22 November 2000
Prepared by: John C. Robinson, USDA Forest Service, 1323 Club Drive, Vallejo, CA 94592 (707) 562-8929
SPECIES: Pileated Woodpecker (Dryocopus pileatus)
Action Plan Summary
Four subspecies of Pileated Woodpecker were recognized by Bent (1939) and also by the American Ornithologists’ Union (1957):
It has been suggested by some scientists that the Pileated Woodpecker,
the Lineated Woodpecker (Dryocopus lineatus) and the Black-bodied
Woodpecker (D. schulzi) of South America may, together, constitute
a superspecies (AOU 1998, Bull and Jackson 1995).
No special status. Protected under the Migratory Bird Treaty Act.
RANGE IN CALIFORNIA
1. Historical References
Grinnell and Miller (1944) considered old records of the Pileated Woodpecker in San Benito County and near Mount Diablo in Contra Costa County to possibly represent former or sporadic occurrences of this species south of its then present range in the coast belt of California.
2. Current Breeding Distribution
The California range of the Pileated Woodpecker extends from the Oregon line in Siskiyou County, south in the Coast Range region to Sonoma, Marin, Santa Cruz and western Santa Clara Counties, and to Howell Mountain in Napa County. Further inland, its range extends from the Mount Shasta and Lassen Peak areas south throughout the Sierra Nevada to the Greenhorn Mountains in Tulare and Kern Counties (AOU 1998; Grinnell and Miller 1944; Small 1994). Small (1994) also mentions recent occurrences of this species in Alameda and Contra Costa Counties, but provides no additional details. Although Grinnell and Miller (1944) considered it to be a fairly common resident, Small (1994) described it as a rare to uncommon resident.
1. Average Territory Size
Schroeder (1982) summarized interspersion requirements and minimum size of forest needed by the Pileated Woodpecker. In general, the availability of food will, to some degree, affect the minimum territory size of Pileated Woodpeckers. Moreover, there is an inverse relationship between home range size and log volume, stump volume, and canopy closure (Bull and Jackson 1995). The Habitat Suitability Index Model presented by Schroder (1982) assumes that a minimum of 320 acres of habitat must exist to meet the needs of the Pileated Woodpecker; some of the studies cited in the model document nesting pairs of Pileated Woodpeckers ranging over areas as large as 600 acres. Average home range sizes of pairs in northeastern Oregon and western Oregon ranged from 1006 acres to 1181 acres, respectively (Bull and Jackson 1995).
2. Time of Occurrence and Seasonal Movements
Because the Pileated Woodpecker is, for the most part, a non-migratory species, information specific to migration and arrival on (or departure from) breeding grounds will not be presented as such subjects are more appropriate to discuss for migratory bird species. Pileated Woodpeckers generally initiate nest hole excavation during late February or March, but sometimes as late as May; it generally takes the birds about 30 days to complete the construction of the nest (Bull and Jackson 1995; Terres 1980). Eggs of the Western Pileated Woodpecker are apparently not laid until sometime between late April and mid-May, and occasionally as late as the third week in June (Bent 1939a; Bull and Jackson 1995; Terres 1980).
3. Nest Type
The Pileated Woodpecker constructs a cavity for nesting. The nest cavity is excavated by both sexes, and is usually located in a dead tree or the dead portion of a live tree.
4. Foraging Strategy
Primarily feeds on animal foods, especially carpenter ants (Camponotus spp.). Foraging strategies include gleaning (from branches, trunks, and logs); pecking or chiseling out chips of wood or holes in trees; and scaling, excavating, or stripping off the bark of dead trees to locate ants and beetles. In addition to standing trees and snags, Pileated Woodpeckers may forage on short stumps or rotten logs lying on the ground; they are also known to dig into anthills in search of prey. Pileated Woodpeckers also feed on acorns, beechnuts, wild grapes, a variety of plant seeds and fruits, and various insects, including flies, mosquitoes, wood-boring beetle larvae, and moths (Bull and Jackson 1995; Terres 1980). In Oregon, foraging activity is predominantly (>80%) concentrated on dead snags, down logs, or stumps (Bull and Jackson 1995).
Like most woodpeckers, the Pileated Woodpecker drums by forcefully rapping its bill on a tree or other resounding object. Drumming functions as a communication tool among woodpeckers, and serves to both attract a mate as well as for territorial defense. Although both sexes of this species drum, the male does so more than the female (Terres 1980). This non-vocal sound consists of 11-30 beats per burst, and each burst may last between 0.7 and 3 seconds (Bull and Jackson 1995). Most skilled ornithologists can recognize the drumming of the Pileated Woodpecker by the sheer depth and volume of the drumming sound.
6. Mating System
Pileated Woodpeckers utilize a monogamous mating strategy (Ehrlich et al. 1988). The pair bond of the Pileated Woodpecker is stronger than any other North American woodpecker (they presumably mate for life), and pairs appear to occupy the same territory from one year to the next; a new nest cavity is excavated by the pair each spring, which is one of the reasons why a constant supply of snags is needed by this species (Bull and Jackson 1995; Schroeder 1982).
7. Clutch Size
Between one and eight eggs may be laid, although the average number ranges from 3-5 (Bull and Jackson 1995; Ehrlich et al. 1988; and Terres 1980). Bent (1939a) reported that he had no records of clutch sizes larger than three or four eggs for the Western Pileated Woodpecker.
8. Incubating Sex (Female/Male)
Both sexes incubate the eggs and care for the young (Ehrlich et al. 1988; Terres 1980). Incubation has usually been initiated before the last egg of the clutch has been laid (Bull and Jackson 1995).
9. Incubation Period
Incubation period lasts approximately 15-18 days (Ehrlich et al. 1988; Terres 1980). Bull and Jackson (1995), however, feel that more study is needed to more accurately define the incubation period. Incubation is performed by both parents.
10. Nestling Period
Young leave the nest and/or are capable of flight when they are about 26-28 days old (Ehrlich et al. 1988). Bull and Jackson (1995) report young leaving the nest as early as 24 days old in Oregon and as late as 31 days old in California.
11. Development at Hatching
Young are altricial.
12. Number of Broods
Pileated Woodpeckers produce no more than one brood per year (Ehrlich et al. 1988); birds may renest upon failure of the first nesting attempt (Bull and Jackson 1995).
13. Who Tends Young
Although both sexes incubate the eggs and care for the young, it has been reported that the male has a greater role in the incubation process since he incubates part of the day as well as at night (Ehrlich et al. 1988; Terres 1980). After the young have hatched, adult males also brood the nestlings at night (Terres 1980). Young may be dependent on their parents for food until August or September (Bull and Jackson 1995).
1. Nest Site
a. Nest Substrate
In California, Grinnell and Miller (1944) reported that the Pileated Woodpecker uses coniferous habitats, particularly those forests with some standing dead and decaying trees; they specifically mentioned that this species uses dead conifers and large aspens (Populus) for nesting purposes. The cavity is usually placed in a dead tree, or in the dead branch of a live tree. Throughout its range, other species of tree which may be selected for nesting include: beech (Fagus), poplar (Populus), tulip tree (Liriodendron tulipifera), birches (Betula), oaks (Quercus), hickories (Carya), maples (Acer), hemlocks (Tsuga), pines (Pinus), ash (Fraxinus), elms (Ulmus), basswood (Tilia), cypress (Cupressus), sycamore (Platanus), sweet gum (Liquidambar styraciflua), hackberry (Celtis), grand fir (Abies grandis), Pacific silver fir (Abies amabilis), or red alder (Alnus rubra) (Bull and Jackson 1995; and Terres 1980). Other nest tree species may include Douglas-fir (Pseudotsuga taxifolia) and western larch (Larix occidentalis) (The Nature Conservancy 1999). In northeastern Oregon, about 78 of 105 nest trees were ponderosa pine, and 80% of all nests in western Oregon were excavated in live or dead Douglas fir trees (Bull and Jackson 1995).
b. Height of Nest
The nest of the Pileated Woodpecker is generally 15 to 45 or more feet above the ground (Ehrlich et al. 1988; Terres 1980). In Oregon and Washington, the mean height of the nest hole ranged from 49-125 feet above the ground (Bull and Jackson 1995).
c. Height or Size of Nest Plant
There is wide variance in both nest tree species and the size of the tree that is used for nesting by Pileated Woodpeckers. Representative sizes of trees selected for nesting in the western U.S. range from 40 cm (16 in.) dbh aspen trees in southern British Columbia to 97 cm (38 in.) dbh trees in western Washington (Bull and Jackson 1995; and The Nature Conservancy 1999). Nest tree heights in the western U.S. have been reported to be as tall as 28-41 m (92-135 feet) (Bull and Jackson 1995; and Schroeder 1982).
d. Plant Species Concealing Nest
See "Nest Substrate" above.
e. Percent Nest Cover
Because the nests are placed in a tree cavity, they are largely concealed from potential predators.
2. Vegetation Surrounding the Nest
a. Canopy Cover
The Pileated Woodpecker prefers woodlands that have a tall, closed canopy and a high basal area; in the western and northwestern parts of its range, it favors dense coniferous forests, but will also use mixed forests, open woodland, second growth, and in certain situations may also frequent parks and wooded residential areas of towns (The Nature Conservancy 1999). Isolated large, dead trees amidst a younger forest may also be used for nesting (Bull and Jackson 1995). Shroeder (1982) assumed that optimum habitats for Pileated Woodpeckers contain canopy closures of 75% or greater; and that stands with less than 25% canopy closure have no suitability for the species.
b. Average Top Canopy Height
Schroeder (1982) summarized two studies in the western United States, both of which reported the mean height of the nest tree as 28 m (92 feet). Bull and Jackson (1995) have documented nest tree heights as large as 135 feet.
c. Dominant Plant Species in Canopy
Nest tree species frequently chosen by the Pileated Woodpecker in Oregon include ponderosa pine and Douglas fir. See also Nest Substrate, above.
Over 70% of nest cavities in northeastern Oregon faced between a northeasterly and southwesterly direction (Bull and Jackson 1995).
e. Tree DBH
As mentioned above, representative sizes of trees selected for nesting in the western U.S. range from 40 cm (16 in.) dbh to 97 cm (38 in.) dbh. Schroeder (1982) cited three studies in western North America that reported the mean dbh of nest trees ranging from 74.9 to 78 cm (29.5-30.1 in.); and his model assumes that optimum Pileated Woodpecker habitat contains 30 or more trees greater than 51 cm dbh per 0.4 ha (20 inches dbh/acre). Mean dbh of trees in Washington and Oregon reported by Bull and Jackson (1995) ranged from 27.2 inches to 38.2 inches.
f. Snags, Stumps and Logs
Pileated Woodpeckers use at least four cavities each year, with only one of these being used for nesting purposes (The Nature Conservancy 1999). Because of their foraging, nesting, and drumming habits, Pileated Woodpeckers depend on habitats that have an abundance of standing live, dead, or dying trees, snags, and stumps. Habitats with high densities of down logs and snags are preferred. Schroeder (1982) summarizes one Oregon study where Pileated Woodpeckers spent 36% of their feeding time foraging on logs, 35% on live trees, and 29% on snags. Typically, the male and female each digs and uses its own roosting cavity (Terres 1980), which may be separate from the cavity used by the pair for nesting. Over a 10-month period, individual birds may utilize an average of seven (range 4-11) different trees for roosting purposes (Bull and Jackson 1995). The number of snags needed to support maximum Pileated Woodpecker populations have been estimated by several researchers and include the following recommendations (Schroeder 1982): 18-26" dbh snags at a density of 0.24 snags/acre; snags greater than 20" dbh at a density of 0.14 snags per acre; and snags greater than 20" dbh at a density of 0.13 snags per acre. Shroeder's (1982) habitat model assumes that optimum or maximum Pileated Woodpecker habitat contain 30 or more trees greater than 20" dbh per acre; 10 or more logs greater than 7" diameter and/or stumps of the same diameter and greater than 1 foot high per acre; 0.17 or more snags per acre, where a snag is defined as greater than 20" dbh. Conditions are considered to be best when the average dbh of all snags greater than 20" is 30".
g. Distance to Water
In one study, Pileated Woodpeckers were found to nest no farther than 150 m (492 feet) from water, with most nests within 50 m (164 feet) of water (Schroeder 1982).
3. Landscape Factors
This species has been documented in California at elevations as low as 500 feet and as high as 7500 feet (Grinnell and Miller 1944).
Grinnell and Miller (1944) reported that this species' range in California was diminishing in response to the expanding operations of the logging industry. Bull and Jackson (1995) suggested that fragmentation of forested habitats could reduce population densities and make birds more vulnerable to predation.
c. Patch Size
See Average Territory Size, above.
d. Disturbance (Natural or Managed)
See Sensitivity to Human-Induced Distubance, below.
e. Adjacent Land Use
Because of this woodpecker's preference for extensive forested areas, any adjacent land uses that would increase fragmentation of the landscape and further isolate remnant tracts of forest lands may negatively impact the species.
Pileated Woodpeckers are typically found in mesic environments where rainfall amounts are sufficient to produce the large trees that they prefer.
4. Special Factors
a. Brood Parasitism
See Foraging Strategy, above.
5. Sensitivity to Human-Induced Disturbance
Grinnell and Miller (1944) summarized the status of this species as "diminishing about commensurately with extension of lumbering operations." Although it prefers dense, mature forests, it will adapt to second-growth forests and Bent (1939b) summarizes written accounts of it reappearing in places in the northeastern portions of its range where it had been absent for many years. It has increased in numbers where forests have reclaimed abandoned farmlands; increases in population numbers may also be attributable to the large die-off of American elms (due to Dutch elm disease), which resulted in an increase in food prey items and potential nesting and roosting sites (The Nature Conservancy 1999). However, it is generally considered to be less common throughout its California range than it is in the northeastern United States.
Threats considered to be most important to this species include (The Nature Conservancy 1999): conversion of forest habitats to non-forested habitats; short-rotation, even-age forestry management; monoculture forestry; forest fragmentation; and removal of logging residue and downed wood from the forest floor. In particular, the removal of logging residue and downed wood takes away the nutrients and foraging substrates for Pileated Woodpeckers and also reduces the overall water content of the forest floor, making it less suitable for the arthropod fauna that this species is dependent on.
Some birds are more sensitive to disturbance at the nest/roost site than are other birds, and they may change the location of their roost tree in response to human disturbance. This species was also regularly shot and/or trapped by sport hunters in the early 20th century. Although such activities are no longer legal, birds continue to be shot even today (Bull and Jackson 1995). Compared to other species, Pileated Woodpeckers are also noticeably more susceptible to mortality resulting from collisions with vehicles – this, due to their habit of feeding on or near the ground (Ibid. 1995).
As with most species, toxic chemicals can affect the Pileated Woodpecker via direct poisoning or indirectly by the killing of its arthropod prey species. Improper use of agricultural chemicals or widespread pesticide programs aimed at controlling fire ants, for example, can cause both of these effects (The Nature Conservancy 1999). Creosote in utility poles that are used for nests may also cause mortality of eggs and nestlings (Bull and Jackson 1995).
Potential predators include rat snakes (Elaphe obsoleta), Accipiter hawks, and gray fox (Urocyon cinereoargenteus) (The Nature Conservancy 1999). Other known predators include Red-tailed Hawk (Buteo jamaicensis), Great Horned Owl (Bubo virginianus), American marten (Martes americana), weasels (Mustela spp.), and squirrels (Bull and Jackson 1995).
8. Exotic Species Invasion/Encroachment
No information found.
9. Population Trend
The national population of Pileated Woodpeckers, as reported by the U.S. Fish and Wildlife Service's Breeding Bird Survey data (1966-1999), is significantly increasing at a rate of 1.4% per year (P value of 0.0); in California, Pileated Woodpeckers are increasing non-significantly (P value of 0.66) at a rate of 0.4% per year (Sauer et al. 1999). Density estimates range from one pair per 160-220 ha. (395-544 acres) in California to one nesting pair per 356 ha. (879 acres) in northeast Oregon (Bull and Jackson 1995).
Pileated Woodpeckers breed at age 1. Mean annual adult survival over an 8-year period in northeast Oregon was 64% with a 35.40 % standard deviation (Bull and Jackson 1995). Pileated Woodpeckers may live for up to nine years. To date, there are no estimates of the minimum viable population size for this species (The Nature Conservancy 1999).
11. Management and Habitat/Population Issues
Bull and Jackson (1995), Shroeder (1982), and The Nature Conservancy (1999) inform much of the discussion in this section of the conservation plan. The Pileated Woodpecker is both a long-lived and a wide-ranging species. When combined, these two factors add an additional layer of complexity to management planning options that may be designed for this species. For example, adverse effects to its habitat could occur many years before we witness a corresponding decline in the Pileated Woodpecker’s populations at various geographic scales. Moreover, by the time population declines have been documented, it is not clear how many more years would be needed to pinpoint the cause of such declines and implement measures to reverse those trends.
The focus of habitat management for the Pileated Woodpecker in the western
United States should concentrate on riparian forested habitats along rivers
and large streams; and on the western (more humid) slopes of mountains,
where food and nest habitat attributes are most plentiful. The goal of
management for this species is to maintain the current population stability
of this species while looking for opportunities for localized population
increases. Management options that are recommended for this species include:
a. Forest Harvest Rotations
Cutting rotations of 80-150 years have been suggested as necessary to maintain foraging and nesting habitat in the eastern United States and should, at a minimum, be adopted in the west as well. Note: in many areas of the west, even longer rotations than those recommended here may be desirable.
b. Baseline Conservation Recommendations
c. Management Areas – Within specific breeding areas managed for Pileated Woodpeckers:
- Maintain wooded areas in which dead and dying trees are allowed to remain.
- Retain dead or dying stubs of some live trees.
- Retain dying trees in open areas of parkland, golf courses, and woodland.
- Manage wet forests to allow decay of rotting trees.
- Utilize selective cutting silvicultural techniques rather than clear cutting of managed forests.d. Monitoring – to be accomplished at two levels:
Manage forests to provide for home range habitat needs across areas ranging in size from 600-900 acres. Over half of the forested landscape in each Management Areas should have canopy cover of 60% or greater. Leave three or more snags per acre (where a snag is 20" or greater at d.b.h.) within each Management Area.In the course of looking for opportunities where the above management recommendations may be met, it will be important to also identify where and when the threats to this species (see outline section 5, above) exist and can be mitigated. Population monitoring, utilizing techniques such as banding and recapture studies, telemetry studies, and other censuses. Habitat monitoring, both within and across regions.
12. Associated Bird Species
The Pileated Woodpecker has been identified in some areas as a management indicator species for old-growth forests. In the western U.S., including other California species which utilize old-growth forests include the Spotted Owl (Strix occidentalis), Northern Goshawk (Accipiter gentilis), and Marbled Murrelet (Brachyramphus marmoratus).
American Ornithologists’ Union. 1957. Check-list of North American Birds. 5th edition. Port City Press Inc., Baltimore, MD. 691 p.
American Ornithologists' Union. 1998. Check-list of North American Birds. 7th edition. American Ornithologists' Union. Washington, D.C. 829 pp.
Bent, A. C. 1939. CEOPHLOEUS PILEATUS PILEATUS (Linnaeus). Southern Pileated Woodpecker. Pages 164-171 in A. C. Bent. Life histories of North American woodpeckers. U.S. National Museum Bulletin, No. 174.
Bent, A. C. 1939a. CEOPHLOEUS PILEATUS PICINUS (Bangs). Western Pileated Woodpecker. Pages 191-194 in A. C. Bent. Life histories of North American woodpeckers. U.S. National Museum Bulletin, No. 174.
Bent, A. C. 1939b. CEOPHLOEUS PILEATUS ABIETICOLA Bangs. Northern Pileated Woodpecker. Pages 171-189 in A. C. Bent. Life histories of North American woodpeckers. U.S. National Museum Bulletin, No. 174.
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Grinnell, J. and A.H. Miller. 1944. The distribution of birds of California. Pacific Coast Avifauna Number 27, 608 pp.
Nature Conservancy, The. 1999. Pileated Woodpecker (Dryocopus pileatus) in Wings Info Resources/Species Information and Management Abstracts, Wings of the Americas. Internet: www.tnc.org/wings/wingresource/piwo.html.
Sauer, J.R., J.E. Hines, I. Thomas, J. Fallon, and G. Gough. 1999. The North American Breeding Bird Survey, Results and Analysis 1966-1998. Version 98.1, USGS Patuxent Wildlife Research Center, Laurel, MD.
Schroeder, R. L. 1982. Habitat suitability index models: Pileated Woodpecker. U.S. Dept. Int., Fish and Wildl. Serv. FWS/OBS-82/10/39. 15 pp.
Short, L.L. 1982. Woodpeckers of the world. Delaware Mus. Nat. Hist. Monogr. No. 4.
Small, A. 1994. California birds: their status and distribution. Ibis Publishing Company, Vista, CA. 342 pp.
Terres, J.K., ed. 1980. The Audubon Society Encyclopedia of North American
Birds. Alfred A. Knopf, Inc. New York. 1109 pp.
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