Behavior

Locomotion

Walking, Hopping, Climbing

Climb up, down, and around tree trunks and branches, and often cling upside down. While headed downward on the side of a tree, they commonly lean outward and hold the head horizontally while viewing their surroundings. On the ground, the birds hop.

Modifications made for habitual trunk foraging discussed in detail by Richardson (1942); e.g., feet placed far apart at slight angle to direction of trunk and tail not used for support. As a result, hallux large compared to other trunk foraging birds that do use tail for support (e.g., woodpeckers), and rectrices and skeletal parts of the tail reduced. Bill adapted for both probing and pounding.

Flight

No detailed information.

Swimming And Diving

Not recorded.

Self-Maintenance

No information on preening or daily time budgets; anting not known (Potter and Hauser 1974). Known to sunbathe (Potter and Hauser 1974)

Agonistic Behavior

Physical Interactions

Always chase conspecific intruders from their territory, usually via threat postures but sometimes using physical contact. In one case, two males flew at each other, “fluttering beak to beak in mid-air” (Kilham 1981).

Communicative Interactions

Six aggressive displays recognized (Kilham 1971):

Tail-fanning. Bird raises and fans its tail, displaying the pied black and white coloration of the rectrices. Given by a female, usually, when male approaches the nest where female is dominant, or in conflicts with other pairs.

Wing-flicking. Combined with Tail-fanning, and used primarily as an antipredator display.

Threat Display. The bill is raised, wings lowered and tail raised. This posture is assumed by a subordinate bird when threatened by a dominant.

Aggressive Threat Display. In addition to the foregoing, a bird raises the back feathers and points the head and bill downward. Usually given in severe conflicts; e.g., exchanging use of a particular roost hole with Downy Woodpeckers (Dendrocopos pubescens; Kilham 1971). Regularly remove feces from roost-holes. In early spring, dominance at the roost hole reverses, the female taking over a hole formerly occupied by the male.

Raised Back Feathers. While wing and tail in normal position. Common when one nuthatch is about to attack another, or when a male is about to start flying to his mate before a pursuit flight.

Bill Pointed Forward. A display used by a female toward a male intruder near the nest or toward a juvenile she is driving away.

Spacing

Territoriality

Live in pairs, generally in same territory year round (Butts 1931, Bent 1948, McEllin 1979b). Some individuals appear to move from one territory to another (Butts 1931). If a member of a mated pair disappears, such a floater may take its place.

Territory typically 10–15 ha in wooded places and about 20 ha in semi-wooded sites (Butts 1931). See also Demography and Populations: population status, for estimates/counts of density in different regions and forests. In Eurasian Nuthatch, territory ranges from 2–10 ha in Europe to 41 ha in e. Siberia (Enoksson 1988, Pravosudov, 1993).

Except, perhaps, for a brief period early during the breeding season, the male of a pair of White-breasted Nuthatches always dominates the female (Waite 1987). As predicted by theory (e.g., Clark and Ekman 1995), males, with the relatively more predictable food supply as a consequence of their dominant position, carry significantly less fat in winter than do females (Pravosudov et al. 1999).

Individual Distance

No information.

Sexual Behavior

Mating System And Sex Ratio

Socially monogamous, pairs remain together from the time they establish a territory until one of the partners disappears. No separations reported (Butts 1931, Bent 1948).

Pair Bond

Pair bonds maintained year round (Butts 1931, Kilham 1972).

Courtship has several components (Kilham 1972):

Breeding song. Given by males most actively in the first half hour of winter mornings. After a female approaches, a male may continue singing and start to display his plumage on the back of the head and body to her while she stays near.

Hit-tuck notes. Frequently exchanged between partners during the day in winter and early spring.

Phee-oo note. Presumably expresses a high level of sexual excitement and is given by a male when flying to his partner, precipitating a pursuit flight. It is also given by a female when inviting copulation.

Courtship feeding. Courtship feeding of three types begins in winter: (a) a female in a motionless pose raises her beak in a fixed position, causing a male to approach her with food; (b) a female gives the begging call typical of older nestlings, with beak open and wings quivering and (c) during the egg-laying period, a female may take repeated feedings from a male without display.

Courtship feeding is also very common in Eurasian Nuthatches (VVP). In e. Siberia, a male fed a female in the nest hole an average of 1.2 ± 1.4 times/h throughout the incubation period. However, no information is available for either the White-breasted or Eurasian Nuthatch on what proportion of a female’s diet is due to feedings by the male.

Copulation

In one episode described by Kilham (1972), a female initiated copulatory behavior by squatting low on a perch with the tail up, head upward, and gave phee-oo notes. She fluffed out her flank feathers, making her appear larger. The male hopped around the female with his tail cocked up, head stretched upward, and neck twisted at an angle of 45°. He then moved around to her right side, passed under her beak, hopped on her back, and fluttered to hold his position there. After bending his tail under hers, he fell sideways and moved away. The female remained briefly in the same position, continuing to call phee-oo and moving her beak from side to side.

Extra-Pair Copulations

No data on frequency of extra-pair copulations or extra-pair fertilizations.

Social And Interspecific Behavior

Degree Of Sociality

Normally territorial, nuthatches may leave their territories in winter to reach a rich food source such as a bird feeder (TCG).

During fall and winter, pairs may forage in flocks led by chickadees and/or titmice (Berner and Grubb 1985). In such flocks, White-breasted Nuthatches are an example of what is called a “satellite species.” As a mixed-species foraging flock moves through the habitat, satellite species follow along after species termed “nuclear species,” e.g., chickadees and titmice (Waite and Grubb 1988b). Such nuclear species tend to be highly vocal and active. At the boundary of their territory, a pair of nuthatches drops out of such a mixed-species foraging flock, and the neighboring pair joins it. Such interspecific feeding assemblages break up in late winter as chickadees and titmice begin to establish their own breeding territories (TCG).

In a manipulative study, Dolby and Grubb (1999b) tested the notion that various satellite species forage in each other’s company only because they are all following the same nuclear species. Chickadees and titmice were removed from treatment woodlots, but left in control woodlots. The woodlots used in the study were all of a size that would be occupied by only one mixed-species flock each. During 81% of survey visits to control woodlots, at least one White-breasted Nuthatch and one Downy Woodpecker (Picoides pubescens), the other major satellite species in the habitat, were foraging within the same 25 x 25 m block of woodland. However, in treatment woodlots, such associations were found on only 44% of survey visits. These results indicate that there is little intrinsic attraction among satellite species in a habitat and that whatever association they may reveal with each other is an unselected consequence of their independent attraction to nuclear species.

Dolby and Grubb (1998) used removals, again of chickadees and titmice, to pursue the effects of nuclear species on the behavior and nutritional condition and survivorship of satellite species. Results supported the idea that satellite species rely on nuclear species to detect incoming predators, so can devote more time to looking for food and less to being vigilant for predators.

To what extent is a nuthatch aware that foraging with nuclear species reduces its predation risk? In the same Ohio landscape of woodlots in a sea of corn and soybean fields, Dolby and Grubb (2000) explored this question by investigating nuthatch “risk-taking” in the presence and absence of chickadees and titmice. Mobile feeders were placed either 8 m or 16 m out into fields from the edge of woodlots, and the distance nuthatches were willing to fly away from cover was recorded in the presence and absence of the nuclear species. The flock composition of nuclear species was standardized as either two titmice or no titmice; all other titmice and chickadees were removed from all flocks. As predicted, nuthatches delayed longer before venturing 16 m to food than when having to fly only 8 m. Furthermore, more nuthatches refrained entirely from using the 16-m feeder when there were no titmice present.

Play

Not recorded.

Predation

Kinds Of Predators

No information on predation of adults; probably small hawks and owls. In one study of the Eurasian Nuthatch, 7 of 113 nests were destroyed by predators (Nilsson 1984). House Wren (Troglodytes aedon) assumed to be an egg predator (Ghalambor and Martin 2000).

Manner Of Predation

Bent (1948) reported an observation by R. W. Williams of two Red-headed Woodpeckers (Melanerpes erythrocephalus) attacking a nuthatch nest and young.

Response To Predators

White-breasted Nuthatches react to the presence of a predator by pecking, with rapid hn-hn sounds, while the tail is slightly raised and wings are occasionally flicked (Kilham 1981). Individuals closely approached realistic or crude models of snakes, sometimes hopping on the ground nearby (Bryan 1998). Are attracted to playback of the mobbing vocalizations of Black-capped Chickadees (TCG).

Life-history theory predicts that species with greater fecundity and lower annual survivorship should be more risk-prone regarding nest predators and less risk-prone to adult predators than should species with lower fecundity and higher annual survivorship. White-breasted Nuthatch response to taxidermic mounts of House Wren (nest predator) and Sharp-shinned Hawk (Accipiter striatus) supported this idea. In the same study site in Arizona, male White-breasted Nuthatches (higher fecundity, lower survivorship) fed the incubating female less in the presence of the wren mount and more in the presence of the hawk mount than did male Red-breasted Nuthatches (lower fecundity, higher survivorship; Ghalambor and Martin 2000).