Spruce Grouse Habitat Model
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Spruce grouse, Dendragapus canadensis
Use of Study Area Resources:
Resident year-round throughout its range (Soule et. al 1992). Ranges "...from northern Alaska to northern Quebec, Labrador, New Brunswick, and Nova Scotia south to south-coastal and southeastern Alaska, northern Oregon, southeastern Idaho, northwestern Wyoming, western Montana, and southeastern Alberta to northern Minnesota east to northern Vermont, northern New Hampshire, and eastern Maine (range is generally congruent with that of the northern coniferous forest)" (Northern Prairie Wildlife Research Center).
Habitat Requirements (Reproduction):
Cover: "Its habitat includes a variety of forest types from boreal forest and wet spruce forests in the far north to dry jack pine and lodgepole pine forests in portions of its southern range. This great variety of habitats have in common two main features--they always include a short-needled tree component and trees with live branches to ground level, at least in patches of the area, if not throughout" (Soule et. al 1992). "In New England, spruce grouse reside in spruce-fir forests on mountain ridges and peaks, and in low elevation bogs" (Smith 1994). Robinson (1980 in Soule et. al 1992) concluded that in the northeast spruce grouse prefers wet lowland forests, but also use adjacent uplands occasionally. Hedberg and May (1981) found that spruce grouse used "lowland softwoods" more frequently and upland softwoods less frequently than would be expected, in a study in eastern Maine at low elevations.
"Small patch cuts that create interspersion of mature, dense, and open habitats while encouraging tamarack regeneration and ericaceous shrub growth may improve spruce grouse habitat suitability within large, monotypic coniferous patches of uniform age" (Bouta 1991).
"A study in Maine showed that the grouse used more open forest areas in summer than winter, probably because of greater availability of summer foods in more open areas (Hedberg 1980, Allan 1985). Similar patterns were found in New York (Chambers, pers. comm.). During the summer molting period, males in the Maine study area used areas where the forest canopy was more closed compared to the areas used by females (Hedberg 1980)" (from Soule et. al 1992).
Foraging: "During winter, consumes diet of nearly 100 percent conifer needles. In other seasons, consumes a variety of foods, including leaves, flowers, berries, seeds, pine needles, and a few insects. Needs a source of fine, mineral-rich gravel" (Northern Prairie Wildlife Research Center). One regular component of habitat everywhere is inclusion of areas with an understory of low berries, especially VACCINIUM spp., an important food source (Soule et. al 1992).
Area Requirements: "Males and females maintain territories during breeding through brood rearing (Keppie 1987 in Soule et. al 1992) In a habitat assessment for Vermont, Keppie and Beaudette (Appendix II in Pence et al. 1990) concluded that a female grouse needs 5 to 15 ha of habitat (depending on quality) to raise a brood... In Alaska, Ellison (1973) found that home range sizes were highly variable among individuals, ranging from 6 to 21 ha for preincubating females, 6 to 155 ha for brood-rearing females, 3 to 20 ha for molting males, 6 to 160 ha for either sex in fall, and 3 to 113 ha in winter. Robinson (1980) also reported highly variable range size for females with broods, but concluded that 12 to 16 ha would be adequate on the Yellow Dog Plains of Upper Michigan. Home range for broods on Mt. Desert Island, Maine, was 13-26 ha (O'Connell et al. 1995)" (from Soule et. al 1992). Whitcomb et al. (1996) found the minimum occupied patch of black spruce/tamarack on Mt. Desert Island was 8 ha.
The Breeding Bird Atlas (BBA) data for Maine, New Hampshire and Massachusetts (courtesy of the University of Vermont COOP Unit) were used to identify the range of the spruce grouse within the study area. BBA blocks in which spruce grouse were known to occur were used to select USDA Forest Service Ecological subunits (Keys et al. 1995); habitat mapping then was restricted to these areas.
The model regarded spruce grouse habitat in this locality as being of two types. These were: 1) any coniferous vegetation at higher elevations ("ridges and peaks" of Smith 1994), and 2) coniferous swamps at lower elevations. We noted that all New Hampshire BBA blocks occupied by spruce grouse had some coniferous vegetation at 500 m or higher elevation, and so this was used as the threshold elevation for the first type. In lowland areas, wetland coniferous shrub and forest were selected as habitat (see table, below).
|Cover Types||Cover Suitability
(0 - 1 scale)
|Upland deciduous forest|
|Upland coniferous forest||1.0*|
|Upland mixed forest|
|PEM, L2EM||Lake/pond, emergent vegetation|
|PFOcon||Palustrine forest, conifer||1.0|
|PFOdec||Palustrine forest, deciduous|
|PSSdec||Palustrine scrub shrub, deciduous|
|PSScon||Palustrine scrub shrub, conifer||1.0|
|PAB, L2AB||Lake/pond, aquatic vegetation|
|L1UB, PUB||Lake/pond, unconsolidated bottom|
|L2US||Lake, unconsolidated shore|
|L2RS||Lake, rocky shore|
|R1UB||Riverine subtidal unconsolidated|
|E1AB||Estuarine subtidal vegetated|
|E1UB||Estuarine subtidal unconsolidated bottom|
|E2AB||Estuarine intertidal algae|
|E2EM||Estuarine intertidal emergent|
|E2RS, R1RS||Estuarine, tidal river rocky shore|
|E2SS||Estuarine intertidal shrub|
|E2US||Estuarine intertidal unconsolidated shore|
|M1AB||Marine subtidal vegetated|
|M1UB||Marine subtidal unconsolidated bottom|
|M2AB||Marine intertidal algae|
|M2RS||Marine intertidal rocky shore|
|M2US||Marine intertidal unconsolidated shore|
|NOTES||*if at elevation > 500 m|
Area suitability: Patches of suitable cover of 8 ha or larger extent were regarded as the minimum necessary; smaller patches were deleted from the final coverage.
Model testing: We lacked relatively fine resolution occurrence data with which to test the habitat map. The Breeding Bird Atlas data had already been used for inspecting or selecting parameters of the model, and so was not appropriate for testing the distribution of mapped habitats. However, we verified that all BBA blocks having 'probable' or 'certain' occurrences also had mapped habitat. We obtained the vegetation map referred to by Whitcomb et.al. (1996) and used this to locate 8 black spruce-tamarack patches at which they observed spruce grouse. The model identified 4 of these as habitat; 2 were not identified as habitat because NWI mapped them as upland, and 2 were mapped as smaller patches than the 8 ha minimum. Of 10 black spruce-tamarack sites at which grouse were not observed by Whitcomb et.al., only 2 were mapped as habitat with the above model.
Bouta, R.P. 1991. Population status, historical decline and habitat relationships of spruce grouse in the Adirondacks of New York. M.S. Thesis, SUNY ESF, Syracuse, 117 pp.
Hedberg, J. and T.A. May. 1981. The distribution and habitat selection of spruce grouse in Maine. Update; Projects and Progress in Life Sciences and Agricultural Research, Univ. of Maine at Orono. Vol. 9(3).
Keys, J.E., Jr., J.C. Carpenter, S. Hooks, F. Koenig, W.H. McNab, W. Russell and W. Smith. 1995. Ecological units of the eastern United States - first approximation (map and booklet of map unit tables), USDA Forest Service. Atlanta, GA.
Northern Prairie Wildlife Research Center. Forest and Rangeland Birds of the United States, Natural History and Habitat Use: Spruce Grouse -- Dendragapus canadensis. http://www.npwrc.usgs.gov/resource/1998/forest/species/dendcana.htm; downloaded 10/19/01
Smith, S. 1994. Spruce grouse. In C.R. Foss (ed.) Atlas of Breeding Birds in New Hampshire. Audubon Soc. of New Hampshire, Concord, NH. 414 pp.
Soule, J., G. Hammerson and D.W. Mehlman. 1992. Species Management Abstract: Spruce grouse (Falcipennis canadensis). THE NATURE CONSERVANCY, 4245 North Fairfax Drive, Suite 100, Arlington, VA 2220. Edition Date: 1992-05-21. Downloaded at: http://www.natureserve.org/
Whitcomb, S.D., F.A. Servello, and A.F. O'Connell, Jr. 1996. Patch occupancy and dispersal of spruce grouse on the edge of its range in Maine. Can. J. Zool. 74: 1951-1955.