1 May 2001
Prepared by: Kerry Farris, Wildlife Conservation Society, (520) 881-5836, p_arcticus@yahoo.com
Reviewed by: Steve Zack,. May 22, 2001
SPECIES: Black-backed Woodpecker (Picoides arcticus)
SUBSPECIES STATUS
No formal subspecies recognized.
MANAGEMENT STATUS
No special status. Protected under the Migratory Bird Treaty Act.
RANGE IN CALIFORNIA
1. Historical References
Grinnell and Miller (1944) described the range of P. arcticus to be, “Chiefly Cascade Mountains and high northern and central Sierra Nevada, south to Tulare County; peripherally west through the Siskiyou Mountains, east to Warner Mountains, Modoc County. Altitudes of recorded occurrence 4,000 to 10,168 feet.”
2. Current Breeding Distribution
The current range of the Black-backed Woodpecker in California extends from the Siskiyou and Warner Mountains at the Oregon border and extends south along the Cascade and Sierra Mountains to eastern Tulare County in the south (Small 1994).
ECOLOGY
1. Average Territory Size
Information on home range size is lacking for this species, and there are no accounts for California. Documented home range sizes vary from and average of 61ha in the forests of Vermont (Lisi 1988) to a median of 124 ha. in central Oregon (Goggans et al. 1988).
2. Time of Occurrence and Seasonal Movements
The Black-backed Woodpecker is generally a non-migratory resident species and therefore has no predictable seasonal movements.
3. Nest Type
Excavation of the nest cavity typically begins during April or May (Dixon and Saab 2000), but may start as late as June in colder climates (Bull 1980). Both sexes participate in nest construction, however it is likely the male does most of the work (Short 1974; Goggans et al. 1988).
4. Foraging Strategy
Primarily feeds on the larvae of wood-boring beetles of the families Cerambycidae and Buprestidae by excavating into the trunks of standing dead trees (Bent 1939; Harris 1982; Villard and Beninger 1993; Murphy and Lehnhausen 1998). Also takes bark beetles of the family Scolytidae (Kilham 1965; Goggans et al 1988). Beal (1911) reported that individuals captured 85% of their prey by pecking, 10% by gleaning, and 5% by ground foraging. In Montana, Jackman (1975) reported Black-backed Woodpeckers primarily pecking (80%), while using scaling and probing in much smaller proportions. Murphy and Lehnhausen (1988) reported almost exclusive use of the excavation strategy in Alaska and Canada. In northeast Oregon, this species scaled 72% of the time, with pecking and gleaning making up the remainder of the foraging time budget (Bull et al. 1986). In the southern Cascades of Lassen County, California, this species spent 41% of the time excavating, 34% pecking, 23% scaling, and 2% probing (Farris unpub. data).
5. Displays
a) Drumming – Both sexes drum throughout the year, however this activity is most prevalent during the breeding season (Dixon and Saab 2000) and serves to both advertise a territory and attract a mate (Dixon and Saab 2000).
b) Vocal Displays – This species has a wide array of unique vocalizations, including an unusual and complex rattle-like snarl which is often used in antagonistic encounters between conspecifics (Dixon and Saab 2000).
c) Physical Displays – These include bill positioning, head swinging, crest-raising, wing-spreading, and fluttering flight (Short 1974). These displays are used in wide range of communications from inter-pair contact to antagonistic encounters between conspecifics or other species.
6. Mating System
Monogamous pair bond (Winkler et al. 1995).
7. Clutch Size
One clutch per season ranging in size from 2-6 (Bent 1939), but commonly 3-4 (Short 1982).
8. Incubating Sex
Both sexes share incubation duties, with males brooding throughout the night until late nestling period (Mayfield 1958; Short 1974).
9. Incubation Period
Incubation lasts approximately 12-14 days (Ehrlich et al. 1988).
10. Nestling Period
Young fledge after 24 –25 days (Dixon and Saab 2000; Ehrlich et al. 1988).
11. Development at Hatching
Altricial (Dixon and Saab 2000).
12. Number of Broods
Generally 1 per breeding season (Grinnel and Miller 1944), but is known to renest if clutch is lost (Dixon and Saab 2000; Harrison 1978).
13. Who Tends Young
Both sexes tend young (Dixon and Saab 2000; Ehrlich et al. 1988).
HABITAT
1. Nest Site
a) Nest Substrate – Nests in both snags and live trees of several species. In southwest Idaho, nests were in burned ponderosa pine and Douglas-fir (Dixon and Saab 2000), but are also documented in quaking aspen, paper birch, western larch, red maple, jack pine, lodgepole pine, black spruce, white spruce, balsm-fir, noble fir, red fir, and silver fir. In the northern Sierra Nevada, Raphael and White (1984) reported nests in lodgepole pine, red fir, and Jeffrey pine in early stages of decay.
b) Nest Height – Nest heights range from 8.5 meters in Wyoming (Hoffman 1997) to 19 meters in northeastern Oregon (Bull et al. 1986).
c) Substrate Size – Reported substrate diameters outside California range from 27 centimeters in Wyoming (Hoffman 1997) to 40 centimeters in Montana (Caton 1996). In the northern Sierra Nevada, Black-backed woodpeckers nested in 45 cm snags (Raphael and White 1984). Substrate heights range from 17 meters in California (Raphael and White 1984) to 33 meters in Wyoming (Hoffman 1997).
d) Nest Concealment – No information.
e) Percent Nest Cover – Information lacking, but it is generally assumed that this species prefers to nest in microsites with relatively high tree/snag densities (Dixon and Saab 2000).
2. Vegetation Surrounding the Nest
a) Canopy Cover – No detailed information available.
b) Average Top Canopy Height – See substrate size above.
c) Dominant Plant Species in Canopy – Variable. In California, Raphael and White (1984) documented use of Jeffrey pine, white-fir, and red-fir.
d) Aspect – Variable (Dixon and Saab 2000).
e) Tree DBH – See “Substrate Size” above.
f) Snags, Stumps and Logs – Generally uses snags for nesting (see “Nest Substrate” above). Grinnel and Miller (1944) reported the use of stumps. No information on logs.
g) Distance to Water – No information available.
3. Landscape Factors
a) Elevation -- Altitudes of recorded occurrence, 4,000 to 10,168 feet.
b) Fragmentation – Many studies cite habitat fragmentation, in the form of timber harvest as a major threat to this species (Dixon and Saab 2000), however few have directly evaluated the effects.
c) Patch Size – See “Average Territory Size” above.
d) Disturbance – This species is strongly associated with natural perturbations such as wildfire, insect outbreaks, and windthrow.
e) Adjacent Land Use – Adjacent land use which contributes to significant habitat degradation and/or fragmentation likely detrimental to this species.
f) Climate – Black-backed are typically found in climates which support relatively mesic mixed coniferous forests in the northern portions of its range, and relatively xeric conifer forests in the southern portions (e.g. ponderosa/Jeffrey pine forests in CA).
4. Special Factors
a) Brood Parasitism – None reported
b) Dietary – The dietary needs of this species are dependant upon naturally
caused perturbations which are often deemed undesirable by humans.
Consequently,
large scale, intensive forest management strategies which emphasize
the removal of dead and dying trees are likely detrimental to the Black-backed
Woodpecker’s survival.
5. Sensitivity to Human-Induced Disturbance
Specific information is lacking in this area. However, due to
its strong association with natural perturbations, which produce both its
prey and nesting habitat, this
species is likely sensitive to human-induced disturbances which alter
the natural cycles of wildfire and both native forest insects and pathogens.
Several authors have cited logging and fire suppression to be the major
threats to this species, but specific data supporting these theories are
lacking; especially in California.
6. Pesticide
No information.
7. Predators
Specific information lacking. However, there has been documented predation by Cooper’s Hawks (Dixon and Saab 2000). In Oregon, Goggans et al. 1988) suspected egg predation by chickarees (Tamiasciurus douglasi).
8. Exotic Species Invasion/Encroachment
No information.
9. Population Trend
The population trend for the Black-backed Woodpecker in California is
increasing at a rate of 9.6% per year (p < 0.02, n = 5). However,
the U.S. Fish and
Wildlife Service Breeding Bird Survey rates these data as poor in credibility
standards for the following reasons (Sauer et al. 1999): 1) the regional
abundance of
this species is less than 0.1 birds/route; 2) the sample is based on
less than 5 long term routes; 3) the results are so imprecise that a 5%
per year change would not be detected over the long term.
10. Demographics
Bent (1939) reported a clutch size between 2-6 for this species with average of 3-4 reported by Short (1982). One clutch per season, but have been documented to renest if first clutch is lost (Harrison 1978). Annual lifetime reproductive success ranges between 1.6 young/successful pair in Wyoming to 1.8 young/successful pair in southwest Idaho (Dixon and Saab 2000). There is no information on the age at first breeding for this species.
11. Management Issues
Due to the paucity of information regarding the explicit habitat requirements of Black-backed Woodpeckers, outlining a specific set of habitat management goal is problematic. However, considering this species’ strong association with habitat parameters created by natural perturbations (e.g. snags and associated insect prey), it is likely that the Black-backed Woodpecker would benefit from management strategies that emphasize the conservation of ecological processes associated with native disturbance regimes (e.g. wildfire and cyclic populations of native forest insects and pathogens). Traditional management practices that focus solely on snag density targets for a given area may meet short term objectives, but they may fail to promote the dynamic creation and long-term maintenance of snag populations. A more holistic approach that maintains ecological processes responsible for various snag decay pathways and successional stages could potentially provide a greater temporal and spatial distribution of snags and associated woodpecker habitats.
12. Associated Bird Species
Often associated with other Picoides woodpeckers; especially when large concentrations gather in recent burns. In California, the Black-backed woodpecker is generally associated with both the Hairy and White-headed woodpeckers.
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