Values of Four Communities for on Ranges with Limited Summer Habitat

DENNIS D. AUSTIN AND PHILIP J. URNESS

Abstract Four communities were evaluated from May through summering range for deer on areas lacking typical high mountain September for mule deer dietary and nutritional values. The com- habitats. This paper presents data from 4 important plant com- munities were dominated by serviceberry, Gambel oak, big munities found in areas of limited summer range and assesses their sagebrush, and mixed browse. In early summer deer diets con- value for mule deer during that season. tained many browse and forb species and were high in crude Study Area protein, but as summer progressed fewer species were selected and dietary crude protein declined, especially in the big sagebrush and The region of concern lies within the geographic serviceberry communities. Thus late summer was determined the unit (Durrant 1952, Armstrong 1977) of western Utah and eastern critical period for forage quality. Range conditions were reflected Nevada. This area contains many small, scattered, north-south by body size and condition of deer in fall. trending mountain ranges within the vast expanse of cold desert. Typically the mountains have an elevational gain of less than 700 m Little information is available on the value of various plant from valley floors, and lush summer range habitats are largely communities for mule deer where summer range is limiting and lacking throughout the geographic unit. The study site, located on winter range is extensive. Furthermore, criteria are lacking for the east slope of the Sheeprock Mountains, Utah, spanned an determining optimum deer densities on these summer ranges. elevation of I ,950-2,300 m and averaged 25-40 cm precipitation, Although the extent of winter range is more often the limiting received mostly as snow during winter. The site contained several factor for deer herds in the Intermountain Region, numerous herds plant communities associated with changes in elevation and aspect have restrictive summer ranges, yet contribute substantially to the which are commonly found on mountains within the geographic harvested resource. In Utah, a minimum of 9, and possibly 19, of 60 unit. Four major plant communities dominated by Utah service- total deer units are limited by summer range; they contributed berry ( utahensis), Gambel oak (Quercus gambelii), 9-22% of the total 1977-82 harvest. big sagebrush (Artemisia tridentata), and mixed browse were In this paper summer range is used as areas where deer are found selected for study. These communities, extending from the pinyon- in summer. However it should be recognized that the communities juniper woodland at lower elevations to the mountain crests, com- studied were far different from the lush mountain meadow, aspen, prised most of the mule deer summer range. However, the amount riparian, or conifer habitats commonly associated with mule deer of summer range comprised less than 17% of the total range within summer range. In contrast the communities studied are warm and this deer unit and appeared the primary habitat factor controlling dry in summer and provide summer range mostly comprised of population size. broad-leaved communities that vary in composition. They are commonly considered as winter range for deer in areas where Methods lush summer range is extensive, but they provide most of the Composition of mule deer diets was estimated monthly from Authors are wildlife biologist and associate professor, Department of Range May through September 1981 using 3 tame, adult does. Each Science, Utah State University, Logan 84322. This paper is a contribution of Utah State Division of Wildlife Resources, Federal sampling period consisted of observing a minimum of 1,000 bites Aid Project W-105-R. per deer during a minimum of 2 feeding hours in each of 4 com- Manuscript accepted May 10. 1984.

JOURNAL OF RANGE MANAGEMENT 36(2), March 1985 167 munities. Diets were determined as percent dry weight consump- examined at checking stations in October 1980-82. The ages of tion by species using 25-50 hand-harvested, simulated bites per deer were determined in the field (Robinette et al. 1957), deer were species, collected monthly (Deschamp et al. 1979). Deer were weighed (eviscerated weight), subcutaneous fat depth was mea- allowed to graze while freely roaming within each plant commun- sured (Austin 1984), and the number of antler tines were counted ity during diet sampling and were kept within a 0.4 ha on-site (Robinette et al. 1977). Similar data were collected on Utah’s enclosure between trials to assure continued forage familiarity. Current Creek unit, where summer range is extensive and typical of Common browse forages were cut and hauled to the enclosure the central Rocky Mountain Region in terms of composition and daily when their availability became limited after extended use. growth conditions. Deer were also supplemented with alfalfa hay ad libitum (Regelin Results et al. 1976). Forage availability by species for each plant community was Available forage determined by the macroplot method yielded estimated monthly immediately following diet determinations results close to those obtained through double sampling (Table 1) from 5 permanent macroplots. The macroplot locations were with coefficients of determination (rz) ranging from .90 to .99 over selected to represent the plant communities within th’e diet sam- the 4 plant communities. Generally, production of shrub species pling area. Each permanently marked macroplot was 10 X 20 m, was slightly overestimated by the microplot method while forbs and available forage was determined by encompassing the perime- and grasses were underestimated when compared to double sam- ter with a string and obtaining weight estimates for all individual pling results. species enclosed. This procedure (Austin and Urness 1983) is much Utah Serviceberry Community faster than conventional double sampling techniques and was Forage selection by mule deer in this community had very low adopted because of time constraints. However, to compare accu- diversity, with Utah serviceberry comprising the bulk of the diet racy, a double sampling procedure was also cotipleted for July throughout the summer (Table 2). Although forbs had low availa- (Poulton and Tisdale 1961, Deschamp et al. 1979). Within each bility, they comprised 36% of the diet in May but decreased rapidly macroplot, weight estimates were made on 40 microplots, 10 on in dietary contribution in later months, reflecting maturity and each of 4 randomly located belts, and every tenth, randomly senescence. Forage availability was highest in May and declined selected, plot was clipped for adjusting estimates. Ground and throughout the summer (Table 1). The diet was high in CP in May plant-canopy cover were also estimated. Plant samples were col- and June, but greatly decreased as the value of Utah serviceberry lected monthly for converting to oven-dry weight. Species compris- declined in July and August. Dietary CP dropped below 7% in ing 95% or more of the weighted monthly diets were individually September (Fig. I), but was low as early as July analyzed for crude protein (CP). To assess animal condition, hunter-harvested buck deer were

Table 1. Available forage (dry weight basis) within plant communities as determined by macroplot weight estimate: % of total production by important species, and total production (kg/ha) by communities. Microplot double sampling comparison for July indicated in ( ).

Month Plant community Species May June July Aug. Sept. % % % % % Utah serviceberry** Amelartchier utahensis 21 29 36(33) 23 20 Artemisia spp. 62 58 50(35) 51 51 Other browse I 1 2(3) 3 3 Forbs 8 4 3(l2) 5 3 cactus 2 2 2(3) 7 IO Grasses 6 6 7(14) II 13 Available forage production (kg/ ha) 1500 1130 980(770) 520 350 Gambel oak* Quercus gambelii 17 46 71(62) 71 76 Artemisia tridentata 6 3 2(2) 4 6 Other browse 3 2 l(4) 2 2 Forbs 46 24 9(1l) 2 1 Grasses 28 25 l7(21) 21 I5 Available forage production (kg/ ha) 190 500 590(710) 240 200 Big sagebrush* Artemisia tridentata 29 32 36(34) 50 39 Juniperus osteosperma II 14 13(7) 21 35 Artemisia arbuscula 3 5 5(3) 9 8 Other browse 2 7 5(7) 5 4 Forbs I9 12 5(11) I I Grasses Ii 30 36(38j I4 I3 Available forage production (kg/ ha) 1500 1490 1360(1610) 780 610 Mixed browse** Symphoricarpos oreophilus 20 26 28(35) 25 13 Ouercus aambelii 2 I3 22(13) 23 I9 >rtemisii tridentata 32 39 27(21) 32 42 Other browse 1 3 5(7) 6 9 Forbs 42 5 2(8) 1 0 Grasses 3 14 l6( 16) 13 17 Available forage production (kg/ ha) 780 840 101q1140) 580 550 *Macroplot and microplot sampling comparisons were the same (PCOS). **Macroplot and microplot sampling comparisons were the same @<. IO).

166 JOURNAL OF RANGE MANAGEMENT 36(2), March 1965 with lower abundance of other broadleaf (Table 1). Palata- ble browse and forb species were scarce in relation to nonpalatable forages and were less abundant than in the oak or serviceberry Plant Communitv communities, which each contained one highly abundant, palata- ble forage. However, the diet remained more diverse. Dietary CP - Utah Serviceberry was high during May, June and July, but dropped below 8% during August and September. _-_- Gamble Oak .-.- Big Sagebrush Mixed Browse Community se...... Mix& B-w This community occurs elevationally above the 3 previously described communities, comprises more than 30% of the available summer range on this deer unit, and is common throughout the 79 geographic unit. It is characterized by a good mixture of deciduous DIETARY shrubs, grasses, and forbs (Table 1). In early summer forbs domi- CRUDE nated the diet with mountain snowberry (Symphoricarpos oreo- PROTEIN philus) and Utah serviceberry comprising the remainder. Impor- tant forbs included common dandelion (Taraxacum officinale), longleaf phlox (Phlox longifolia), ballhead waterleaf (Hydrophyl- lum capitatum), and Astoria violet (Violapraemorsa). As summer progressed and forbs became less available, use switched to shrubs. By September use of grass growth was observed. Although CP content of forage declined from early summer, CP remained at levels above 10% (Fig. 1).

-7- Animal Condition MAY J;N J;L Ah 7 MONTH Mule deer were found to be comparatively small (Table 3) on this area in fall. Yearling bucks had a mean eviscerated weight of Fig. 1. Weighted crudeprotein content by month of mule deer dietsfrom 4 38.3 kg over 3 years (1980-82) and 49% were spikes. Two-year-old communities. bucks averaged 49.5 kg and 47% exhibited only 2-points on each antler. On the Current Creek Unit during the same period, yearling Gambel Oak Community bucks averaged a significantly different (K.05) 41.3 kg and 29% Forb availability was high (Table 1) and diets were quite diverse were spikes while 2-year-old bucks weighed 56.0 kg and 32% were in May, June, and into July. By August the availability of forbs 2-points. Austin and Urness (1976) reported mean weights for greatly declined and the diet was almost entirely oak (Table 2). Utah bucks in general was 44.5 kg and 55.5 kg for yearling and Forbs remained available, green and palatable 3 to 4 weeks longer 2-year-olds, respectively. Furthermore, buck deer on the Shee- under the oak canopy than in adjacent openings. Due to the high prock Mountains were found to have only fair subcutaneous fat CP content of oak leaves (1 l%), percent dietary protein remained depths (measured at the xiphoid process) in fall compared to units above 10% throughout the summer (Fig. 1). with good summer range (Austin 1984). The deer population was Big Sagebrush Community expanding during the study, but was considered to be below opti- This community is comprised mainly of big sagebrush and grass mum carrying capacity.

Table 2. Major forages of mule deer diets ($ dry weight f SE,,,) on four plant communities through the summer.

Month Plant Community Species May June July August September Utah serviceberry Amelanchier utahensis 61.5 f 7.0 80.2 f 5.8 88.0 f 7.2 93.8 f 1.6 96.4 f 2.9 Other browse 2.3 f 1.0 4.1 f 1.5 1.4 f 0.7 0.2 f 0.1 0.4 f 0.4 Total forbs 36.2 f 7.4 15.5 f 4.6 10.6 f 6.7 6.0 f 1.7 3.2 f 3.0 Gambel oak Amelanchier utahensis 5.2 f 4.5 1.7 f 1.7 7.2 f 5.8 2.1 f 1.0 2.2 f I.0 Quercus gambelii 15.7 f 5.8 27.8 f 8.0 60.2 f 9.1 89.8 f 7.5 96.1 f 1.7 Symphoricarps oreophilus 0.8 f 0.7 3.3 f 0.4 3.3 f 1.8 2.8 f 1.8 1.3 f 0.8 Other browse 0.7 f 0. I 1.5 f 0.6 3.8 f 0.8 3.0 f 2.9 0.3 f 0.0 Total forbs 77.1 f 3.8 65.3 f 8.3 25.5 f 5.4 1.7 f 1.3 0.2 f 0.2 Big sagebrush Amelanchier utahensis 3.7 f 3.0 11.1 f 3.5 20.2 f 8.5 27.1 f 5.8 44.8 f 5.4 Eriogonum microthecum 0.5 f 0.3 1.4 f 0.3 0.4 f 0.3 6.1 f 5.1 3.5 f 1.5 Symphoricarpos oreophilus 9.4 f 4.8 4.8 f 0.4 29.2 f 9.5 29.4 f 5.9 17.6 f 4.7 Other browse 2.1 f 1.5 1.5 f 0.5 5.5 f 4.6 2.0 f 0.7 5.6 f 3.0 Total forbs 84.2 f 5.9 80.5 f 1.8 44.7 f 2.5 35.4 f 6.5 28.4 f 1.4 Mixed browse Amelanchier utahensis 8.1 f 3.1 4.9 f 1.3 6.5 f 1.8 2.7 f 2.7 5.0 f I.5 Populus tremuloides 1.6 f 0.8 0.2 f 0.2 2.7 f 2.7 3.0 f 2.4 9.0 f 4.4 Quercus gambelii 6.0 f 1.9 9.3 f 5.0 15.7 f 7.4 30.9 f 18.9 24.5 f 8.1 Rosa wooa!sii 1.6 f 1.0 7.2 f 1.0 15.1 f 5.1 28.6 f 7.9 22.4 f 3.2 Symphortcarpos oreophilus 25.2 f 6.4 4.4 f 2.7 13.2 f 7.7 9.9 f 5.1 27.7 f 8.4 Other browse 1.2 f 1.2 1.1 f 0.8 1.1 f 0.9 2.6 f 2.4 0.6 f 0.6 Total forbs 55.6 f 6.4 72.3 f 5.1 45.7 f 11.7 20.7 f 9.2 7.5 f 0.8 Total grass 0.7 f 0.2 0.6 f 0.5 0.0 1.6 f 1.4 3.3 f 1.0

JOURNAL OF RANGE MANAGEMENT 38(2), March 1985 169 Table 3. Carcass chaneteristies of buck deer harvested in October (sample size in parentheses)

Subcutaneous fat Total number of antler points longer than 2-l/ 2 cm Eviscerated weight depth (% Total) Year (kg f SE,) (mm f SEm) 2 3-4 5+ l-1/3 1980 38.9 f 0.4 (46) 5.3 f 0.2 (60) 60 35 5 (68) 1981 38.0 f 0.3 (131) 3.7 f 0.3 (151) 35 64 1 (226) 1982 38.2 f 0.4 (108) 5.0 f 0.2 (87) 52 43 5 (176) 2-l/3 1980 50.2 f 2.6 (9) 10.7 f 0.5 (14) 0 65 35 (17) 1981 47.9 fl.O (19) 7.0 f 0.5 (22) 0 48 52 (31) 1982 50.6 f 1.7 (17) 6.1 f 0.6 (12) 0 27 73 (26) 3-l/3+ 1980 61.7 f 4.2 (6) 14.3 f 1.0 (12) 0 24 76 (17) 1981 53.4 f 1.8 (12) 8.5 f 0.9 (13) 0 20 80 (15) 1982 57.3 f 3.4 (3) 14.0 f 0.8 (2) 0 0 100 (7)

Discussion ditions (deep snow, low temperatures) would be expected less frequently and for short periods. Deer on these ranges simply do Our results from 4 plant communities indicated only the latter not appear to need the same degree of physical conditioning as part of the summer should be considered critical to mule deer or, required where winter ranges are more limiting. such ranges from a forage resources view. In May and June, forage The critical period, for mule deer on limited summer ranges of availability was high, deer diets contained many species, and per- cent dietary CP level was good (French et al. 1955, Magruder et al. relatively poor forage quality and where winter range is extensive, 1957, Urness 1973). However, by August and September, palatable appears to be late summer-early fall when only a few shrub species forage was greatly decreased and diets were comprised mainly of 1 account for most of the diet. Evaluation of availability and proper or 2 species. The Gambel oak and mixed browse communities utilization of those key species during that period would indicate provided adequate protein throughout the summer, whereas the potential carrying capacity based on forage availability. Utah serviceberry and big sagebrush communities provided only maintenance amounts in late summer (Murphy and Coates 1966, Literature Cited Holter et-al. 1979). Our late summer values for dietary CP con- Armstrong, D.M. 1977. Distributional patterns of mammals in Utah. trasted sharply with those reported from good summer ranges Great Basin Natur. 37:457-474. which generally exceed 12% (Wallmo et al. 1977, Collins and Austin, D.D. 1984.Fat depth at the xiphoid process-A rapid index to deer Urness 1983). Leaves began falling in mid-September and by mid- condition. Great Basin Natur. 44: 178-I 8 1. October the process was complete, indicating the value of the Austin, D.D., and PJ. Urness. 1976. Weights of hunter harvested mule deer in Utah. Utah Sci. 37: I I-13. summer range for storage of body fat and pre-winter conditioning Austin, D.D., and P.J. Umess. 1983. Summer use of bitterbrush rangelands was ended by October. by mule deer. p. 203-2 12. In: Proceedings-Research and Management of Forage quality on the summer range has been shown to affect Bitterbrush and Cliffrose in Western North America. Intermountain size and condition of harvested deer (Julander et al. 1961, Forest and Range Exp. Sta. Gen. Tech. Rep. INT-152. Robinette et al. 1973), overwinter survival (Richens 1967, Trout Deschnmp, J.A., PJ. Urness, and D.D. Austin. 1979. Summer diets of and Thiessen 1973), and subsequent reproduction (Jones et al. mule deer from lodgepole pine habitats. J. Wild]. Manage. 43:154-161. 1956, Swank 1958, Robinette et al. 1977, Pederson and Harper Collins, W.B., and PJ. Urness. 1983. Feeding behavior and habitat selec- 1978). Where summer ranges are limited, these effects would likely tion of mule deer and on northern Utah summer range. J. Wild]. be exacerbated due to reduced forage availability (Pederson 1970). Manage. 47646-663. Durrant, S.D. 1952. Mammals of Utah, and distribution. Univ. Consequently, reproduction, overwinter survival, and physical Kansas Publ., Mus. Natur. Hist. 61-549. condition of deer from summering areas of marginal quality would French, C.E., L.C. McEwen, N.D. Magruder, R.H. Ingram, and R.W. be expected to be lower than from those areas of good summer Swift. 1955. Nutritional requirements of white-tailed deer for growth and range. antler development. Pa. Agr. Exp. Sta. Bull. 600. Buck deer harvested in fall had lower eviscerated weight, fewer Holter, J.B., H.H. Hayes, and S.H. Smith. 1979. Protein requirement of antler points by age class, and contained less subcutaneous fat than yearling white-tailed deer. J. Wildl. Manage. 43:872-879. deer harvested from other areas containing lush and extensive Jones, D.A., W.L. Robinette, and 0. Julander. 1956. Influence of summer summer range. Therefore, deer entering the wintering period were range condition on mule deer reproduction in Utah. Proc. 36th Ann, in comparatively poorer condition, and consequently, higher mor- Conf. W. Ass. State Game & Fish Comm. Julander, O., W.L. Robinette, and D.A. Jones. l%l. Relation of summer tality due to winter stress would be expected. However, reproduc- range condition to mule deer herd productivity. J. Wildl. Manage. tion and overwinter survival were not significantly reduced. Fall 25:54-60. production averaged .80 fawns:doe on the Sheeprock Mountain Magruder, N.D., C.E. French, L.C. McEwen, and R.W. Swift. 1957. area (1979-83) with Utah statewide averaging .84 Utah deer units Nutritional requirements of white-tailed deer for growth and antler with limiting summer range averaged .82. Recruitment in spring development. II. Pa. Exp. Sta. Bull. 628. (1980-84) averaged .69 fawns:adult compared to the post-hunt Murphy, D.A., and J.A. Coates. 1966. Effects of dietary protein on deer. ratio of .76 on the study area:overwinter losses were not reported Trans. North Amer. Wild]. Nat. Resour. Conf. 31:129-139. except for the extremely harsh winter of 1981-82 where losses were Pederson, J.C. 1970. Productivity of mule deer on the LaSal and Henry minor. Mountains of Utah. Utah Div. Wild]. Res. Pub. 70-2. Pederson, J.C.,and K.T. Harper. 1978. Factors influencing productivity of We are thus led to conclude that the extensive winter range two mule deer herds in Utah. J. Range Manage. 31:105-l 10. associated with the Sheeprock area is adequate for sustaining deer, Poulton, C.E., and E.W. Tisdale. 1961. A quantitative method for the and significant losses that may be expected on areas of limited description and classification of range vegetation. J. Range Manage. winter range are much lower here. Tueller (1979) concluded year- 1413-21. long dietary nutrients were adequate for sustaining mule deer on Regelin, W.L., R.M. Bartman, D.W. Reichert, and P.H. Neil. 1976. The several similar ranges in Nevada. Also, since the desert winter influence of supplemental feed on food habits of tamed deer. USDA range is located at low elevations, extremely adverse weather con- Forest Serv. Res. Note RM-3 16.

170 JOURNAL OF RANGE MANAGEMENT 38(2), March 1985 Richens, V.B. 1967. Characteristics of mule deer herds and their range in Trout, L.E., and J.L. Thiessen. 1973. Physical condition and range rela- northeastern Utah. J. Wildl. Manage. 31:651-655. tionship of the Owyhee deer herd. Fish St Game Job. Rep. Proj. Robinette, W.L., C.H. Baer, R.E. Pillmore,and C.E. Knittle. 1973. Effects W-141-R-2. of nutritional change oncaptive mule deer. J. Wildl. Manage. 37:312-326. Tueller, P.T. 1979. Food habits and nutrition of mule deer on Nevada Robmette, W.L., N.V. Hancock, and D.A. Jones. 1977. The Oak Creek ranges. Nevada Dep. of Fish and Game Proj. Rep. W48-5. mule deer herd in Utah. Utah Div. Wildl. Res. Pub. No. 77-15. Urness, P.J. 1973. Chemical analyses and in vitro digestibility of seasonal Robinette, W.L., D.A. Jones, G. Rogers, and J.S. Gashwiler. 1957. Notes deer forages, Part II. In: Deer nutrition in chaparral and desert on development and wear for Rocky Mountain mule deer. J. Wild]. habitats. Rocky Mtn. Forest and Range Exp. Sta. Spec. Rep. No. 3. Manage. 21:134-153. Wallmo, O.C., L.H. Carpenter, W.L. Replin, R.B. Gill, and D.L. Baker. Swank, W. 1958. The mule deer in Arizona chaparral. Arizona Game & 1977. Evaluation of deer habitat on a nutritional basis. J. Range Manage. Fish Dep. Wild]. Bull. No. 3. 30:122-127.