White-headed Woodpecker Dryobates albolarvatus
Version: 2.0 — Published July 9, 2020
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Walking, Hopping, Climbing, etc.
Movement along vertical trunks typical of Dryobates woodpeckers, with short hitches using stiffened rectrices as brace. Rate of progression along trunk surface variable. Downward (tail-first) hitching along trunk is common during foraging bouts and intraspecific interactions. Hops on ground.
Typical undulating woodpecker flight, alternating quick flapping bursts with short glides. Most flights are more or less direct. Some intraspecific displays (Flutter Aerial Display; see Agonistic Behavior) involve slow, mothlike flights with exaggerated deep wing beats.
Preening, Head-scratching, Stretching, Bathing, Anting, etc.
Often pauses to preen while foraging, either on tree trunk or branch. Head-scratching and stretching frequent; scratches head directly with feet. Bathes in springs, creeks, and irrigation ditches, sometimes with mate (RDD), and also man-made water sources (e.g., bird baths, water troughs; JMK). Birds foraging at sugar pine cones with heavy external sap appear to maintain minimal contact with cones in order to minimize soiling of plumage with sap (KLG). While foraging at sap wells, spacing of lines of wells appears to allow birds to feed on sap with minimum contact of tail and feet with accumulated sap (JMK). In Washington, some adults observed with bill encrusted with sap and other exudates while foraging in ponderosa pine foliage in late July and early August; this appeared as a 1–2 cm diameter lump at the base of the bill (TJL); plumage of adults captured for banding in June and July smells distinctly of formic acid secreted by the ants they feed on (JMK).
Sleeping, Roosting, Sunbathing
The most detailed information on roosting is from Oregon (87, 72) and is summarized below. In central Oregon, 18 adult woodpeckers used a total of 110 roost trees (mean 6.11 trees/bird, range 1–13) over a period of 1–5 mo. In summer and early fall, roosts were in cavities (78%), under sloughing bark (15%), in cracks and crevices of trunks (3%), in fork of split bole (3%), or on upper trunk (1%). During breeding season, males roosted in nest cavity with young until young fledged. After first snowfall in early November, all birds roosted in cavities and used same cavity for much of winter. Most roosts (n = 64) were in ponderosa pine snags, many (n = 36) were in live ponderosa pines, some (n = 9) were in quaking aspen snags, and 1 was in a live quaking aspen. Most roost snags were in advanced state of decay; roost tree diameter at breast height (dbh) averaged 61 cm, and roost tree height averaged 20 m. In south-central Oregon, 14 adults used 52 different roost trees over a period of 1–4 mo (mean 4.0 trees/bird, range 1–7). Roosts were in cavities (85%), in crevices (4%), on trunk (2%), in fork of split bole (2%); remaining 8% could not be discerned. On one occasion, members of pair used same roost tree. Roost sites were in snags (83%), live trees (10%), stumps, and leaning logs. Mean dbh and height of roost trees (nearly all ponderosa pines) were 60 cm and 7 m, respectively.
Often calls when flying in to roost; may give displacement Tapping on roost tree or adjacent tree when intruder present. Often lands high on roost tree and hitches or hops to roost cavity entrance. Will fly out of roost if disturbed, but generally returns quickly. When roosting inside cavity, sleeps with tail sticking up against inside of cavity and head tucked to side; less commonly roosts on side of tree trunk, where it perches and tucks head underwing. Roosts in preexisting cavities. In central Oregon, individuals changed roost sites weekly to biweekly throughout summer and early fall; after first snowfall in early November, individuals used same roosts nightly through December (RDD).
Observed sunning on upper trunk of ponderosa pine snag (K. Drobish, personal communication).
Daily Time Budget
Among 83 dependent juveniles radio-tracked from 05:00–12:00 (n = 3,097 minutes) in Washington, the most common behaviors were as follows: begging for food 51%; perching quietly or preening 17%; foraging or pecking 16%; and calling (other than begging calls) 5% (TJL). In the afternoon (12:00–16:00), the most common behaviors were (n = 2,643 min): begging for food 44%; perching quietly or preening 25%; foraging or pecking 14%; and calling (other than begging calls) 5%. Among 39 adults radio-tracked in Washington (predominately May–October), the most common morning behaviors while birds were away from their nest were (n = 5,924 min): foraging 83%; perching quietly or preening 5%; flying 4%; calling 4%; and chasing intruders 1% (TJL). Common afternoon behaviors (n = 8,163 min) were: foraging 83%; perching quietly or preening 7%; flying 4%; and calling 3%.
Intraspecific aggression found to be absent in a study of gravirostris (93). Physical contact during interactions is rare, but there is a case of 2 males near nest locking together and falling through air nearly to ground before separating (RDD). In Washington, adult males have been successfully captured by placing noose traps adjacent to taxidermy mounts of male and female White-headed Woodpeckers during the early breeding season (April–May), with playbacks of White-headed Woodpecker drumming and calls (67). Five males were successfully captured with these methods, but no females. One male attacked the taxidermy mount, pulling out feathers and cracking the skull before he was successfully captured.
Several ritualized postures and behaviors described by Short (32) for New World Picoides [Dryobates] woodpeckers are noted during interactions between White-headed Woodpeckers. Names of behaviors (capitalized) are from Short (32). These include: Crest Raising, in which the crown feathers (including the red nuchal patch of males) are erected (Crest Raising is also performed by captured birds during handling by investigator; KLG); Head Swinging, a back and forth lateral movement of the bill and head; Wing Flicking, a rapid outward then inward flick of one or both wings; and rarely Wing Spreading, in which both wings are held fully extended for a brief period. Adults, presumably from neighboring territories, may engage in stereotypical chase/freeze sequences (KLG). Most such sequences have been observed between 2 males, but chase/freeze sequences between 2 females also occur. In Washington, all intraspecific interactions observed involved birds of the same sex; e.g., when territorial aggression observed between 2 males or 2 females, the other sex of the mated pair often in close proximity, but does not participate in aggressive interactions (JMK). These sequences involve rapid exaggerated hitching movements (up, down, or lateral), with the 2 birds within 1–2 m of each other, alternating with prolonged "freezes" during which each bird is completely still, with neck outstretched. Head-up postures, side-to-side Head-swinging, slight Wing-spreading, quick wing flicks may all occur between freeze postures. Most freeze postures maintained for 10–30 s; longest timed freeze of gravirostris in San Gabriel Mountains, California, was 162 s (KLG). Movement phase begins again suddenly. These ritualized chase/freeze sequences accompanied by chewk chewk... or kweek kweek kweek... series; may last up to 30 min. The Flutter Aerial Display (32) is given during aggressive encounters between individuals (usually of same sex), most frequently early in the breeding season, as well as in nest demonstration display (see Sexual Behavior). This display involves slow, "moth-like" flight with exaggerated, halting wingbeats.
The size of area that is actively defended against other breeding pairs is unknown and varies based on the suitability of habitat, date within the breeding season, and individual disposition. Lorenz et al. (67) estimated that 50% core areas averaged 23.4 ha during the breeding season, compared to 124.9 ha for the 95% home range. Some defense of home range has been seen outside the breeding season (RDD), but territoriality appears relaxed after the breeding season as evidenced by unsuccessfully nesting adults and juveniles foraging in close proximity during August–September (JMK). In suitable habitat, 95% home-range kernels frequently overlap, even during the breeding season (67). See Demography and Populations: Population Spatial Metrics for further details on territory size, home range size, and individual distance.
Drumming (see Sounds and Vocal Behavior: Nonvocal Sounds) likely functions in territorial advertisement, as both males and females will drum in response to call playback of conspecific drumming (JMK). Displacement drumming also frequently given in response to investigator near an active nest; perhaps functioning as a display of agitation (JMK). Chase/freeze sequences (KLG), Flutter Aerial Display (see Nonvocal Sounds) (5), and Wing Ruffle (see Nonvocal Sounds) given during territorial conflicts (JMK); actual physical contact appears rare.
Little data on dominance hierarchies. Ligon (88) believed that males were socially dominant over females, though formal studies have not been conducted with this species. Juveniles will displace parents from feeding perches while begging for food (TJL), crowding the parents of feeding perches while begging loudly, though this does not necessarily mean than juveniles are dominant.
Will defend feeding sites (e.g., cones, sap wells) from heterospecifics, including Hairy Woodpecker (Dryobates villosus) (see Behavior: Social and Interspecific Behavior). Tendency to avoid vicinity of colonies of Acorn Woodpecker (Melanerpes formicivorus) noted by Hilkevitch (93). On the other hand, in Washington and Oregon this species commonly nests in close proximity (< 100) and certainly within hearing and sight range of other cavity nesting birds, such as Hairy Woodpecker, Black-backed Woodpecker (Picoides arcticus), Northern Flicker (Colaptes auratus), Williamson's Sapsucker (Sphyrapicus thyroideus), Red-naped Sapsucker (S. nuchalis), House Wren (Troglodytes aedon), and Western Bluebird (Sialia mexicana) (TJL, JMK).
Mating System and Operational Sex Ratio
This species is socially monogamous. Genetic studies of parentage have not been conducted but observational studies and studies with other woodpecker species suggest that this species is genetically monogamous as well.
In Washington, among 157 nestlings banded and sexed by plumage, 43% were female and 52% were male (5% could not be sexed) (TJL). Also in Washington, 55 nests inspected to monitor nest survival contained a total of 150 nestlings in which 37% were female and 63% were male (JMK). However, as noted in Appearance: Molts, the red crown patch on nestlings is variable and thus sexing nestlings by plumage is not 100% accurate; some males could have little evidence of red feathering while in the nest and some females may have more extensive red feathering. Of 81 juveniles and adults captured and banded away from nest cavities over a 7-year period in Washington, 52% were females and 48% were males (JMK).
Courtship, Copulation, and Pair Bond
Nest demonstration display in which one bird, usually male, gives Flutter Aerial Display toward nest hole, giving kweek call in flight and Twitter Call upon landing (5).
Copulation observed when nest is completed, May–early June (as early as 14 April in southern California; KLG), but also observed prior to cavity completion in Washington (as early as 20 March; JMK). Typically female flies in and gives Rattle Call to male, who is at, near, or inside nest cavity. Female flies to horizontal branch near nest tree; male flies out. Soft chewk chewk chewk notes and wing-quivering in both sexes precede copulation. After copulation, male flies away, and female flies to and enters nest cavity, giving Rattle Call. Alternatively, both members of pair may fly off after copulation. Postcopulation flight often slow, with exaggerated moth-like wing beats (KLG). Three timed copulations lasted 3 s, 8 s, and 10 s (KLG; K. Drobish, personal communication).
Color-banded pairs have been observed together on territories in all seasons of the year (111, RDD, JMK). In Washington, a color-banded pair was found on the same territory for 5 consecutive years and 2 additional color-banded pairs remained on the same territory for 4 consecutive years (JMK).
Apparent pair reinforcement behavior was noted in late January in the Sierra Nevada, California (111), suggesting year-round pair bond. Pairs also observed together in winter in Oregon (RDD) and Washington (JMK). Color-banded pair observed together 27 December in Oregon within 50 m of that year's nest (RDD). In Washington, color-banded pairs observed in subsequent years on same territory from January–October (JMK). However, there is no information on the average duration of pair bonds or what proportion of adults remain paired throughout the winter.
Extra-Pair Mating Behavior/Paternity
Brood Parasitism of Conspecifics
Unknown, but records of clutches of 7–9 eggs (WFVZ) suggest laying by > 1 female.
Brood Parasitism of Other Species
Social and Interspecific Behavior
Degree of Sociality
Not normally social, apart from pair bonds and family groups.
Not formally studied. Radio-tagged dependent juveniles (< 35 d post fledgling) have been observed picking up sticks in their bill (n = 1) and entering/exiting cavities in snags (n = 3) during the daylight hours, for seemingly no purpose and suggestive of play (TJL). On 9 occasions, juveniles (mean 17.6 d post-fledging) were observed approaching humans extremely closely; these juveniles flew directly towards humans and perched within 5 m in a nearby tree for an average of 8.3 min (TJL).
Nonpredatory Interspecific Interactions
Female drove Pygmy Nuthatch (Sitta pygmaea) and Red Crossbill (Loxia curvirostra) from cones in Idaho (88). Male and female Hairy Woodpecker noted supplanting female White-headed Woodpecker from cones, but male White-headed Woodpecker supplanted female Hairy (88); in Oregon, a male Hairy Woodpecker displaced a male White-headed Woodpecker (RDD); in Washington, Hairy Woodpecker was frequently observed supplanting White-headed Woodpecker at foraging sites (JMK). Williamson's Sapsucker has been seen taking over White-headed Woodpecker sapwells and subplanting adult White-headed Woodpecker (TJL). A male White-headed Woodpecker observed to repeatedly chase a Red-naped Sapsucker from sap wells the White-headed Woodpecker had drilled (JMK). Does not appear to associate with mixed-species foraging flocks (e.g., chickadees, nuthatches, kinglets, etc.) in winter as Downy Woodpecker (Dryobates pubescens) and Hairy Woodpecker are known to do; White-headed Woodpecker is more often observed foraging alone or in loose association with mate in winter (JMK). Hilkevitch (93) noted conspicuous absence of interspecific aggression in gravirostris population in San Gabriel Mountains, California. Foraging by Hairy Woodpecker on cones of ponderosa pine was frequent in Colorado from mid-October to February (112); there is thus potential for competition for pine seeds where villosus is sympatric with albolarvatus in Pacific states. A Gray Flycatcher (Empidonax wrightii) was observed striking a male White-headed Woodpecker in mid-flight and driving it to the ground; presumably because the woodpecker had gotten too close to the flycatcher's nest (JMK). Spreads wings in a threat display and pecks at small mammals (e.g., yellow pine chipmunk [Neotamias amoenus]) to drive them from water sources (JMK).
Interspecific interactions around nest site frequent, especially between White-headed Woodpecker and other cavity-nesting species. In particular, Mountain Bluebird (Sialia currucoides), Western Bluebird, Pygmy Nuthatch, and Violet-green Swallow (Tachycineta thalassina) show aggression toward White-headed Woopecker, and vice versa, sometimes resulting in abandonment of excavation efforts by the woodpeckers (RDD, KLG, JMK). Although House Wren was observed to enter White-headed Woodpecker cavities during excavation in Washington, there was no evidence that House Wren usurps this woodpecker's cavities or pierce their eggs (JMK). In Oregon, a White-headed Woodpecker nest, prior to egg-laying, was usurped by northern flying squirrel (Glaucomys sabrinus), and another by pair of European Starling (Sturnus vulgaris) during incubation (RDD). In Washington, one nest was usurped by Mountain Bluebirds and another by European Starlings prior to egg-laying (JMK). White-headed Woodpeckers have been observed chasing chipmunks (Neotamias spp.) from woodpecker's nest snag (RDD, TJL); a male was noted chasing a Merriam's chipmunk (N. merriami) in San Bernardino Mountains, California. In Washington, a male White-headed Woodpecker observed chasing and repeatedly striking a Douglas squirrel (Tamiasciuris douglasii) that was near its nest containing young (JMK) and another male woodpecker observed attacking an American Kestrel (Falco sparverius) that had its leg in the woodpecker's nest cavity attempting to capture a nestling (113). Also, in Washington, adult male was observed chasing long-tailed weasel (Mustela frenata) that was depredating a nest containing nestlings; the woodpecker was not successful in preventing depredation in this case (TJL).
Remains of one White-headed Woodpecker were found beneath the nest of a Cooper's Hawk (Accipiter cooperii) in Oregon. In another case, an immature Cooper's Hawk was observed chasing and striking a female woodpecker, but she escaped (RDD). Predation on adults by Great Horned Owl (Bubo virginianus) recorded in Oregon (RDD). Among 128 adults and juveniles radio-tracked in Washington, deaths were attributed to the following causes: 2 Cooper’s Hawk; 6 Northern Goshawk (Accipiter gentilis); 1 death from an unidentified accipiter; 1 death from the blood parasite Haemoproteus velans (114; TJL) These causes of death were determined by tracking transmitters to raptor nests, finding transmitters at sites with adult or juvenile raptors present, or from necropsy. Three additional transmitters were found in middens of Douglas squirrel (Tamiasciurus douglasii). Evidence points to 6 additional deaths from unidentified raptors, and 3 additional deaths from Northern Goshawk. In Washington, remains of adult woodpecker found in a nest cavity that was presumably killed by a long-tailed weasel, and black bear (Ursus americanus) and Common Raven (Corvus corax) documented predating nest cavities (115, JMK). In another study using continuous video monitoring of 56 nests in Washington, successful predators of nestlings included American Kestrel (n = 1) and long-tailed weasel (n = 1; TJL).