APPENDIX K HABITAT NEEDS: THE PILEATED WOODPECKER AND OTHER PRIMARY CAVITY EXCAVATORS

Transcription

1 APPENDIX K HABITAT NEEDS: THE PILEATED WOODPECKER AND OTHER PRIMARY CAVITY EXCAVATORS Habitat Needs

2 Pileated The pileated woodpecker is identified as a Management Indicator Species, and is representative of species dependent upon late and old structure forest/old growth that occurs in dense, multistructured closed canopy habitat. Snag densities are generally high, with a high percentage of large snags. Forest types utilized are primarily moist grand fir plant association group which is dominated by Douglas fir and grand fir species (Thomas 1979). Ponderosa pine may also be a component of this habitat. Pileated woodpeckers are also found on the Forest in drier plant association groups (dry grand fir, Douglas fir and moist ponderosa pine), but productivity of the birds is lower in these more marginal habitats. Canopy closures are high, often at 60-70% or higher (Thomas 1979). Snag and log densities are generally high, and provide nesting and foraging habitat for the pileated woodpecker. Bull and Holthausen found snag densities exceeding 4 snags per acre, of which more than 20% were greater than 20 dbh (1993). Large logs, providing carpenter ant forage opportunities were also common and abundant (Bull and Holthausen 1993). Home range size for breeding pairs is also very large. Bull and Holthausen recommended considering 900 acres of high quality suitable habitat in managing for pileated woodpeckers (1993). Of that, 75% be in grand fir forest types; 25% in old growth, remainder in mature forest; and at least 50% of that management area > or = 60% canopy closure (Bull and Holthausen 1993). The DecAID dead wood advisor (Mellen et al. 2006) identifies snag diameters and densities that are selected for by pileated woodpecker. Selection is described by tolerance levels for this species. Tolerance levels are defined by the DecAID advisor as follows: Tolerance level (limit) - the specific value at the edge of a tolerance interval. For example, if a 30% tolerance level of snag dbh used by wildlife species in a specific vegetation condition is, say, 40 cm, this means that 30% of all individuals of the wildlife populations used less than or equal to that size snag. An 80% tolerance level would correspond to 80% of the individuals using that corresponding size snag. A 100% tolerance level means all of the individuals would use that size snag (100% tolerance intervals correspond to the maximum observed values, such as the largest dbh snag observed to be used by a wildlife species). (Mellen et al. 2006). Tolerance levels as expressed in the DecAID advisor essentially establish upper level snag diameter and density levels for certain portions of the population of any one species. Using the DecAID advisor, the Eastside Mixed Conifer Forest East Cascades/Blue Mountains and Ponderosa Pine/Douglas-fir habitat types were queried. Both large tree and small/medium tree habitat conditions were also queried. For the pileated woodpecker, the following snag diameter classes and snag densities by tolerance level were given (Table B) 2

3 Table B. s and Densities for the pileated woodpecker at the 30%, 50%, and 80% tolerance levels. Species Pileated (Eastside Mixed Conifer Forest East Cascades/Blue Mountains) Pileated (Ponderosa Pine/Douglas- Fir) 25.2 dbh 29.5 dbh 36.0 dbh 14.9 snags/acre 30.1 snags/acre 49.3 snags/acre 3.5 snags/acre 7.8 snags/acre 18.4 snags/acre 25.5 dbh 30.1 dbh 36.8 dbh 14.9 snags/acre 30.1 snags/acre 49.3 snags/acre 3.5 snags/acre 7.8 snags/acre 18.4 snags/acre As noted, the pileated woodpecker selects for habitats that provide high densities of snags at different diameters, and selects for large snags for nesting purposes. Such conditions are generally found in late and old structure (LOS) moist grand fir plant association group habitats. Other Primary Cavity Excavators White-headed, Williamson s Sapsucker and Lewis All three species select for and prefer LOS ponderosa pine habitats, often with open canopies and understories and the presence of large snags used for nesting (Marshall et al. 2003). Early seral Douglas-fir and dry grand fir habitats, which are dominated by large ponderosa pine, will also provide habitat for these species. Williamson s sapsucker may prefer denser forest habitats with a higher level of understory development in ponderosa pine, Douglas-fir and grand fir, as these smaller diameter trees provide primary foraging opportunities. Sapsuckers will routinely excavate small holes into the live cambium, which causes sap to weep out of the small holes (Marshall et al. 2003). These sap wells, in turn attract insects on which the Williamson s sapsucker will feed (Marshall et al. 2003). The white headed woodpecker and Lewis woodpecker feed more on arial insects associated with open canopy ponderosa pine or gleaning insects from the boles of trees (Marshall et al. 2003). The white-headed woodpecker also focuses on pine seeds from the large pine cones produced by mature ponderosa pine trees as a primary forage source. All three species, to some degree, will utilize bark beetles and wood boring insects (Marshall et al. 2003). 3

4 Using the DecAID advisor, the Ponderosa Pine/Douglas-fir habitat type was queried. Both large tree and small/medium tree habitat conditions were also queried. For the white-headed woodpecker and the Williamson s sapsucker, the following snag diameter classes and snag densities by tolerance level were given (Table A). Table A. s and Densities for White-headed woodpeckers and Williamson s Sapsuckers at the 30%, 50%, and 80% tolerance levels. Species White-Headed Williamson s Sapsucker 20.8 dbh 26.7 dbh 35.9 dbh.3 snags/acre 1.7 snags/acre 3.7 snags/acre.5 snags/acre 1.8 snags/acre 3.8 snags/acre 20 dbh 25.8 dbh 34.5 dbh 14.0 snags/acre 28.4 snags/acre 49.7 snags/acre 3.3 snags/acre 8.6 snags/acre 16.6 snags/acre As noted in Table A, both species select strongly for large snags, with an average snag diameter of around 35 dbh at the 80% tolerance level. At the 30% tolerance level, snag diameters are still at 20 dbh. However, the species differ somewhat on snag densities, with the Williamson s sapsucker showing a preference for higher snag densities, both in the smaller snags and larger snags. Small snags in particular seem to be an important habitat component for Williamson s sapsuckers, but are not as much for the white-headed woodpecker. Black-backed s The black-backed woodpecker primarily inhabits moist and dry grand fir plant communities, according to the Wildhab analysis tool. They generally select for mature or LOS habitats that are abundant in snags. Marshall et al. also identified mixed conifer and ponderosa pine habitats as suitable for this species as well in the Blue Mountains (2003). Perhaps the biggest indicator or habitat feature that determines presence is the abundance of insect killed snags. This species keys in on insect outbreaks that are characteristic of fire events and larger beetle epidemics (Marshall et al. 2003). The larvae of woodboring beetles are the primary food source, and are most abundant in high snag density areas (Marshall et al. 2003). Using the DecAID advisor, the Eastside Mixed Conifer Forest East Cascades/Blue Mountains and Ponderosa Pine/Douglas-fir habitat types were queried. Both large tree and small/medium tree habitat conditions were also queried. For the black-backed woodpecker, the following snag diameter classes and snag densities by tolerance level were given (Table C) Table C. s and Densities for black-backed woodpecker at the 30%, 50%, and 80% tolerance levels. 4

5 Species Black-backed (Eastside Mixed Conifer Forest East Cascades/Blue Mountains) Black-backed (Ponderosa Pine/Douglas- Fir) 8.8 dbh 12.0 dbh 16.7 dbh 2.5 snags/acre 13.6 snags/acre 29.2 snags/acre 0.0 snags/acre 1.4 snags/acre 5.7 snags/acre 8.1 dbh 13.2 dbh 20.5 dbh 2.5 snags/acre 13.6 snags/acre 29.2 snags/acre 0.0 snags/acre 1.4 snags/acre 5.7 snags/acre As noted in Table C., snag diameter preferences are generally smaller, particularly when compared to other woodpecker and sapsucker species (Tables A and B). Densities of large snags are also generally much lower than the other species described above. However, the diameters of smaller snags (greater than 10 dbh) are more abundant. This is reflective of primary foraging habitat, being smaller snags attacked by bark and wood boring beetles. Hairy s Hairy woodpeckers are a bit of a habitat generalist, occupying different habitat conditions in mixed conifer and ponderosa pine habitats (Marshall et al. 2003). Varying snag densities vary, with no information on specific densities noted. Snag diameters vary, but tend to be smaller than compared to the white-headed woodpecker and the Williamson s sapsucker, which may share similar habitats. Bark beetles are often the most common forage resource, but may also include ants and other insects. Using the DecAID advisor, the Ponderosa Pine/Douglas-fir habitat type was queried. Both large tree and small/medium tree habitat conditions were also queried. In the DecAID advisor, only information was available for the hairy woodpecker. At the 30%, 50%, and 80% tolerance levels, the following snag diameters were given: 10.3 dbh; 16.4 dbh; 25.3 dbh. Snag diameter preferences are generally smaller than those of the white-headed woodpecker and Williamson s sapsucker, and more similar to the black-backed woodpecker, which shares a similar foraging strategy. Northern Flicker The northern flicker is a habitat generalist in the Project Area. Marshall et al. notes that it can be found in nearly every habitat type in Oregon, although is most common in open forest or areas close to openings (2003). On the Ochoco National Forest, the northern flicker is unique among the primary cavity excavators in that it also excavates nest wholes in western juniper trees, thereby providing unique cavity habitat for species dependent upon juniper woodland and shrub habitat (such as the western bluebird). Across conifer forest habitats, meeting or providing for habitat requirements of other cavity excavators provides for this species. 5