Pileated
Woodpecker
Dryocopus
pileatus FRENCH: Grand Pic
HABITAT
BREEDING RANGE
Late successional stages of coniferous or deciduous forest, but also younger forests that have scattered, large, dead trees. In Virginia prefers to nest in mesic areas, close to streams; selects stands with greatest basal area, greatest density of stems, and highest crown canopy (Conner and Adkisson 1976). In Missouri there is a positive relationship between woodpecker abundance and amount of bottomland forest, of density of trees >30 cm diameter at breast height (dbh), and of dead trees >54 cm dbh; there is a negative relationship with area covered by [smaller diameter] pole timber (Renken and Wiggers 1993); home range size is inversely related to log and stump volume and canopy closure (Renken and Wiggers 1989). In n. Louisiana there were 3 6 pairs/1,580 ha of virgin timber but <1 pair/1,580 ha of second growth (Tanner 1942). In ne. Oregon, selects unlogged stands of old-growth grand fir (Abies grandis) with closed canopies (Bull and Holthausen 1993). In w. Oregon, densities are greater in forests >80 yr old than in younger ones (Nelson 1988). Also in w. Oregon, prefers forests >40 yr old and riparian habitats for foraging, forest stands >70 yr old for nesting and roosting (Mellen et al. 1992). In w. Washington, most radio-telemetry locations (64% males, 61% females) are in old-growth forests (Aubry and Raley 1993).
ROOST SITES
Roosts in hollow trees or vacated nest cavities at night and during inclement weather (Fig. 2). In ne. Oregon, of 443 locations of 22 adults at night, all roosted in cavities; each bird used an average of 7 (range = 4 11) different roost trees in a 3- to 10-mo period (Bull et al. 1992b). Roost cavities are in live and dead trees. Of 60 roost trees climbed, 95% had a hollow interior created by decay rather than excavation. Woodpeckers typically excavate only the entrance hole to gain access to the hollow interior of a tree and thus conserve energy because an entire cavity is not excavated. Roost trees typically have 1 16 entrance holes in the trunk, providing alternate escape routes should a predator enter the roost. In Iowa, also roosts in live hollow trees with multiple entrances (Downing 1940).
Roost trees in ne. Oregon typically are in old-growth stands of grand fir that have experienced little or no logging and have >60% canopy closures. Although the roost tree is typically a live or dead grand fir, ponderosa pine (Pinus ponderosa) and western larch (Larix occidentalis) are also used (Bull et al. 1992b). Of 73 roosts found in w. Washington, 52% were in western hemlock (Tsuga heterophylla), 42% in western redcedar (Thuja plicata), and 5% in Pacific silver fir (Abies amabilis) (Aubry and Raley 1994); 63% of w. Washington roosts in dead trees (Aubry and Raley 1994); 86% of roosts located in old-growth stands (Aubry and Raley 1993); mean tree dbh and height: 126 cm and 35 m (Aubry and Raley 1992). In w. Oregon, Douglas-fir (Pseudotsuga menziesii), red alder (Alnus rubra), western redcedar, and big-leaf maple (Acer macrophyllum) contain roosts (Mellen 1987). In Montana, roosts in western larch, black cottonwood (Populus trichocarpa), and ponderosa pine (McClelland 1977).
BREEDING
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PHENOLOGY
Breeds earlier in southern and coastal areas, later at northern and high-elevation sites. Representative geographic variation in breeding phenology is shown in Appendix 1. Time of nesting season is significantly related to elevation in California (Harris 1982). May be affected by weather in w. Washington because nested 3-4 wk later in a wet spring (K. Aubry and C. Raley pers. comm.).
Pair formation. Pair shares territory all year, but courtship and intensified territorial activity begin Feb Mar in w. U.S. (ELB).
Nest-building. See Appendix 1 for dates.
First/only brood per season. Only 1 brood/season. May renest if first attempt fails early (Truslow 1966, ELB). Within an area, phenology may vary with altitude, e.g., in California young fledged in mid-May at coastal sites and in late May through early Jul at montane sites (Harris 1982). See Appendix 1 for dates.
NEST SITE
Selection process. Lawrence (1970) reported that male selected nest site and started excavation.
Microhabitat. Nest trees are typically dead and within a mature or old stand of coniferous (McClelland 1977, ELB) or deciduous trees, but may be in relict dead trees in younger forests or even in cities (particularly in e. U.S.; Bull 1974).
Site characteristics. Of 105 nest trees in ne. Oregon, 75% in ponderosa pine, 25% in western larch, 2% in grand fir; all trees but 1 were dead; mean dbh and height of tree: 84 cm and 28 m; 15 m mean height of nest hole (Bull 1987). Of 22 nests in w. Washington, 68% in western hemlock, 27% in Pacific silver fir, 5% in red alder; 45% in live trees; mean dbh and height: 97 cm and 41 m; 38 m mean hole height (K. Aubry and C. Raley unpubl. data). In w. Oregon, 73% of nests in Douglas-fir snags, 20% in alder snags, 7% in live Douglas-fir; mean dbh and height: 69 cm and 27 m; 20 m mean hole height (Mellen 1987). In Kentucky, nests in elm (Ulmus sp.), sweet gum (Liquidamber styraciflua), maple (Acer sp.), yellow poplar (Liriodendron tulipifera), red oak (Quercus rubra), hackberry (Celtis occidentalis), and sycamore (Platanus occidentalis) (Mengel 1965). In Virginia, 28% of nests in hickory, 22% in red oak, 17% in chestnut oak (Q. prinus), 11% in white oak (Q. alba), 5.5% each in white pine (Pinus strobus), sugar maple (Acer saccharum), sycamore, and yellow poplar; mean dbh and height: 55 cm and 20 m; 14 m hole height (Conner et al. 1975). Fungal activity in all nest trees in Virginia had weakened the wood (Conner and Adkisson 1976).
NEST
Construction process. Parental Roles. Both sexes excavate, but male does more work (Hoyt 1957). Kilham (1979) reported that males did twice as much excavating as females in Georgia. Males did 2 5 times more excavating than females in ne. Oregon (Bull and Meslow 1988). Intruders are chased off by one or both of mates.
Method of construction. Bird excavates cavity by striking tree with bill and chipping away wood. It chips at wood for several minutes, then tosses billfuls of chips out of cavity, sometimes > 40 billfuls in succession (Kilham 1979). When cavity is started, bird excavates while perched on trunk; as cavity gets deeper, bird excavates with tail sticking out of hole; bird excavates from inside cavity when near completion (ELB).
Time of day. Birds excavate at all times of day but more frequently in morning.
Length of time to build nest. In Oregon, 3 6 wk (ELB); in Kentucky, 23 d (Bacon 1954).
Structure and composition matter. Nest cavity is constructed in sound or decayed wood; chips are left in bottom of cavity.
Dimensions. Variations in nest-cavity dimensions are given in Table 1. Christy (1939) describes the following ranges (converted from inches to nearest 0.5 cm) in nest dimensions without providing locality data: cavity depth (not defined) of 25 61 cm (with extremes of 15 and 66 cm), mean of 15 cavities = 48 cm; diameter of bowl at bottom of nest = 15 16.5 cm. In ne. Oregon, thickness of wood at entrance hole averages 6 cm, and tree diameter at entrance averages 60 cm (n = 50) (Bull 1987). Hoyt (1957) found tree diameter at a New York nest to be 44.5 cm.
Microclimate. Cavity is completely enclosed; has good insulative value. Orientation of nest entrance is not random; in ne. Oregon, 71% faced between a northeast and southwest direction, typically on underside of a leaning tree (Bull 1987). In Virginia, 22% of nest entrances faced north, 22% south, 22% west, and 33% east (Conner 1975).
Maintenance or reuse of nests, alternate nests. Old nest cavities may be used as roost sites but are rarely used for nesting again. Alternate nests may be available; several nest starts are excavated by pair each spring. Partially completed cavities are sometimes completed in later years and used as nests (Bull and Meslow 1988).
EGGS
Shape. Broadly oval with both ends flatly rounded.
Size. Dimensions (mm) from Western Foundation of Vertebrate Zoology (WFVZ): D. p. abieticola: length = 32.85 (range = 30.26 34.74), breadth = 24.83 (23.86 26.36) (n = 20 clutches, 65 eggs). D. p. pileatus: length = 33.45 (31.64 35.86), breadth = 24.25 (22.60 25.44) (n = 21 clutches, 84 eggs). D. p. picinus: length = 32.73 (31.78 33.57), breadth = 24.64 (23.74 26.00) (n = 4 clutches, 10 eggs). D. p. floridanus: length = 32.35 (30.82 33.53), breadth = 24.43 (23.37 25.38) (n = 9 clutches, 34 eggs). Average dimensions (mm) reported by Bent (1939): 33.16 x 25.21 for northern subspecies (n = 51), 32.90 x 24.72 for southern subspecies (n = 52). In California, average dimensions (mm) reported by Harris (1982): 23.5 x 34.0 (n = 8).
Mass. Weight of 8 eggs ranged from 9.8 to 12.4 g (Hoyt 1957); mean of 10.0ñ0.20 g (SD) (Harris 1982).
Color. White, semiglossy; shell translucent.
Clutch size. Historical records show clutch of 4 is most common (range = 1 6) with a mean of 3.83 (n = 99; WFVZ).
Egg-laying Begins after cavity is completed. One egg laid/d. During egg-laying, female spends long periods of time at the nest, preening, perched at entrance, tapping on walls, and quietly sitting inside (Harris 1982). Hoyt (1948a) observed a female enter nest (presumably to lay egg) and leave about 1.5 h later for rest of day; male was in cavity at night. If eggs are removed, female usually lays again, sometimes in same nest (New York; Hoyt 1957). Stockard (1904) found no evidence that Mississippi birds laid a second clutch after the first was taken. Intraspecific egg dumping not reported.
INCUBATION
Onset of broodiness and incubation in relation to laying. Incubation often starts before the last egg has been laid (Bull and Meslow 1988, JAJ). Birds are secretive during incubation.
Incubation patch. Present on both parents.
Incubation period. Stated as 18 d by several authors, beginning apparently with Bendire (1895; see Burns 1915, Hoyt 1944, Harris 1982), and as 15 16 d by Kilham (1979). Data presented on incubation period are sparse. Considering that the closely related Black Woodpecker is stated to have an incubation period of 12 14 d (Cramp 1985), we feel that further study is warranted.
Parental behavior. Roles and attention to eggs and incubating mate. Both parents incubate eggs alternately during day; male incubates at night. Eggs are attended 99% of time (Bull and Meslow 1988). Kilham (1979) reported that eggs were unattended for up to 20 min in first few days; attended nearly 100% of time after that. Truslow (1966) observed a Pileated Woodpecker carrying its eggs in its bill after the nest cavity broke open when the tree top fell over (destination not known).
Incubation rhythm, duration of attentive periods. During 44 h of observation at 3 nests in ne. Oregon, female arrived 22 35 min after sunrise, and birds changed an average of every 145 min (range = 43 259 min; Bull and Meslow 1988). Hoyt (1957) reported that male spent more time incubating in New York.
Change-over activities. Incubating bird typically remains in cavity until mate flies to nest, passes its head across the entrance hole, and moves aside to let the incubating bird out (Bull and Meslow 1988). Some exchanges are silent, in others both birds "cluck"; occasionally a bird in cavity drums (R. Dixon pers. comm.). Hoyt (1957) reported that the mate frequently called before coming to nest, then bird in nest often looked out and gave soft nasal chuck call; when mate flew to nest, bird inside rapped several times, then flew out as mate approached nest; mate entered cavity and often came up to entrance to look around before disappearing back into cavity.
HATCHING
Difficult to observe and not well known. Apparently asynchronous (Harris 1982). Eggshells are often left in cavity, eventually ground up and mixed with chips; addled egg disappeared from cavity after 9 d (Hoyt 1957). Harris (1982) reported that most of eggshell fragments were not in cavity within 4 d of hatching.
YOUNG BIRDS
Condition at hatching. Hatchlings are naked and helpless; remains of yolk sack are still attached to abdomen; eyes are covered with membrane with no evidence of slits; auricular openings are just beginning to develop; maxilla is shorter than and nested in the mandible, both tipped with egg tooth; large, fleshy rictal flanges at corners of beak; make squeaky hissing noise (Hoyt 1944, Harris 1982). Hoyt (1944) found newly hatched chicks in New York to weigh < 15 g.
Growth and development. See Hoyt 1940, 1944 for detailed study of nestling development in New York, and Harris 1982 for study of development in California.
Mass increase. In New York, chick weight 28.9 g on day 1; 41.2 g on day 2; 51.0 g on day 3; 67.1 g on day 4; 79.1 g on day 5; 98.9 g on day 6; 135.2 g on day 8; 165.2 g on day 10; 185.5 g on day 12; 209.2 g on day 16; 225.6 g on day 21 (Hoyt 1944; n = 3). Increase is rapid for first 13 d, then slows, until weight maximized by day 21 (Harris 1982).
Growth of body parts. Tarsometatarsus, hallux, and ulna reach nearly adult dimensions by day 9. Body length and wing chord show rapid growth; growth slows in second week at time of feather eruptions. Culmen growth is linear, reaches 75% of adult size by fledging. Maxilla is slightly longer than mandible by day 16; becomes dark gray by day 26. Auricular openings are evident by day 3; folds develop around ears on day 7; feathers cover ears by day 23. Trace of line across eyelid on day 3; eyes open on day 9. Hoyt (1940) provides excellent descriptions and photographs detailing development; detailed descriptions by Harris (1982).
Molt into Juvenal plumage. Nestlings have thickened papillae in most feather tracts on day 3. Remiges and rectrices erupt on day 5. Most body feathers erupt by day 7. Feathers of capital region erupt on day 11. Red malar stripe of male is evident by day 14. Sheaths slough off all wing-coverts by day 26 and off some of capitals and spinals by day 29. Detailed by Hoyt (1940) and Harris (1982).
Control of body temperature. Unknown, but brooding ceases after about 10 days.
Behavior. Newly hatched young give rasping begging call when hungry. Hunger rasps become stronger, and nestlings sound like beehive by day 3. By days 14 15, nestlings give churring sounds and a new adult-type vocalization sounding like a-nah. By days 16 19, a cuk note can be heard; nestlings perch at entrance hole by days 20 23 and watch for parent. When parent arrives, young raise crest, rasp loudly, and jab at parent with bill; give series of yuk calls. Descriptions by Harris (1982).
Locomotion. Newly hatched young are able to lift heads and open beaks. Can raise themselves on legs and flex their toes by day 5. Can climb up sides of cavity by day 11 13. Can reach cavity entrance by day 16 19. In days prior to leaving nest, young vocalize, flex wings, and teeter on rim of nest hole. Descriptions by Harris (1982).
PARENTAL CARE
Brooding. Parents brood nestlings when <7 10 d old; male broods more than female during day. Male returns to nest 1 149 min before sunset to brood young for night (Bull and Meslow 1988).
Feeding. Kilham (1979) and Bull and Meslow (1988) reported that both sexes fed young equally; Conway (1957) found female fed more. Young are fed about every hour when small, but interval increases to every 2 h after about 1 wk (Hoyt 1957). During 187 h of observation at 11 nests, young fed an average of every 52 min (range = 2 240 min; Bull and Meslow 1988).
Young are fed by regurgitation; adult inserts bill into throat of young; young sucks and jerks its head while parent regurgitates (Hoyt 1957). Young are fed primarily invertebrates. When nestlings are <7 10 d old, adult enters cavity completely to feed; nestlings 7 15 d old are fed by adult partially in cavity with tail sticking out of cavity; nestlings >15 18 d old wait for adults at cavity entrance and are fed from outside cavity (Bull and Meslow 1988). At 4 nests where female was killed when young were >10 d old, male raised ò1 young at each nest by himself; a male at one nest was killed, and the female abandoned (ELB).
Nest sanitation. Parents carry fecal sacs away from nest in bill (ELB). May eat feces for first few days (Short 1982). Cease removing fecal sacs 2 5 d before fledging (Harris 1982, ELB). Dead young are removed from nest if light enough for adult to carry (ELB).
Parental carrying of young. On 2 occasions, adult seen carrying small dead nestling in bill as it flew from nest; larger dead nestlings found under nest; nestlings >15 d old found dead in nest (ELB).
COOPERATIVE BREEDING
Not reported.
BROOD PARASITISM
Hoyt (1948a) reported that European Starling laid 1 egg in a Pileated Woodpecker nest; egg hatched when woodpecker eggs hatched, but starling nestling disappeared after 1 d.
FLEDGLING STAGE
Departure from the nest. Some fledglings are capable of sustained flight when leaving nest, others take several days; older nestlings frequently leave cavity if nest tree is climbed (ELB). Nest mates depart as much as 3 d apart (Harris 1982).
Age at departure. 24 28 d in ne. Oregon (Bull and Meslow 1988); 26 28 d in New York (Hoyt 1957); 26 31 d in California (Harris 1982); approximately 30 d in Kentucky (Mengel 1965).
Condition of development at departure. Flight feathers are about 75% of adult size at nest departure (Harris 1982). Flight and movements of recently fledged young typically are awkward and weak (R. Dixon pers. comm.). Hoyt (1948b) found weights of New York young just prior to fledging to range from 218.7 to 244.4 g at one nest and 211.21 to 223.2 g at another.
Association with parents or other young. Initially parents and siblings stay in same vicinity. Once young can fly well, they follow adults everywhere. All young may stay with both parents, or parents may split up and each take some of young (ELB). Young depend on parents for several months (until at least Sep) to provide food and teach them to acquire food.
IMMATURE STAGE
Young leave parents in fall and seem to wander until spring when they will nest if a mate and territory are acquired. Two young in ne. Oregon ranged up to 6 km from natal site in their first winter (ELB).
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