the cavity, helping to weatherproof the nest. The pair keeps lining the nest during egg-laying.

Nesting Facts

Behavior

Pygmy Nuthatches are cooperative breeders: about one third of breeding pairs get help raising their young from 1–3 male relatives. These are often the breeding pair’s own sons from previous years; they help defend the nest and feed incubating females and chicks. To deter squirrels, Pygmy Nuthatches may sway threateningly from side to side or even cover the entrance with their bodies to make it less visible. In winter, multiple family groups join up to form large, chattering, highly social flocks that range over a foraging territory. These flocks also forage with other species including warblers, chickadees, bushtits, kinglets, woodpeckers, and juncos. In cold weather they seek out well-insulated cavities to spend the night. Pairs roost together and juveniles roost with their parents as part of larger groups. Sometimes more than 150 individuals sleep in a single tree, stacked up in squares, triangles, diamonds, oblongs, or tiers of birds. They use controlled hypothermia in addition to group roosting to withstand cold winter nights, a combination of strategies used by only one other North American bird species, the Vaux's Swift.

Conservation

Pygmy Nuthatches' tendency to move around in large groups makes it difficult to monitor population trends with standardized surveys. Within their patchy range, populations appear to have stayed relatively stable from 1966 to 2014, though there is some indication of populations experiencing a small decrease every year according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 3.3 million and rates the species an 11 out of 20 on the Continental Concern Score, indicating it is a species of low conservation concern. Throughout the twentieth century, logging, grazing, and fire suppression converted many ponderosa pine forests—previously parklike woodlands with large, tall trees favored by nuthatches—into mosaics of differently aged trees and dense thickets. The Pygmy Nuthatch population has presumably declined as a result, since the nuthatches rely on mature pines and standing dead trees for suitable nest sites and foraging habitat. Forest managers can help Pygmy Nuthatches in mature pine forests by allowing dead trees to remain standing—recommendations suggest that at least 7–12 large snags (at least 19 inches in diameter) should be left standing per hectare (2.5 acres) of forest. People can help increase Pygmy Nuthatch abundance by installing nest boxes in disturbed forest, which can double the number of breeding pairs in an area. Though they’re useful for nesting during the breeding season, boxes are rarely used for year-round roosting.

Credits

Kingery, Hugh E. and Cameron K. Ghalambor. (2001). Pygmy Nuthatch (Sitta pygmaea), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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