Restoration Potential: Still relatively abundant in appropriate habitats. Restoring and sustaining populations will require an ecological approach to management that incorporates a landscape perspective of the required habitat mosaic, the relationship to aspen (POPULUS spp.) and presence of shelf fungus (FOMES IGNIARIUS var. POPULINUS), and management to sustain and regenerate riparian and aspen woodlands.
Preserve Selection and Design Considerations: Apparently responds to a habitat mosaic that includes broad-leaved trees (e.g., aspen [POPULUS spp.], birch [BETULA spp.], cottonwood [POPULUS spp.]) for nesting and adjacent coniferous forest and/or willows (SALIX spp.) for foraging (Ehrlich and Daily 1988, Tobalske 1992, USDA Forest Service 1994). Known to use natural edges of mature mixed conifer and deciduous hardwood habitats (USDA Forest Service 1994). In one study, sapsuckers showed a significant correlation with stand area and the presence of adjacent hardwoods (Rosenberg and Raphael 1986). No significant sensitivity to patch size was observed in a study of Idaho cottonwood gallery forests, although birds were more often detected in large patches (more than 10-200 hectares; 0.21 birds per point count visit) than in small patches (less than 1-3 hectares; 0.12 birds per point count visit; Saab 1998).
Management Requirements: Sustaining populations requires maintaining, enhancing, and restoring snags, riparian woodlands, and hardwood stands of aspen (POPULUS spp.), birch (BETULA spp.), and cottonwood (POPULUS spp.) adjacent to coniferous forest.
FOREST MANAGEMENT: Both snags and live trees retained for the species should include a mix of hardwood and conifer species, particularly near riparian areas and mesic sites (USDA Forest Service 1994). Aspen and other trees with shelf fungus (FOMES IGNIARIUS var. POPULINUS) should be retained to provide optimal conditions for nest cavities. Access to conifer sap in adjacent forest is also important in the early spring, and to birches and aspens after bud-break (Tobalske 1992).
Thomas et al. (1979) estimated 25 centimeters was the minimum dbh required for a nest tree, and 4.6 meters the minimum cavity height. Nests have been reported in a wide range of tree sizes, from 9 to 47 centimeters dbh (Crockett and Hadow 1975, McClelland et al. 1979, Li and Martin 1991, Dobkin et al. 1995), with approximately 38 centimeter dbh the overall average.
Will use forest edges and logged forests, but extensive clearcuts or the removal of snags and preferred tree species would be detrimental. Also will use burns, partially-cut forests and small clearcuts where snags and live hardwood trees remain and adjacent forest is available for foraging (Bock and Lynch 1970, Tobalske 1992). In a western larch (LARIX OCCIDENTALIS) and Douglas-fir (PSEUDOTSUGA MENZIESII) forest in northwestern Montana, no significant difference in abundance or nest success was found between small partial cut and clearcut units (less than 16 hectares) and adjacent large tracts of unharvested even-aged forest. In cutting units, however, a large number of standing western larch snags and live paper birch (BETULA PAPYRIFERA) and aspen were retained (basal area of 1.8 to 8.0 square meters per hectare) and adjacent coniferous forest was available for feeding. The number of birch and aspen were equivalent in logged and unlogged stands, although canopy cover in logged stands was half that of unlogged stands (22 percent vs. 55 percent; Tobalske et al. 1991, Tobalske 1992). Assuming a linear relationship between sapsucker abundance and snag density, Bull (1978) recommended 150 snags greater than or equal to 25 centimeter dbh per 40 hectares to support maximum populations.
GRAZING: Mature riparian woodlands and regeneration of riparian trees have been heavily impacted by livestock throughout the West (Ohmart 1994). Grazing can have detrimental effects where the health and regeneration of aspen, cottonwood, and other preferred species is compromised. Studies of grazing impacts show mixed effects in the short term. In an Idaho cottonwood gallery forest where moderate to heavy grazing reduced understory shrub cover, Saab (1998) found no significant difference between grazed and unmanaged sites, although sapsucker abundances were slightly higher in unmanaged forest. Along one Colorado mountain stream, Schulz and Leninger (1991) observed sapsuckers only in grazed sites; however the authors indicated that aspen occurred in mesic upland areas but did not report the relationship between aspen cover and treatment. On a Nevada canyon stream, Medin and Clary (1991) found equal abundances in grazed and ungrazed sites, but the sites also showed no significant differences in percent forb cover, percent shrub cover, or in tree density.
On the other hand, in western Montana cottonwood/ponderosa pine (PINUS PONDEROSA) riparian habitat, were significantly more abundant on lightly grazed sites than on heavily grazed sites, where ground cover, bush cover, mid-canopy cover, and number of small trees (less than 10 centimeter dbh) were significantly reduced in the heavily grazed sites (Mosconi and Hutto 1982). In California/Nevada aspen habitat, Page et al. (1978, cited in Saab et al. 1995) also observed a negative response to grazing.
Management Research Needs: Management requirements have been little studied and there is ample opportunity to make significant contributions to the understanding of the species. Further study is needed of habitat relationships at multiple scales, and the effects of habitat alterations and management activities, particularly timber harvest, different grazing regimes, and fire. Better information is needed of nesting and foraging habitat relationships throughout the species range, and the species' relationship to the ecology and succession of hardwood and conifer woodlands. Landscape relationships, such as response to edge, fragmentation, patch size, and habitat juxtaposition are poorly known. Threats are largely unknown; regional assessments of the condition and trends in, aspen (POPULUS spp.), birch (BETULA spp.), and broad-leaved riparian cover types would help illuminate the threats to the species. Further understanding of interdependence of other species (e.g., shelf fungus) would provide an ecological perspective to management activities.
Biological Research Needs: Although this species is relatively common in appropriate habitats, its natural history has been little studied. Further research is needed on the distribution, migration, winter habitat use, and winter ecology. Its role as a keystone species deserves further study. Breeding biology, demographics, home range, territory size, site fidelity, dispersal, predators and competitors are poorly known.