Species: White-breasted Nuthatch (Sitta carolinensis) or WBNU. There are several subspecies (up to 8?) with varying plumage. Hybridization with other species of nuthatches - the Red-breasted (S. canadensis), Pygmy (S. pygmaea) or Brown-headed (S. pusilla) - has not been documented.
Not much is known about nuthatch biology because they usually nest in trees as opposed to nestboxes.
Their bill is almost as long as their head, and it is the longest of the American nuthatches.
They wedge large seeds or nuts into the crevices and then pound or tear them open with their beak.
They also scatterhoard food, with one food item in each cache. May even hoard mealworms and suet.
They have been seen plucking chunks of fur from dead animals (squirrel, rabbit) for nests.
To "defend" a nest, they may use bill-wiping or sweeping (with an object like a crushed insect) for minutes at a time, inside and outside the nest. May also stand still while spreading its wings and swaying to distract.
R.W. Williams (1918) reported shooting and killing a Red-headed Woodpecker that attacked a nuthatch nest and threw the young on the ground (Bent).
Photo above by Wendell Long.
Photo below by Judy Derry.
Identification: Chunky little bird with a short neck, white face and breast (with rusty sides) and a short tail. Males have a black crown, the crown is often gray on females. Broad-shouldered, with bluish-gray wings. The bill is long and slightly upturned, and is dark bluish-slate above, and lighter at the base. Often walks, hops or clings with the head facing downward. Make 13 different calls, including a sort of nasal "quank" and "hah-hah-hah."
The Red-breasted Nuthatch, which is more common in boreal coniferous forests, has a black eyeline and reddish underparts.
Distribution: Usually resides in pairs year-round in the same territory, perhaps about 25-50 acres (Bent). Found in much of the US, into parts of southern Canada and South America. Not found in treeless areas. Populations appear to be on the increase. BBS Map
Diet: Pokes around in bark for insects (tree hoppers, wood borers, ants, gypsy moth larvae, forest tent caterpillars, weevils, etc.) and seeds (acorns, beech and hickory nuts, corn, sunflower seeds, etc.). Common visitor at bird feeders. Enjoys suet and mealworms. May eat from a person's hand.
Preferred Nesting Habitat: Mature deciduous woodland, but also mixed deciduous and coniferous forest, preferring forest edge near open areas (water, road, clearing, field) near nest. In California may or may not prefer oak. Prefers natural holes in large (e.g., 17" diameter), old or decaying trees.
Nestboxes: Prefers woodpecker holes (e.g., flicker) or natural cavities. Probably competes with squirrels for nest sites. Not common in nestboxes (no published information on use?) May roost in boxes. May refuse to nest in a box mounted on a pole, instead preferring tall trees with the box mounted 12-20 feet high. Reports of nesting in a baffled box on a post under a tree canopy. Large loose chunks of bark attached to the nestbox may be attractive, along with an entrance hole in the upper back corner on the side of the box (with no overhang) and with the hole nearly hidden by a larger branch coming out right beside the entrance hole. Musser had them nest in a chalet style box, with a perching ledge to the side of the hole, and a roof with minimal overhang in the front that enabled the bird to walk head down towards the hole. 1-4" of wood shavings (not sawdust) placed in box may promote "excavation."
Height: Holes in trees are 10 or 16 to 65 feet above the ground; or 15-50 feet (Bent). Some say at least 8', others say at least 10-12 feet high (Corkran). Chuck Musser had them nest in a 5 foot high box on his deck railing.
Dimensions: Cavities in trees may be 6-8" deep, usually 6" from entrance (Bent). Other sources recommend 8-11 depth, and a 4" x 4" floor. Musser feels a 4x4" floor is too small, and had them nest in a box that had an 7.5 x 7.5" floor. The box was 3.75" inches from the bottom of the hole to the floor.
Hole size: Various sources say 1 1/8", 1.25", to 1.5." Consider the broad shoulders. Since I think cavity nesting birds tend to be attracted to a larger hole, I would do 1.5" and if needed add a hole restrictor after the first egg is laid, on the inside of the box. Musser's box had a 1.5" entrance hole.
Direction: In one study, most holes faced south (McEllin 1979).
Nestbox Location: At or near winter feeding territory. May nest in the same hole for successive seasons (Bent). Try within 15-30 feet of trees. (Musser's nestbox was about 61 feet from the treeline. The closest feeder was about 45 feet away.) Avoid a lot of dense branches to allow swooping dive entry from neighboring trees.
Recommended distance between nestboxes: As close as 150 feet apart if there is some screening vegetation in between? (Corkran)
Monitoring: At least for Brown-headed nuthatches, the nest is fragile and can blow away during monitoring. WBNU nests are more tightly packed. They are not known to abandon nests due to weekly monitoring. If one is inside the box when it is opened, they may remain, moving up underneath the roof.
Nesting Timetable (typical):
Excavation or nest site selection: Parents probably start breeding in their first year. Primarily a secondary cavity nester (rarely excavate their own?) Nest in existing cavities and knotholes, occasionally use nestboxes. May start checking out nest sites in March, and nest in early April through May.
Nest construction: The female builds the nest. Base may be about 1/2" of bark (flakes and strips) and pellets of dried earth or lumps of mud. Matted nest of bark shreds, small twigs, grasses, rootlets, with a little fur, hair, feathers, cellophane, cigarette butts. Cup may be indistinct and saucer shaped.
Egg laying: 5-9, possibly 10 (typically 7-8) eggs laid March through June (typically mid-April before leaves are on trees, through May). Shell smooth, very little gloss, white (can be creamy or pinkish-white), usually heavily marked with light cinnamon brown/red/ lavender/gray speckles and spots, often denser at larger end (looks almost bloody). Subelliptical to short subelliptical. Eggs may be covered with nesting material when the female leaves the nest.
Incubation: 12-14 days, starting with the laying of the last egg? Only the female incubates. Male comes in to feed female.
Hatching: May hatch 1 day apart. 12 days? Altricial. Newborn babies have globe shaped heads with bulbous black eyes, a very pointy but short beak, and tufts of a few gray downy feathers on their head. Legs and toes are long compared to body. Unhatched eggs may be removed by the parent(s).
Development: Both parents feed animal matter, no seeds? The female broods the hatchlings for the first few days. Parents remove fecal sacs. A begging call within 24 hours of hatching.
On Musser video (counting day they hatched as Day 1):
By Day 5 after hatching, the beak was noticeably pointier.
Day 6, cap starts to become visible.
At Day 7, pink skin less visible - mostly blue.
By Day 8-9, pin feathers are visible.
By Day 12 cap is more noticeable, eyes slits.
Eyes open on Day 13.
Day 14-15, cap is very noticeable with side tufts.
On Day 15, nestlings hunkered down when monitored.
On Day 17, white alongside cap was more noticeable. Parents were still removing fecal sacs
Fledged on Day 23-24.
Fledging: Day 19 - 26? 14-17? after hatching. May fledge over 2 day period. Young are able climbers but do not fly well. May cling to box in the process of fledging. Bills and feet of recently fledged birds are dusky pinkish-buff. Juvenile breast feathers are whiter on the breast. Young stay with parents for several weeks.
Dispersal: All young apparently leave the territory where they were raised. It's possible that juveniles "irrupt" into areas with fewer nuthatches or more food.
Number of broods: They do not re-nest after a failure, and no second clutches have been reported.
Longevity: Little banding data. Maybe less than 2 years. Longest reported life span is 9 years 10 mos. (Klimkiewicz et al 1983).
Other names: Sita pecho blanco [Spanish]; sittelle à poitrine blanche [French]
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