Wildlife Interpretations - Black-tailed Deer

Transcription

1 3.0 SPECIES-HABITAT MODEL FOR BLACK-TAILED DEER Common Name: Black-tailed Deer Scientific Name: Odocoileus hemionus columbianus Species Code: M-ODHC B.C. Status: Yellow-listed Identified Wildlife Status: None COSEWIC Status: Not applicable 3.1 Introduction Columbian black-tailed deer are a subspecies of interior mule deer and have been studied extensively in the province, producing information on many aspects of blacktailed deer life requirements. Local information from the study area was utilized as much as possible in developing this account and was supplemented with additional data where required and/or applicable. 3.2 Distribution Provincial Range and Context The black-tailed deer, Odocoileus hemionus columbianus, is one of three subspecies of mule deer recognized in British Columbia. While the mule deer is common throughout most of the province (except in the northwestern and north central regions), the coastal subspecies occurs on most islands south of Rivers Inlet, Vancouver Island, and east to near the summits of the Cascade and Coast ranges (RIC, 1998). Mule deer densities are highest along the coast, including the Queen Charlotte Islands and Vancouver Island. Populations in B.C. are stable, and currently approximately 180,000 Columbian Black-tailed deer reside in B.C. (Ian Hatter, pers. comm.). Columbian Black-tailed deer occur from sea level to subalpine habitat, although elevations greater than 1000 m are rarely used as winter habitat (RIC, 1998) Project Area Ecoprovince: Coast and Mountains Ecoregions: Western Vancouver Island Ecosections: Northern Island Mountains (NIM) (N & Z) and Windward Island Mountains (WIM) (Q) Biogeoclimatic Zones: CWHvm1, vm2, and xm2, MHmm1 and mmp1, AT Distribution in : The sub-species of black-tailed deer, Odocoileus hemionus columbianus, is fairly common and ranges throughout the project area. Deer are found in all of the BEC variants present within the Sound Year Two study areas. On a provincial basis, black-tailed deer have a moderate (1 deer per km 2 ) to plentiful (over 1 deer per 0.2 km 2 ) relative abundance within the Gold River study area (Fish, Wildlife and Habitat Protection Department, 1994). Elevational Range in : Within the three study area compartments, black-tailed deer occur at all elevations during the growing season, ranging from sea level to the alpine tundra (AT) biogeoclimatic zone occurring above 1,250 m. Compartments N (Upper ) and Z (Gold Lake) contain elevations ranging from 180 m to 1560 m, and 300 m to 1440 m respectively. Compartment Q (also referred to as Norgate or Conuma River Drainage - coastal) ranges in elevation from 0 m to 1,250 m in the AT. During the winter, deer are restricted to lower elevations due to snowpack. 3.3 Ecology and Habitat Requirements Black-tailed deer require food, water, and cover to ensure survival during the spring, summer, and winter seasons. During spring, deer favour areas with early green up (e.g., low elevation areas with warm aspect on moderate to steep slopes). Summer habitat consists of areas with a suitable mix of young to old forest Madrone Consultants Ltd. 1

2 areas with an adequate supply of forage and cover elements. Winter forces deer from high elevation habitat to low elevation areas with south-facing, warm-aspect slopes, or floodplain areas where snowpack is very low. Although deer are capable of digesting a wide variety of plants, forage preferences are determined, in part, by seasonal variations in forage digestibility and protein content, and by the nutritional requirement of the animals (Nyberg & Janz, 1990). Optimum growth occurs in the spring when plant proteins are easily digestible, whereas fall and winter represent periods of maintenance. Black-tailed deer breed during November and early December. Fawns are born during the first half of June. It remains unclear whether specific habitats are used for Columbian black-tailed deer reproduction habitat. Reproduction habitat will not be rated separately. Black-tailed deer populations can have either resident or migratory individuals. Average annual home range for migratory deer in the moderate snowpack zone is 1770 ha, whereas the home range for resident deer in the same zone is 140 ha (Nyberg & Janz, 1990). In deep snowpack average annual home ranges decrease from 48 ha in the winter to 25 ha in the spring. They generally migrate between seasonal habitats within a watershed, typically moving from good, higher elevation, summer habitats to winter habitats consisting of low elevation, south facing, warm aspect slopes or floodplain areas where snowpacks are very low (Nyberg and Janz, 1990). Where a suitable habitat mix of young to old forest areas occur, black-tailed deer may also be non-migratory, remaining in very small home ranges (McNay and Davies, 1985). 3.4 Habitat Use (Life Requisites and Seasons) Black-tailed deer habitat use for the study area is broken down into two seasons: Growing (April - October) and Winter (November March). Life requisites that are rated for the Columbian black-tailed deer include feeding, security, and thermal cover, as summarized in Table 6. Madrone Consultants Ltd. 2

3 Table 6: Summary of Life Requisites and Seasons of Use for Black-tailed deer in the Study Area (Compartments N, Q, and Z). Season Code Habitat Use Months* Comments Growing G Feeding and Security/ Thermal Habitat (FD/ST) Early Spring April - October Growing season encompasses spring, summer and fall requirements as listed below. P FD/ST April Activity concentrated on feeding on emergent, easily digestible spring vegetation. Spring P FD/ST May - June Low elevation areas with warm aspect on moderate to steep slopes. Summer S FD/ST June-August Birthing: first half of June (Nyberg and Janz, 1990). Fall F FD/ST September-October Winter W FD/ST November-March Rut: mid-november to early December (Nyberg and Janz, 1990). *Seasons defined per the Chart of Seasons by Ecoprovince (RIC, 1998; Appendix B). **Seasons in bold indicate rated for this project Feeding Habitat Growing Season Black-tailed deer have a diverse diet including a variety of grasses, forbs, shrubs, trees, sedges, agricultural crops, mushrooms, and lichens, depending on season (Petticrew and Jackson, 1980). In spring, important forage species include fireweed, pearly everlasting, bunchberry, Rubus spp, Vaccinium, willow species, and many herbs and grasses (Nyberg and Janz, 1990). Key summer species utilized are fireweed, pearly everlasting, salal, and Rubus and Vaccinium species, willow and alder (Nyberg and Janz, 1990). Table 7 summarizes the important forage species for black-tailed deer. Adjacency of early spring range to winter range is critical. Steep south-facing slopes are often the first areas to green up in early spring (Luttmerding et al., 1990). Herbaceous open areas and floodplain forests may also be important spring areas. Early and intermediate seral stages after burning or logging often provide abundant foods and are good spring and summer habitats, providing sufficient security cover is available. Deer may migrate to higher elevations in late summer and fall to take advantage of newer growth resulting from delayed phenology (Nyberg and Janz, 1990). Open forests and natural openings also provide high quality forage throughout the growing season. Table 7: Important Forage Plants for Black-tailed Deer in Southern British Columbia. (Taken from Nyberg and Janz (1990). The most important or preferred species are printed in bold type.) Winter forage Spring forage Summer forage TREES: Douglas-fir bigleaf maple red alder Madrone Consultants Ltd. 3

4 western hemlock western redcedar Douglas-fir SHRUBS: Alaskan blueberry Rubus spp. salal five-leaved bramble (salmonberry, blackberry, willow spp. kinnikinnick thimbleberry, raspberry, oval-leaved blueberry bramble) red huckleberry salal rose spp. willow spp. salal saskatoon twinflower vine maple willow spp. FERNS: deer fern bracken HERBS: bunchberry bunchberry fireweed grass spp. fireweed grass spp. grass spp. hairy cat s-ear hairy cat s-ear pearly everlasting horsetail pearly everlasting ARBOREAL LICHENS: Alectoria Bryoria Lobaria oregana Usnea spp Security Habitat Growing Season Interspersion of food and cover is very important in determining deer habitat quality. Optimal habitat consists of open areas closely interspersed with forests so deer can conceal themselves from predators. Minimum security cover for deer has been defined as vegetation capable of concealing 90% of a deer from view at a distance of 60 m or less (Thomas et al., 1979). The stand s density and diameter of trees and the density of understorey vegetation determine its value as security cover (Nyberg and Janz, 1990). Tree boles and foliage provides the best cover, yet short, dense vegetation and CWD can provide adequate screening for deer in some areas (Nyberg and Janz, 1990). In flat terrain, small trees, 1 m to 2 m in height, can provide effective cover (Armleder and Dawson, 1992). In more uneven terrain, topographic features such as swales or dips can often provide sufficient hiding cover for deer (Nyberg and Janz, 1990). Bluffs or ridges that offer an unimpeded view of the surrounding terrain may also have value as security habitat (Nyberg and Janz, 1990). Security cover reduces deer energy expenditure by reducing the need and the distance to flee (Armleder and Dawson, 1992; Armleder et al., 1986). Deer will typically remain within 200 m of security cover; the centres of openings more than 400 m wide would receive very little use unless topographic features provided some security cover (Nyberg and Janz, 1990) Thermal Habitat Growing Season (From RIC, 1998) Thermal habitat can vary daily, seasonally, with prevailing weather conditions, and age, size, and nutritional condition of the animal. In general, nighttime thermal cover should trap long-wave radiation and maintain warmer air temperatures (occurring under a closed canopy above a deer s head or above 3 m), reduce wind at deer height (occurring in a forest stand or dense underbrush), and intercept precipitation (occurring under a closed canopy and large crown volume). In general, daytime thermal requirements are Madrone Consultants Ltd. 4

5 met by areas that gather heat (on or near rock bluffs, in clearcuts) or intercept excessive solar radiation (canopy closure) Feeding Habitat - Winter Winter forces deer from high elevation habitat to low elevation areas with south-facing, warm-aspect slopes or floodplain areas where snowpack is very low (i.e., CWHxm; RIC, 1998). Key winter forage species within the coastal region include western redcedar, Douglas-fir, red huckleberry, salal, deer fern, and arboreal lichens (Nyberg and Janz, 1990). In severe winters when snow depth precludes use of other forage species, arboreal lichens (especially Alectoria, Bryoria, and Usnea species), western redcedar, and Douglas-fir compose the main diet Thermal-Security Habitat - Winter Conditions that produce favourable snow conditions for Columbian Black-tailed deer include dense younggrowth (>10 m tall) and old-growth forests (Nyberg & Janz 1990). Canopy closure (i.e., stands, taller than 10 m with greater than 60% crown closure) exerts the most influence on snow interception, and creates areas with snow conditions that don t limit deer movement (Bunnell et al in RIC, 1998). Thermal cover is emphasized in the ratings as security cover is much less limiting Seasons of Use Food and security are required throughout the year for the black-tailed deer in the Northern Island Mountains (NIM) and Windward Island Mountains (WIM) ecosections. In the early spring, black-tailed deer concentrate their activity to feeding on emergent, easily digestible, spring vegetation. In the growing season, black-tailed deer require feeding and security habitat. In the winter season, black-tailed deer have specific thermal and feeding requirements. Table 8 summarizes the rated life requisites for the Columbian black-tailed deer for each month of the year. Madrone Consultants Ltd. 5

6 Table 8: Monthly Rated Life Requisites for Black-tailed deer in the Gold River Study Area (Compartments N, Q and Z). Month Season Rated Life Requisites (as per RIC 1998) January Winter Feeding, Thermal/Security February Winter Feeding, Thermal/Security March Winter Feeding, Thermal/Security April Early Spring Feeding May Growing (late spring) Feeding, Security/Thermal June Growing (summer) Feeding, Security/Thermal July Growing (summer) Feeding, Security/Thermal August Growing (summer) Feeding, Security/Thermal September Growing (fall) Feeding, Security/Thermal October Growing (fall) Feeding, Security/Thermal November Winter Feeding, Thermal/Security December Winter Feeding, Thermal/Security *Seasons defined for the Coast and Mountains Ecoprovince as per the Chart of Seasons by Ecoprovince (RIC, 1998; Appendix B). 3.5 Habitat Use and Ecosystem Attributes Table 9 outlines how each rated life requisite relates to specific terrestrial ecosystem mapping (TEM) attributes (e.g., site series/ecosystem unit, plant species, canopy closure, age structure, slope, aspect, terrain characteristics). Further details are provided in the assumption section on how the ecosystem attributes relate to habitat ratings. Table 9: Life Requisite Terrestrial Ecosystem Mapping (TEM) Relationships for each Life Requisite for Columbian Black-tailed deer. TEM Attributes Feeding Habitat Site: site disturbance, elevation, slope aspect, structural stage Vegetation: % cover by layer, species list by layer, cover for each species for each layer Security Habitat Site: elevation, slope, aspect, structural stage Soil/terrain: terrain texture Vegetation: % cover by layer Thermal Habitat Site: elevation, slope, aspect, structural stage Soil/terrain: terrain texture Vegetation: % cover by layer 3.6 Development of Habitat Ratings Rating Scheme A 6-class rating scheme of high (1), moderately high (2), moderate (3), low (4), very low (5), and nil (6) is employed due to the detailed level of knowledge on habitat use of black-tailed deer (RIC, 1998). The used ratings scheme is defined in Table 4. Units are rated for general habitat values for living for two seasons: the Growing season (G) and Winter (W), as defined in the Seasons of Use section Provincial Benchmark The provincial standard (best in B.C.) for the Columbian/coastal black-tailed deer is the Leeward Island Mountains (LIM) ecosection (RIC, 1998). Most of the study area is located within the NIM and WIM ecosections, which have a high value % and Moderate 50-26% capability respectively, compared to the standard (RIC, 1998). Madrone Consultants Ltd. 6

7 Overall, the study area is expected to have a moderate to high capability for the black-tailed deer. Table 10 lists the provincial benchmark habitat for this species (shaded rows). Habitat units located within the study area that have been rated to par with the best habitat (a rating of 1) have also been included. This additional information is based on field assessments by Madrone Consultants Ltd. (Clayoquot Sound Year 3 Wildlife Report Addenda, 1999), as well as information from the Ministry of Environment s provincial database of best habitat ratings. Table 10: Provincial benchmark and high value study area habitat for Coastal Black-tailed Deer. Ecoprovince Ecosection BGC Broad Ecosystem Unit/Seral Stage Rating Coastal Black-tailed Deer Winter Unit Rating Subzone Coast and Mountains NIM 1 CWHxm CD/6 Coastal Douglas-fir 1 WIM 1 CWHvm1 AB/6 & 7 Western hemlock-amabilis fi - 1 Blueberry WIM 1 CWHvm1 RS/6 & 7 Western redcedar-western hemlock-sword fern Georgia Depression LIM B CWHvm CW/6 - Coastal Western hemlock-douglas-fir 1 Growing Season Coast and Mountains NIM 1 CWHxm CW/1 Coastal Western hemlock-douglas-fir 1 WIM/ 1 CWHvh1, CG/3 Cultivated Garden 1 NIM vm1, vm2 WIM/ 1 CWHvm1, SS/3, 6 & 7 Sitka spruce-salmonberry 1 NIM vm2 WIM/ 1 CWHvm1, IF/2 Indian hellebore-fern 1 NIM vm2 & MHmm1 Georgia Depression LIM B CWHxm DA/1 Douglas-fir-Arbutus 1 *Note The Study areas do not contain the CWHvh subzone Ratings Assumptions A first approximation of general habitat ratings is presented in Appendix I. In developing habitat interpretations, assumptions were based on information found in published literature cited above and unpublished literature including Radcliffe and Ryan (1997), supplemented with personal knowledge and field data (see Table 11). Madrone Consultants Ltd. 7

8 Table 11: Habitat Ratings Assumptions for Black-tailed deer. Rated Life Requisite and Season Feeding Requirements in the Growing Season FD_G Security/Thermal Requirements in the Growing Season ST_G Feeding Requirements in the Winter Season FD_W Assumptions Structural Stage: Clearcuts should provide moderate to high summer forage. Structural stages 2 and 3 should provide abundant forage and have good spring and summer values for deer. Stage 3 units were rated more strongly towards feeding values than security values. Stage 4 stands generally have poor year round foraging value. Generally, food availability increases with the age of the stand. Therefore, where forest cover is established, stage 7 forests are rated as highest value, with mature stage 6 forests having slightly less value, and young stage 5 forests moderate foraging values. Vegetation Characteristics: Riparian stands should provide good habitat throughout the growing season Structural Stage: Stage 4 stands contain pole-saplings that should provide good security and thermal cover and increase the value of more open feeding areas adjacent to them. Structural stages 5 to 7 should generally provide adequate thermal and security cover for black-tailed deer during spring through fall. Structural Stage: Structural stages 1 to 4 have minimal winter values. In the low elevation subzones, they may be available to deer, but during more severe winters, snow may preclude access to these stands. Stage 4 forests generally have poor year round foraging value as these stands are typically dense and forage has been shaded out. Stage 5 forests generally have little forage available to function as good winter range, but where adjacent to better feeding units, they may be sufficient to function as winter range in the warmer subzones in most years. In severe winters however, these stands will not provide adequate winter range. Mature stands (stage 6) tend to provide more forage in severe winters as shrub layers are well developed and, particularly, as arboreal lichens also tend to be more abundant. Old-growth forests (stage 7) provide the best food availability in winter, so are rated relatively high for food. Site: The MHmm subzone generally will have deep snowpacks in the winter, and units are therefore usually inaccessible to deer in winter and early spring. They may have some value in mild winters, yet are generally rated as nil value in winter and nil or very low value in spring. Madrone Consultants Ltd. 8

9 Table 11 (Cont d): Rated Life Requisite and Season Security/Thermal Requirements in the Winter Season ST_W Habitat Ratings Assumptions for Black-tailed deer. Assumptions Structural Stage: Stage 4 forests may provide limited thermal and security cover, depending on adjacent habitat. Young forests of structural stage 5 often have some good values for thermal cover, depending on forage availability, subzone and snowpack. Stage 6 provides good thermal cover and snow interception, and this combination of good canopy closure and reasonable food availability may provide some of the best winter range conditions in the area. Because of the uneven canopy with many gaps in stands of stage 7, thermal cover is often not as good as in a mature stand. There is a great deal of variability, however, and patchy, uneven aged stands on steep slopes can provide some of the best winter ranges for deer during severe conditions. Vegetation Characteristics: Mountain Hemlock (MH) zone is poor deer habitat in winter and early spring because of excessive snowpack. Site: Warm aspect slopes are best. The MHmm subzone generally will have deep snowpacks in the winter, and units are therefore usually inaccessible to deer in winter and early spring. They may have some value in mild winters, and are generally rated as very low in winter and spring. The CWHvm1 is better than the vm2 due to lower snowpacks Ratings Table Preliminary habitat ratings are presented in Appendix I Rating Adjustment Considerations Adjustments (e.g. warm versus cool aspect slopes) typically increase or decrease the suitability value of a site by a single class. This has already been incorporated into the ratings. However, further refinement of aspect is possible. Habitat ratings refinement/adjustment requires field verification. Madrone Consultants Ltd. 9

10 3.7 References Armleder, H. M. and R. J. Dawson Logging on Mule Deer Winter Range: An Integrated Management Approach. Forestry Chronicle 68: Armleder, H. M., R. J. Dawson and R. N. Thomson Handbook for Timber and Mule Deer Management Co-ordination on Winter Ranges in the Cariboo Forest Region. Land Management Handbook No. 13. B.C. Ministry of Forests, Victoria, B.C. Bunnell, F.L., R.S. McNay, and C.C. Shank Trees and snow: the deposition of snow on the ground. A review and quantitative synthesis. B.C. Min. Environ. and Min. For., Victoria, B.C. IWIFR-17. Fish, Wildlife and Habitat Protection Department Wildlife Distribution Mapping, Big Game Series. 16 maps, 1:2,000,000.Ministry of Environment, Lands and Parks, Victoria, B.C. Harestad, A. S., J. A. Rochelle, and F. L. Bunnell Old-Growth Forests and Black-Tailed Deer on Vancouver Island. Trans. N. Am. Wildl. Nat. Resour. Conf. 47: Hatter, I. Pers. comm Ungulate biologist, Ministry of Environment, Lands and Parks, Wildlife Branch, Victoria, B.C. Luttmerding, H. A., D.A. Demarchi, E. C. Lea, D. V. Meidinger, and T. Vold. (Eds.) Describing Ecosystems in the Field, 2nd Ed. MOE Manual 11. B.C. Ministry of Environment and B.C. Ministry of Forests, Victoria, B.C. Madrone Consultants Ltd Interim Report Clayoquot Sound Year 3 Wildlife Report Addenda. Madrone Consultants, for Ministry of Forests, Port Alberni, Vancouver Island. McNay, R. D., and R. Davies Interactions Between Black-Tailed Deer and Intensive Forest Management: A Problem Analysis. For. Res. IWIFR-22. B.C. Ministry of Environment, Victoria, B.C. McNay, R.S. and Doyle, D.D Winter habitat selection by black-tailed deer on Vancouver Island: A job completion report. BC Min. Environ. And Min. For., Victoria, B.C. IWIFR-34 Nyberg, J. B. and D. W. Janz, technical eds Deer and Elk Habitats in Coastal Forests of Southern British Columbia. Ministry of Forests, Special Report Series 5, Research Branch, Victoria, B.C. Petticrew, P. S., and L. Jackson Preliminary Deer Management Plan for British Columbia. B.C. Min. Environment, Fish and Wildlife Branch., Victoria, B.C. Thomas, J. W., H. Black, R. J. Scherzinger, and R. J. Pedersen Deer and Elk. In Wildlife Habitats in Managed Forests: the Blue Mountains of Oregon and Washington. J. W. Thomas (tech. editor). U. S. Dept. Agric. For. Ser., Agric. Handb pp Radcliffe, G. and M. Ryan Ecosystem Mapping and Wildlife Interpretations for the Chapman-Gray Study Area, Sechelt. Report for International Forest Products Ltd., Sechelt, B.C. Resources Inventory Committee Standards for Wildlife Habitat Capability/Suitability Ratings in British Columbia. Wildlife Branch, Ministry of Environment Lands and Parks, Victoria, B.C. Madrone Consultants Ltd. 10