Reviewed by: John C. Robinson, USDA Forest Service, 1323 Club
Drive, Vallejo, CA 94592 (707)-562-8929.
SPECIES: Red-breasted Nuthatch (Sitta canadensis)
Despite its wide-ranging distribution, no subspecies of Red-breasted Nuthatch are currently recognized. Although Burleigh (1960) described a subspecies of Red-breasted Nuthatch for populations mainly west of the Rocky Mountains (from southeast Alaska to southern Arizona), those findings could not be corroborated (Ghalambor and Martin 1999).
No special status. Protected under the Migratory Bird Treaty Act.
RANGE IN CALIFORNIA
1. Historical References
Grinnell and Miller (1944) indicated the Red-breasted Nuthatch was a common resident within its breeding range, which was described as the higher parts of northern California and continuously along the southern Sierra Nevada and scattered on the highest mountains to the southern part of the State down to San Jacinto Mountains in Riverside County. To the north, the breeding range extended to Oregon via the Warner Mountains in Modoc County and the Siskiyou Mountains in western Siskiyou County. Grinnell and Miller (1944) described its habitat as coniferous forest, mainly of the Canadian life-zone; but also “ represented meagerly in transition and, rarely in Hudsonian”. White fir and red fir were considered the most frequently used trees. Breeding was documented to typically occur between 2500 feet (western Trinity Co.) up to 8800 feet (Yosemite National Park); up to 10,000 feet in southern Sierra Nevada (Olancha Peak).
2. Current Breeding Distribution
The Red-breasted Nuthatch is a fairly common resident in conifer forests
from low to high elevations throughout the state. It is a summer
resident in the Sierra Nevada, Cascades, Trinity Mts. and other ranges
in ponderosa pine, mixed conifer, red fir, lodgepole pine, Jeffrey pine,
eastside pine, and coastal conifer habitats. It is sporadically dispersed
to lowlands in winter where it sometimes forages on deciduous trees.
An irregular fall transient in desert regions, varying from common to absent.
A sporadic fall transient and winter visitant to interior Great Basin and
coastal California (California Dept. Fish and Game 1990).
Ghalambor and Martin (1999) summarize the current California distribution for the Red-breasted Nuthatch as follows:
Breeding Range Winter Range
Breeds from Oregon border south through Coast Ranges (excluding immediate coast) to southern Mendocino and southern Lake Counties, and locally from Sonoma County south to Santa Clara and Santa Cruz Counties; from Warner Mountains and Cascades south through Sierra Nevada to southern Tulare County; in White Mountains; and mountains of the Modoc Plateau. Also breeds in area of Mt. Pinos and Mt. Able (southern Kern County, Ventura County); at Big Pine Mountain and Figuero Mountain in Santa Barbara County; at Clark Mountain in San Bernardino County; in the San Gabriel, San Bernardino, and San Jacinto Mountains; and sparingly in mountains of San Diego County. Largely resident, wintering mostly within breeding range, with possible exception of high-elevation montane populations. Northern California is included among sites representing the highest wintering densities of Red-breasted Nuthatches in the western U.S. Less numerous in drier sagebrush and desert regions; reaches most southern deserts only in exceptional flight or irruptive years.
1. Average Territory Size
California Dept. of Fish and Game (Zeiner et al. 1990) documents Red-breasted Nuthatch density for Sierran Nevada coniferous forests ranged from 3.7-5.1 pairs per 40 hectare (100 acres). In general, however, habitat plays a large role in determining actual size of breeding territory (Ghalambor and Martin 1999), with some sites in hemlock (Tsuga) forests as small as 0.2 ha. while other sites in subalpine forests may be as large as 10 ha. The density of breeding birds is also influenced by the number of snags suitable for nesting. Individuals that do not migrate show some tendency to maintain winter territories, whereas birds that migrate to locations south of the breeding grounds do not appear to exhibit this behavior (Ibid. 1999).
2. Time of Occurrence and Seasonal Movements
a. Arrival Date on Breeding Grounds/Spring Migration Period
Breeds from early April to August, peaking in early June. According to Bent (1964, courtship may begin as early as March (Ellsworth, Maine), but is not common until April or May. Ghalambor and Martin (1999) state that non-resident birds initiate courtship upon returning to their breeding grounds, usually in March or April, but some birds may not arrive until May; and that resident individuals (i.e., birds that do not migrate) may begin courtship much earlier than that.
b. Departure From Breeding Grounds/Fall Migration Period
Primarily resident in California, but may disperse irregularly to lower elevations in fall and winter (Grinnell and Miller 1944, Zeiner et al. 1990). Although more birds are typically seen in the fall than in the spring, true southward migrations of Red-breasted Nuthatches in the western United States are not as extensive as they are in the east (Ghalambor and Martin 1999). The migration may begin as early as August, with numbers peaking during the month of October.
3. Nest Type
The Red-breasted Nuthatch usually excavates a cavity in a rotten branch or stump of a dead tree, occasionally nests in deserted woodpecker hole, and has been known to breed in artificial nest boxes (Bent 1964, Grinnell and Miller 1944, Ehrlich et al. 1988, Matthysen 1998). Nest excavation may be initiated several times before a nest site is selected (Matthysen 1998). Nest excavation typically lasts from 3 to 9 days, but has been reported to last up to 2 months (Ibid).
The dimensions of the nest hole have been reported to be just over 1 inch by 1 inch (plus or minus ½ inch). The Red-breasted Nuthatch has been reported to consistently smear pitch all around the outside of the nest-hole throughout the nesting season until young have fledged. It is believed that this behavior serves to defend the nest from small rodents or insects (Matthysen 1998). Within the cavity, the open-type nest consists of a bed of soft materials composed of bark shreds, soft grasses, pine needles and roots; and the inside of the nest is often lined with fur, feathers, hair, dry leaves, grass, and shredded bark (Bent 1964, Ehrlich et al. 1988, Ghalambor and Martin 1999).
4. Foraging Strategy
The Red-breasted Nuthatch is insectivorous feeding on beetles, hymenoptera, spiders, and wood-boring beetles. They also feed on conifer seeds, on trunks of dead conifers, or in dead parts of living trees. May also forage on cottonwood and black oak at lower altitudes (Grinnell and Miller 1944). Typically the Red-breasted Nuthatch forages over the trunks and branches of trees in true “nuthatch fashion” to feed on insects, but will also fly into the air and “flycatch” to capture flying insects. Hendricks (1995) reported that Red-breasted Nuthatches may be important in the seed dispersal and germination of forest trees, based on his observations of seed caching behavior of Red-breasted Nuthatches in Montana. Food caching behavior in this species is apparently more common and widespread than previously thought. Reliance on cached seeds seems to be greater in northerly populations (Ghalambor and Martin 1999).
On the west slope of the Sierra Nevada, Adams and Morrison (1993) found
seasonal differences in foraging behavior based on relative arthropod abundance.
Red-breasted nuthatches partition their use of tree species for foraging
evenly across all seasons, probably due to their use of seeds in the winter.
In winter, Red-breasted Nuthatches forage more on trunks of trees than
on twigs or branches. This is related to availability of more bark-dwellers
in the winter versus the availability of foliage dwellers in the summer.
Percent basal area of white fir (Abies concolor) was strongly correlated
with nuthatch foraging throughout the seasons. High intensity of
use for foraging was highly correlated with stands that had complex stand
structure, higher tree basal area, and diverse tree species composition.
Nuthatches used California black oak (Quercus velutina) more in May-June
that in September–October. Incense-cedar (Libocedrus decurrens)
was used heavily during all seasons.
In general, diet consists mostly of arthropods throughout the breeding season, and is supplemented by conifer seeds during the non-breeding season. Young birds in the nest are fed a diet made up exclusively of arthropods. This species is often found frequenting bird feeders (Ghalambor and Martin 1999).
a. Courtship Displays
Matthysen (1998) reports that courtship displays have not been well described for the Red-breasted Nuthatch, perhaps because their courtship displays seem to be short in duration. Prior to copulation, the male has his head and tail raised, wings dropped, back feathers fluffed up while it sways its body from side to side (pendulum-like) with his back turned to the female and sings (Matthysen 1998, Ehrlich et al. 1988). Pendulum displays were also noted in singing males and in females during pair bond formation in mid-winter or when courtship feeding occurred. Bent (1964) reported that little information about courtship for the Red-breasted Nuthatch was known. However, he reported a courtship observation from Sudbury, Mass which described how a male nuthatch “zigzagged through the bare limbs of a large old apple tree” and was later joined in this behavior by a female. Five specific types of courtship display are summarized by Ghalambor and Martin (1999) and include behaviors involving singing, flying, or feeding.
b. Threat Displays
Matthysen (1998) describes threat displays of the Red-breasted Nuthatch to be similar to other species of nuthatches, with the primary threat display as a posture with drooping wings and erect tail, but the Red-breasted Nuthatch has a raised crest feathers that appears to be unique among nuthatches. The head may also be lowered and the bill pointed downward. In relation to threats to other bird species, the Red-breasted Nuthatch’s wings are lifted and spread and the tail is fanned, sometimes with a pendulum-like movement. Ghalambor and Martin (1999), in a summary of agonistic behavior in this species, report that the threat displays used by males are not unlike the displays used for courtship of females; generally, agonistic behavior in this species includes both an aggressive display and a combat display.
6. Mating System
The mating system for the Red-breasted Nuthatch has been described as “socially monogamous” (Ghalambor and Martin 1999). The pair bond is established on the breeding grounds. In some instances, pairs may stay together on the breeding territory throughout the year if there is an adequate supply of food resources during the winter. Indeed, winter territories are defended by resident Red-breasted Nuthatch pairs (Ehrlich, et al. 1988, Ghalambor and Martin 1999).
7. Clutch Size
Usually 5-6 eggs, but sometimes 4 to 7 eggs, occasionally may lay as many as 8 (Bent 1934, Ehrlich, et al. 1988, Ghalambor and Martin 1999).
8. Incubating Sex (Female/Male)
The brood patch is well developed only in the female, whereas males may develop a partial brood patch. Available evidence indicates that only the female incubates the eggs, although the male may roost in the nest cavity during the incubation period (Ghalambor and Martin 1999).
9. Incubation Period
Available evidence indicates that the incubation period lasts form 12-13 days (Ghalambor and Martin 1999).
10. Nestling Period
Young Red-breasted Nuthatches usually leave the nest between 18 and 21 days after hatching. Thereafter, they may continue to harbor a close relationship with the parent birds for another two weeks (Ghalambor and Martin 1999).
11. Development at Hatching
Young are considered altricial and nidicolous at the time of hatching (Ghalambor and Martin 1999).
12. Number of Broods
The Red-breasted Nuthatch only raises one brood of young per year; only two cases of double-brooding have been reported – one in the wild and one in captivity (Ghalambor and Martin 1999).
13. Who Tends Young
Brooding is only done by the female, although the male is known to roost overnight inside of the nest cavity during the brooding period. Both sexes feed the young (Ghalambor and Martin 1999).
Overview of Breeding Habitat
Several studies support the conclusion that the Red-breasted Nuthatch
show a preference for breeding in mature to late-successional forests where
nesting density has been shown to be positively correlated with the density
of old, diseased and dead trees. Nuthatches are considered to be
weak excavators as compared to most woodpeckers which are strong excavators.
Generally, the weak excavating Red-breasted Nuthatch tends to nest in old
and dead trees which have a high level of wood decay that are characteristically
found in old forests. Dead and diseased trees required for nesting
may generally be lacking in managed and younger forests where large, old
or dead and diseased trees have been removed through timber harvest or
other disturbance events.
In British Columbia, one study found that Douglas fir (Pseudotsuga taxifolia) was preferred for nesting followed by western larch (Larix occidentalis) and paper birch (Betula papyrifera) (Steeger and Hitchcock 1998). Dead lodgepole pine (Pinus contorta) trees which had been infected by mountain pine beetle were avoided for nesting. The Red-breasted Nuthatch preferred to excavate cavities in dead trees with broken tops infected by Armillaria root disease and stem rot. The trees selected for nesting were taller and larger than randomly selected trees. Another study in British Columbia (Harestad and Dagmar 1989) found that Red-breasted Nuthatches did not nest in Douglas fir relative to their availability, attributing this due its pattern of decay “from the outside in”. However, in western Oregon, Red-breasted Nuthatches used Douglas fir for nesting relative to their availability, probably due to the lack of dead trees of other species.
1. Nest Site
a. Nest Substrate2. Vegetation Surrounding the Nest
Primarily dead trees, rarely nests in live trees. Trees selected for nesting include aspen (Populus), Douglas fir (Pseudotsuga taxifolia), white fir (Abies concolor), paper birch, and western larch (Ghalambor and Martin 1999). One study in British Columbia found that Red-breasted Nuthatches nested in dead trees 95% of the time (Steeger and Hitchcock 1998). Nuthatches preferred to nest in dead trees with broken tops where both decayed sapwood and decayed heartwood were present. Trees infected with Armillaria root disease and dwarf mistletoe may also be favored. Nuthatches in British Columbia also selected trees that were taller and had larger diameters compared to trees that were not used for nesting (41.0 cm +/- 2.61 for nest trees, 28.7 cm +/- 0.76 for non-nest trees). In some instances, Red-breasted Nuthatches may nest in existing cavities (instead of excavating their own) or (even more rarely) in nest boxes (Ghalambor and Martin 1999).
b. Height of Nest
Bent reported that nest cavities ranged from 2 feet to 120 feet (0.6 – 36.5 m) above ground. The average nest-hole height above ground is estimated to be 15 feet (4.6 m) and was reported to range from 5 feet to 40 feet (1.5 – 12.2 m) in Yosemite Valley (Bent 1964). In Arizona and British Columbia, nest heights have been documented as ranging from 0.7 to 31.9 m (Arizona) and 3.5 to 15.6 m (British Columbia), while another British Columbia study documented a mean cavity height of 13.1 – 15.7 m (Ghalambor and Martin 1999).
c. Height or Size of Nest Plant
Several studies cited by (Ghalambor and Martin 1999) reveal the following nest tree characteristics in Arizona and British Columbia:
Nest tree dbh: 12.5 – 112 cm with a mean of 38.6 cm; 17.3 – 36.2 cm with a mean of 26.4 cm; and 36.4 – 54.7 cm.
Nest tree height: 4.5 – 25.1 m with a mean of 12.1 m; and 14.5 to 28.2 m.
d. Plant Species Concealing Nest
See “Nest Substrate”, above. Red-breasted Nuthatches nest in tree cavities.
e. Percent Nest Cover
Because the nests are placed in a tree cavity, they are largely concealed from potential predators. The use of pine resin around the exterior of the nest entrance is thought by some to be a deterrent against predators (Ghalambor and Martin 1999).
Ghalambor and Martin (1999) describe the breeding habitat as follows: “Typically mature and diverse stands of coniferous forest, especially where spruce, fir, pine, hemlock, larch, and cedar are present, and less frequently in pure stands of pine and hemlock. May also breed in mixed woodland when strong coniferous component is associated with deciduous trees such as aspen, oak, and poplar.” In the Sierra Nevada, Red-breasted Nuthatches show a strong affinity for coniferous forests, where they favor high canopies and large trees (Ibid. 1999). Several studies reported that Red-breasted Nuthatch breeding densities were lower in managed forests where snag densities were reduced relative to densities of birds in unmanaged forests (Steeger and Hitchcock 1998). Little information exists that documents Red-breasted Nuthatch canopy cover, distance to water, slope, aspect, and ground cover habitat needs.
3. Landscape Factors
a. Elevation4. SPECIAL FACTORS
Breeding habitat occurs from sea level upward to the high-elevation montane forests (Ghalambor and Martin 1999).
Red-breasted Nuthatches avoid burned areas and recent clear-cuts. They are typically found in diverse, mature stands of coniferous forest. Logging practices that lower the diversity of the forest stand may negatively impact this species. In the Cascade Mountains of Oregon and Washington, Red-breasted Nuthatches were less common in younger forested stands and were most abundant in old-growth and mature forests of Douglas fir where standing dead trees were present (Ghalambor and Martin 1999).
c. Patch Size
No information available.
d. Disturbance (Natural or Managed)
Two elements that appear to be critical to Red-breasted Nuthatch habitat include availability of suitable nest sites (which are typically dead trees that are soft enough to allow nuthatches to excavate a cavity) and availability of a winter food source (i.e., cone-producing conifers) (Ghalambor and Martin 1999). Any disturbances that alter the availability of these habitat components will ultimately have an effect on this species. Wildfire and logging practices both have the potential to remove these habitat elements from the landscape, thereby negatively impacting the species.
The Red-breasted Nuthatch is an irruptive species, with obvious southward movements occurring in alternate years. Typically, the populations that breed the farthest north are the ones most likely to migrate on an annual basis, while the birds that breed further south may be resident year-round in non-irruptive years (Ghalambor and Martin 1999). Southward irruptions in Red-breasted Nuthatches have been linked to an inadequate supply of winter food due to poor cone crop production. It is not known to what extent climate affects the cone crop production on an annual basis.
a. Brood Parasitism5. Sensitivity to Human-Induced Disturbance
Brood parasitism in Red-breasted Nuthatches is considered to be “extremely rare”, with only two cases documented in North America (Ghalambor and Martin 1999).
See “Foraging Strategy”, above.
Like many species, the Red-breasted Nuthatch suffers appreciable mortality due to collisions with towers and buildings during migration and at or near feeders in the winter (Ghalambor and Martin 1999). As discussed above under “Disturbance (Natural or Managed)”, logging practices that remove cone-producing trees or reduce the availability of soft snags can negatively impact this species. (Ghalambor and Martin 1999) also report that logging activity that reduces the diversity of the forest stand may also negatively influence this species. In contrast, this species responds readily to availability of food at bird feeders throughout the winter.
No information available.
Predators can affect adult birds or eggs & nestlings. Predators of adult Red-breasted Nuthatches include: Sharp-shinned Hawk (Accipiter Striatus), Cooper’s Hawk (A. cooperii), Merlin (Falco columbarius), Northern Pygmy-Owl (Glaucidium gnoma), red squirrel (Tamiasciurus hudsonicus), and weasels (Mustela spp.). Steller’s Jay (Cyanocitta stelleri), House Wren (Troglodytes aedon), red squirrel, gray-necked chipmunk (Eutamias cinereicollis), weasels, Peromyscus mice, and some woodpeckers are included in the list of egg and nestling predators (Ghalambor and Martin 1999).
8. Exotic Species Invasion/Encroachment
No information Found
9. Population Trend
When considering the range-wide distribution of Red-breasted Nuthatches, populations have increased significantly between 1966 and 1996, at a rate of 2.8% per year. However, localized, non-significant population declines have been documented in Oregon and California (Ghalambor and Martin 1999).
The following summary is from (Ghalambor and Martin 1999). Both
sexes can breed in their first year and likely breed annually thereafter.
In Arizona, a nest success rate of 68.9% (percentage of nests that successfully
fledge at least one young) has been documented. However, only one
brood per year is raised. The maximum life span of Red-breasted Nuthatches
is estimated at seven years, based on results from a banded bird.
Known mortality causes include predation, exposure, disease, and starvation.
Overall continental population size is hard to estimate due to the irruptive
nature of this species. Considered to be exceptionally common along
Breeding Bird Survey routes in the central and northern Sierra Nevada and
in northwestern California coastal forests.
Studies on Red-breasted Nuthatches indicate that breeding densities are strongly correlated with dead tree density. Steeger and Hitchcock report that Red-breasted Nuthatch nest densities at their study site in British Columbia were 1 pair/1-3 ha versus 1 pair/>3 ha reported from a study in northwestern Washington, where the snag densities in the Washington study area were fewer than the British Columbia study plots (Steeger and Hitchcock 1998). Steeger and Hitchcock showed that nesting Red-breasted Nuthatches density was positively correlated with both the density of dead trees and density of trees infected by the Armillaria root-rot disease. The California Department of Fish and Game (1990) reported that in Arizona breeding densities in spruce-fir forest were 6.7 pairs per 40 ha, 20-45 pair per 40 ha in Douglas fir forest in Idaho, and ranged from 3.7 pair to 5.1 pair per 40 ha in conifer forests in the Sierra Nevada.
11. Management Issues and Habitat/Population Objectives
Managed forests that are devoid or lacking of large trees and large snags can reduce habitat quality for the Red-breasted Nuthatch. Also, harvest prescriptions that reduce and eliminate forest diseases such as root rot can decrease the available density of trees needed for nesting. The Red-breasted Nuthatch nests in areas where snags are in greater density relative to areas with fewer snags. Old forests that provide snags that are larger in diameter and taller tend to be preferred for nesting, due to the need for this weak excavator to utilize trees for nesting that have an advanced stage of tree decay. The suitability of trees used for nesting depends upon its decay characteristics. The tree species used depends upon their relative availability. A study in British Columbia reported that the Red-breasted Nuthatches did not prefer to nest in Douglas fir, perhaps due to its decay pattern, where dead Douglas fir decayed form the “outside in”. While a study in western Oregon reported that Douglas fir were used for nesting in proportion to their availability since few dead trees of other species were present (Harestad and Keisker 1989).
Management options that maintain large blocks of contiguous blocks of unmanaged forests that provide not only dead trees, but a complex forest structure that maintains the persistence of a variety of heartwood and root rot diseases to be prevalent will best provide for the Red-breasted Nuthatch. These situations are not limited to old forest conditions, but providing large trees across the landscape that grow to an old age are more likely to have decay patterns needed for the weak excavating Red-breasted Nuthatch to nest and persist (viable populations). One study cited by Ghalambor and Martin (1999) recommended that forest managers leave 36 “soft” snags and 36 “hard” snags per 40 ha. to ensure maximum population densities during the nesting period; these snags should encompass a mean dbh of 30-38 cm.
12. Associated Bird Species
In the winter, Red-breasted Nuthatches commonly join mixed-species feeding
flocks and they are also found with a variety of species – including thrushes,
vireos, chickadees, and sparrows – during migration (Ghalambor and Martin
Adams, E. M. and M. L. Morrison. 1993. Effects of forest stand structure and composition on red-breasted nuthatches and brown creepers. J. Wildlife Management 57(3):616-629.
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Burleigh, T. D. 1960. Three new subspecies of birds from western North America. Auk 77: 210-215.
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Haney, J. C. 1999. Hierarchical comparisons of breeding birds in old-growth conifer-hardwood forest on the Appalachian Plateau. Wilson Bull., 111(1), 1999. p. 89-99.
Harestad, A. S. and D. G. Keisker. 1989. Nest tree use by primary cavity-nesiting birds in south central British Columbia. Canadian Journal of Zoology 67:1067-1073.
Hendricks, P. 1995. Ground-caching and covering of food by a red-breasted nuthatch. J. Field Ornithology 66(3):370-372.
Matthysen, E. 1998. The Nuthatches. Academic Press. San Diego, CA. XX pp.
Raphael, M. G. and M. white. 1984. Use of snags by cavity-nesting birds in the Sierra Nevada. Wildlife Monographs 86.
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Small, A. 1994. California birds: their status and distribution. Ibis Publishing Company, Vista, CA. 342 pp.
Steeger, C. and C. Hitchcock. 1998. Influence of forest struture and diseases on nest-site selection by red-breasted nuthatches. J. Wildl. Manage. 62(4):1998.
Weikel, J. M. and J. P. Hayes. 1999. The foraging ecology of cavity-nesting birds in young forests of the northern coast range of Oregon. The Condor 101:58-66.
Zeiner, D. C., W. F. Laudenslayer, K. E. Mayer and M. White (editors). 1990. California’s Wildlife: Volume II Birds (California Statewide Wildlife Habitat Relationships System). State of California, The Resources Agency, Dept. of Fish and Game, Sacramento, CA. 732 pp.
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