Nutritional quality of forages used by in northern Idaho

Item Type text; Article

Authors Alldredge, M. W.; Peek, J. M.; Wall, W. A.

Citation Alldredge, M. W., Peek, J. M., & Wall, W. A. (2002). Nutritional quality of forages used by elk in northern Idaho. Journal of Range Management, 55(3), 253-259.

DOI 10.2307/4003131

Publisher Society for Range Management

Journal Journal of Range Management

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Link to Item http://hdl.handle.net/10150/643655 J. Range Manage. 55: 253-259 May 2002 Nutritional quality of forages used by elk in northern Idaho

MATHEW W. ALLDREDGE, JAMES M. PEEK, AND WILLIAM A. WALL

Authors are Ph.D. candidate, Biomathematics Program, Statistics Department, North Carolina State University, Raleigh, N. C. 27695; professor, Department of Fish and Wildlife Resources, University of Idaho, Moscow, Ida. 83844; and Wildlife Biologist, Safari Club International, Herndon, Virg. 20170. At the time of the research the senior author was Research Assistant, Department of Fish & Wildlife Resources, University ofIdaho, Moscow, Ida.

Abstract Resumen

The nutritional quality (digestible energy, crude protein, and Se evaluo la calidad nutricional (energia digestible, proteina minerals) of 7 known elk (Cervus elaphus Linnaeus) forages was cruda y minerales) de 7 especies forrajes que se sabe que el alce assessed at 4 different time periods from May to November. (Cervus elaphus Linnaeus) las consume, la evaluacion se realizo 4 diferentes periodos de tiempo de Mayo a Noveembre. Las Species evaluated were elk sedge (Carex geyeri Boott), Kentucky en especies evaluadas fueron: "Elk sedge" (Carex geyeri Boott), bluegrass (Pea pratensis Linnaeus), western goldthread (Coptis "Kentucky bluegrass" (Poa pratensis Linnaeus), "Western occidentalis Nuttall), clover (Trifolium repens Linnaeus), service- goldthread" (Coptis occidentalis Nuttall), "Clover" (Trifolium berry (Amelanchier alnifolia Nuttall), redstem ceanothus repens Linnaeus), "Serviceberry" (Amelanchier alnifolia Nuttall), (Ceanothus sanguineus Pursh), and Scouler (Salix scoule- "Redstem ceanothus" (Ceanothus sanguineus Pursh) y "Scouler riana Barratt). Mineral concentrations generally met estimated willow" (Salix scouleriana Barratt). Las concentraciones de min- requirements for elk in all seasons, except sodium remained erales generalmente satisfacen los requerimientos estimados below requirements in all seasons. Crude protein in most para el alce en todas las estaciones, excepto sodio el cual per- species sampled was adequate for adult gravid or lactating cows manece abajo de los requerimientos en todas las estaciones. A throughout the year, although concentrations in graminoids fell traves de todo el ano la proteina cruda de la mayoria de las especies de plantas muestreadas fue adecuada para las hembras below requirements during August. Forage provided adequate prenadas o lactantes, sin embargo, en Agosto, las concentra- gravid or lactating cows only during May, digestible energy for ciones de proteina cruda de las gramineas cayo por abajo de los indicating potential deficiencies in summer and autumn. Elk requerimientos. El forraje proveyo de energia digestible adecua- must be selective of plant parts, plant taxa, and foraging habitat da para las hembras adultas prenadas o lactantes solo en Mayo, to gain adequate nutrition. In this area, summer and fall forage indicando deficiencias potenciales en verano y otono. Para tener quality may be critical to lactating cow elk. una nutricion adecuada el alce debe ser selectivo de las partes de la planta que consume, el genero de planta y el habitat de forra- jeo. En esta area la calidad del forraje en verano y otono puede ser critica para las hembras lactantes de alce. Key Words: Elk, Cervus elaphus, forage quality, nutrition, Idaho

forests in northern Idaho managed primarily for tim- Industrial and productivity (Cook in press). However, few studies have contain substantial populations of elk. These ber production described forage quality and attempt to relate this to the nutrition- forests contain a mixture of age classes of in a diverse al levels that elk experience. mosaic of successional patterns. However, they do not provide We examined nutritional quality of primary elk forages in an large blocks of mature timber for security cover and road densi- industrial forest. We build on the substantial number of elk habi- ties are high, causing them to fall outside of the suitable criteria tat use investigations in northern Idaho showing the importance for elk habitat developed by Leege (1984). of seral communities as foraging areas. Substantial knowl- Elk presumably select habitats that have high quality, abundant edge of food habits and responses of forage to logging and forage, or provide cover (Patton 1974, Edge et al. 1988, Thomas burning is also available for this area to pursue the analyses. al. 1979). Nutritional quality of available forages may change et Specific objectives were to (1) assess the variability in digestible with phenological stage, between vegetation classes, aspect, and energy, crude protein, and mineral concentrations of known elk overstory structure (Irwin and Peek 1979). Nutrition is assumed forages across seasons and topographical aspect; (2) determine be a primary factor influencing elk distribution, abundance, to seasonal trend in nutritional quality by species and vegetation class; and (3) compare nutritional quality of representative forage

Authors wish to thank J. G. Cook , P. J. Heglund, R. K. Steinhorst , and C. J. species with the daily nutritional requirements of elk. Williams for their advice. K.L. Launchbaugh extended use of her lab for the nutri- tional analysis. J. Scott and B. Knapton provided invaluable field assistance. Research was funded by Potlatch Corporation, Rocky Mountain Elk Foundation, Study Area and the University of Idaho. This is University of Idaho, College of Natural The study area was located west of the Dworshak Reservoir in Resources Journal Series Paper Number 956. the North Fork of the Clearwater River drainage, in Clearwater Manuscript accepted 7 Sept. 01. County, Ida. (45°N, 116.15°W). Mild summers and long-cold

JOURNAL OF RANGE MANAGEMENT 55(3) May 253 winters characterize the climate in the area study area received over 30,000 hunter- tent, and macro- and micro-element con- (Hansen et al. 1989). Annual precipitation days use in recent years (Idaho Department centrations. is 93.6 cm with the majority falling as of Fish and Game 1999). Alldredge (1999) The IVDMD was determined using the snow from November through February. reported that elk foraged in areas that had Tilley and Terry (1963) technique as mod- Western Red Cedar-Pachistima (Thuja pli- been logged within the past 20 years, ified by Pearson (1970). Ancom filter bags cata Donn-Pachistima myrsinites except during the rifle hunting season, were used to contain the material during Rafinesque) habitat type dominates the when they switched to mature fermentation. In-vitro-dry-matter-diges- area (Daubenmire and Daubenmire 1968). cover, confirming the general pattern tion was terminated after 48 hours for all Alldredge et al. (2001), Cooper et al. observed by Hash (1973), Hershey and trials. To reduce variability in the lab pro- (1987), Crookston and Stage (1999), Irwin Leege (1984), Irwin and Peek (1983b, cedure, rumen inoculum was obtained and Peek (1979), Moeur (1985), and Stage McLean (1972), and Unsworth et al. from a single Hereford cow maintained on (1973) have described the successional (1998) in northern Idaho. a constant alfalfa diet and all analyses patterns, species composition, and produc- were done within a 2 month period. tivity of this habitat type in northern Estimates of gross energy were deter- Idaho. Methods mined for 2 samples for each species with- Logging since the 1920's has created a in each time period using bomb calorime- variety of seral stands from clearcuts to Collections try. Digestible energy was determined for closed-canopy forests. Approximately We selected graminoids, forbs, and all samples collected by approximating 14% of the area is a recently cut, grass/low known to be important in the elk digestible energy as the product of shrub community. Kentucky bluegrass diet in the area (Irwin and Peek 1983a, digestibility and gross energy (Hobbs et al. (Poa pratensis L.), elk sedge (Carex gey- Kingery et al. 1996, Leege 1969, Leege 1982, Robbins 1983). Crude protein was eri Boott), pearly everlasting (Anaphalis and Godbolt 1985, Nelson and Leege estimated as 6.25 times the percent nitro- margaritacea L.), fireweed (Epilobium 1982, Young and Robinette 1939). Elk gen content (A.O.A.C.1984). angustifoliums L), senecios (Senecio trian- sedge, Kentucky bluegrass, western The organic and mineral composition of gularis Hooker), pentstemons (Pentstemon goldthread, clover, serviceberry, redstem the 7 selected forage species was estimat- spp Mitch.), pinegrass (Calamagrostis ceanothus, and Scouler willow were col- ed across seasons and years. Organic con- rubescens Buck.), wild strawberry lected to represent the variety of species stituents of carbon (C), nitrogen (N), and (Fragaria vesca L.) were common forbs used by elk and abundant in the study sulfur (S), were determined using a com- and graminoids. Clover (Trifolium repens area. bustion technique (McGeehan and Naylor L.) commonly occurred along access Collections for all of these species were 1988). Atomic emission spectroscopy routes that had been reseeded. A tall made on 3 sites in 6 areas in mid-June, (Anderson 1996) was used to determine shrub/grass community occupied 36% of mid-August, and mid-November, concentrations of aluminum (Al), cadmi- the study area. Mountain maple (Acer 1997-1998 and May 1998. Clover became um (Cd), calcium (Ca), chromium (Cr), glabrum Torrey), redstem ceanothus completely desiccated and unavailable in cobalt (Co), copper (Cu), iron (Fe), lead (Ceanothus sanguineus Pursh), serviceber- November. Plants were collected on north (Pb), molybdenum (Mo), potassium (K), ry (Amelanchier alnifolia Nuttall), and and south aspects to represent different phosphorus .(P), magnesium (Mg), man- Sitka alder (Alnus sinuata Rydberg) were light and moisture conditions, in the cedar- ganese (Mn), sodium (Na), nickel (Ni), common shrubs, with similar graminoids pachistima habitat type. sulfur (S), vanadium (V), and zinc (Zn). and forbs. Open-canopy conifer communi- Current year's growth of shrubs, and We used multiple analysis of variance ties comprised 21% of the area, with above-ground portions of graminoids and (MANOVA) to assess the variability in Douglas fir (Pseudotsuga menziesii forbs were collected for analysis. The nutrient quality by aspect, time, species, Franco) being the most common . entire twig of current year's growth, and vegetation class. Vegetation class Understories were more sparse, and shade including except in November was (graminoids, forbs, shrubs) was examined tolerant species including mountain maple, collected for shrubs, and graminoids and because these differences could affect thimbleberry (Rubus parviflorus Nuttall), forbs were clipped to within 1 cm of the cover type use. Trends in nutritional qual- Scouler willow (Salix scouleriana ground. Approximately 200 g per species ity of each forage species were examined Barratt), pachistima, huckleberries per site were collected. Samples also con- to determine if they met the requirements (Vaccinium membranaceum Douglas, V. sisted of collections from multiple plants of elk. Crude protein and digestible energy globulare Rydberg), and menziesia to account for variation between plants. concentrations by species and vegetation (Menziesia ferruginia Smith ) were com- class were compared to estimated daily mon. Common understory species includ- requirements in Forage Analysis of an elk (Cook press), ed western goldthread (Coptis occidentalis across time periods, using a t test. Samples were oven-dried at 40°C for 48 Nuttall), twinflower (Linneaea borealis Estimates of digestible energy and crude hours, ground with a Wiley Mill through a L.), Solomon seal (Smilacina stellata L.), protein were based on an adult cow, 1 mm screen, and stored until analysis. and bedstraw (Gallium triflorum Michx). gravid in spring and lactating through This temperature was selected to ensure Closed-canopy forests containing very mid-autumn, with average consumption that fermentable carbohydrates were sparse understories of shade-tolerants rates, daily activities, and metabolic retained, at the risk of reduction of cell comprised 29% of the area. demands. Mineral concentrations were solubles (Wolf and Carson 1973). Potlatch Corporation managed 40.6%, also compared to mineral requirements for Analyses included in-vitro-dry-matter- Idaho Department of Lands 32.1 %, and (National Research Council 1996), digestibility (IVDMD), gross energy con- U.S. Forest Service 18.8% of the area. The using a t-test.

254 JOURNAL OF RANGE MANAGEMENT 55(3) May 2002 Results all forage species during any single time met requirements in June. By August crude period. Elements toxic to animals, such as protein of redstem ceanothus and clover Cd and Pb, were present at low levels exceeded requirements, as did western A total of 114 and 160 vegetation sam- throughout all seasons in all forage goldthread in November. Protein levels in ples were collected during 1997 and 1998. species. forbs and shrubs met requirements for elk Seasonal collections were made within 2 in all seasons except for shrubs in days of the same date each year. No sig- November. Levels of protein in graminoids nificant differences in energy, mineral Crude Protein met elk requirements only in May. In concentrations or protein were related to Crude protein levels in all species declined from May through November August crude protein levels in graminoids, aspect. were (Table 2). In May crude protein concentra- elk sedge, and Kentucky bluegrass significantly lower than elk requirements (t 3 were over Minerals tions in all shrubs and clover 24%, higher than other species across all >3.4,P=0.01,P=0.01, andP<0.0001, in species Mineral concentrations all collection periods, except western respectively). Crude protein concentrations were variable with no predictable seasonal in Kentucky bluegrass and redstem cean- goldthread in November. Crude protein in patterns (Table 1). Molybdenum, Co, and western goldthread was lower than all othus were significantly below require- Ni concentrations were below detectable (t other species early in the year but smaller ments during November > 2.83, P < limits. Significant differences were detect- declines throughout the year relative to 0.0001 and P = 0.04, respectively). ed (P < 0.001) for time*species and other species resulted in high levels in time*vegetation class interactions, indicat- November. Digestible Energy ing a high degree of variability in mineral A similar pattern was observed in levels Digestible energy declined from May concentrations. Forage species provided of crude protein by vegetation class (Table through November, with some species sufficient concentrations of required min- 2). Protein concentrations in graminoids increasing from August to November erals above levels necessary to meet ani- were lower than in other vegetation class- (Table 3). Western goldthread showed the mal requirements for all seasons (t > 2.92, es. Shrubs had higher levels than forbs in largest increase in digestible energy P < 0.02), with the exception of Na. The May and June, were similar in August, and between August and November, but highest Na level in any forage species was lower than forbs in November. Significant Scouler willow, redstem ceanothus, and 91 pig/g, well below estimated minimum differences in crude protein concentrations serviceberry also increased between these Na requirement for cattle of 600 pglg. were detected within species and vegeta- times. Western goldthread had the highest Some forage species, including Mg and tion classes between collection periods (P levels of digestible energy for all seasons. K, provided concentrations of some min- < 0.05, Table 2). Scouler willow had the lowest levels for erals above the maximum tolerable limits All species provided adequate protein for all periods except November, where it had during certain time periods. No mineral elk in May, but only redstem ceanothus, one of the highest concentrations. Elk exceeded the tolerable limits for elk across Scouler willow, serviceberry, and clover sedge and Kentucky bluegrass had the

Table 1. High and low mineral concentrations found in forage species and estimated elk requirements (Cook in press, National Research Council 1984) of macro and micro elements (bdl = below detectable levels, and N/A = not available). Concentrations reported in µg/g. Values are averages of min- eral concentrations within a given time period. MANOVA detected significant differences (P < 0.001) for *timespecies and time* vegetation class interactions. All centrations of required minerals except Na were above required levels for all seasons (t > 2.92, P < 0.02). Co, Mo, and Ni concentra- tions were below detectable limits.

Required Clover Goldthread Elk sedge Bluegrass Redstem Serviceberry Scouler Willow

Al N/A 52-338 66-302 65-505 72-255 71-191 25-308 201-715 Cd N/A 0.2-0.5 0.1-0.3 0.04-0.9 0.2-1.7 0.1-0.4 0.1-1.3 0.1-1.3 Ca 1600-5800 9,683-13,780 2,467-13,750 5,608-11,367 2,983-10,217 7,167-13,200 3,450-8,950 12,000-14,283 Cr N/A Bdl-0.3 0.1-1.0 0.1-0.8 0.3-0.8 0.1-0.5 bdl-0.4 0.5-0.7 Co 0.07-0.11 bdl`-0.4 bdlc-0.2 bdlc-0.2 0.1-2.8 bdlc-0.1 bdlc-0.2 0.6-1.7 Cu 4-10 5.0-12.9 6.0-7.1 4.6-7.2 4.0-9.8 3.6c-9.6 6.0-8.1 6.5-12.7 Fe 50-100 111-220 113-321 111-230 98-163 107-195 10c-110 29-201 Pb N/A 6-56 11.5-234 17-150 29-245 1.1-39 3.3-111 0.9-19 Mg 500-2500 2,500-3,708 1,562-3,267 1,228-2,217 1,267-2,717 1,231-2,842 1,333-1,650 2,100-4,467b Mn 20-50 241-414 78-195 205-493 300-413 748-143 143-453 97-302 Mo 6a Bdl-0.2 0.3-1.1 Bdl-1.3 bdl bdl-0.4 bdl-2.0 bdl-0.2 Ni N/A 0.06-1.8 0.1-1.3 0.3-2.4 0.2-4.1 bdl-1.3 0.2-3.5 1.6-3.8 K 5000-7000 9,867-26,750 11,408-31,500b 11,408-19,833 7,308-16,417 9,392-20,083 5,217-31,500b 10,092-32,833b P 1700-3900 3,267-5,633 2,375-3,817 1,260-4,525 970-5,258 1,273-3,250 1,633-2,733 1,767-3,000 Na 600-1000 19c-45c 32c-92c 30c-71c 27c-63c 25c-50c 27c-39c 20c-81c S 800-1500 857-2,142 1,588-2,258 1,143-2,358 913-3,133 880-1,983 663-2,075 1,382-2,083 V N/A 0.1-1.3 0.3-2.3 0.1-2.7 0.1-1.8 0.2-2.3 0.5-2.5 0.4-3.5 Zn 20-40 37-58 28-100 27-39 21-136 18c-73 22-42 30-109 ano specified requirement, but a maximum tolerable value was known. econcentrations of the given element exceed the maximum tolerable limit. `concentrations of the given element do not meet the minimum requirements.

JOURNAL OF RANGE MANAGEMENT 55(3) May 255 Discussion Table 2. Crude protein concentrations (percent) for all species and vegetation classes across all time periods, with corresponding 95% confidence intervals. Required levels from Cook (in press). The high degree of variability in mineral concentrations observed in this study Species! might be expected. Differences between Vegetation Class May June August November vegetation classes are typical due to differ------(%)------ent cell-wall components (Short 1981). Forbs 18.7±13.2N 15.8±10.7 2.6A Other studies have documented a high Clover 24.3 ± 19.7±8.1 degree of variability in plant mineral con- Western goldthread 13.0 ± 3.9 11.8±6.2 centrations associated with soil type, pre- Graminoids 17.8 ± 6.5A'N 11.6 ± 6.9 4.7A'N cipitation, and weather conditions (Poole Elk sedge 16.0 ± 11.2±7.2 3.6 6.7A'N al. 1989, 1999). Spring weather Kentucky bluegrass 19.7 ± 12.0 ± 7.5 et Beaver conditions can affect the timing of growth Shrubs 26.5 ± 8.3N 20.5 ± 9.2N 1.8 6.5A'N initiation. This, along with subsequent Redstem ceanothus 29.5 ± 23.9 ± 5.8N 8.0A'N weather conditions could affect the pheno- Scouler willow 24.2 ± 19.8 ± 6.7N Serviceberry 25.9 ± 10.3N 14.9 ± 9.8 logical stage of plants throughout the growing season. Favorable growing condi- Requirements 7.5 15 AEstimate tions may be conducive to greater mineral significantly different than estimate in August (P < 0.05) Estimate significantly different than estimate in November (P < 0.05). absorption (Beaver 1999). The importance of minerals to the prop- er biological function of animals is well lowest levels of digestible energy of all 1,900 kcals/kg in August. Western recognized (Underwood 1977, Robbins species in November. Levels of digestible goldthread, the only forb measured during 1983, Van Soest 1994), but often neglect- energy were more similar for all species November, contained about 3,300 kcals/kg ed in studies of large herbivores (Cook in during August. Significant differences in digestible energy. Between mid-June and press). Results from this study indicate digestible energy were detected within mid-August, digestible energy content in that elk mineral requirements are generally (P species between collection periods < graminoids fell below shrubs. Significant provided for. Mixing of forage species 0.05) (Table 3). differences in digestible energy concentra- probably compensates for deficiencies and Seasonal trends in digestible energy lev- tions were detected within vegetation for concentrations in certain species that (P els by vegetation class were similar (Table classes between collection periods < are too high. 3). Graminoids declined from 3,100 0.05, Table 3). Sodium, which averaged only 1/10 or kcals/kg to 1,450 kcals/kg between May All species and vegetation classes met less of the daily nutritional requirements and November. Digestible energy of estimated digestible energy requirements (estimates for beef cattle), is the cation of shrubs was highest in May at 3,200 of elk during May. Digestible energy lev- the extracellular environment, it is impor- kcals/kg, lowest in August at just over els for all species and vegetation classes tant for regulation of body fluid volume 1,800 kcalslkg, and moderate (2,000 were significantly below requirements (t> and osmolarity, acid-base balance and tis- kcalslkg) in November. Forbs also 3.61,P < 0.05) during June, August, and sue pH, muscle contraction, and nerve declined through the seasons from almost November, except for western goldthread impulse transmission (Robbins 1983). 3,500 kcalslkg in May to slightly over in November. Thus, without sufficient amounts of sodi- um, elk growth and reproduction could be Table 3. Digestible energy levels (KcaLfkg of forage) for all species and vegetation classes across all depressed. However, elk may be obtaining time periods, with corresponding 95% confidence intervals. Required levels from Cook (in sodium from other sources than forage press). consumption, such as mineral licks and water (Weeks and Kirkpatrick 1976, Species! Robbins 1983). Vegetation Class May November Toxic elements were also found in the (Kcal!kg)) ------forage analyzed. Detrimental effects of J , A 177A'N Forbs 3,454 ± 182 ,N 285N 42 195J'A toxic elements, such as lead and cadmium, Clover 3,236 ± 2,146±184 188J'A'N 105A'N are related to the magnitude of the concen- Western goldthread 3,672 ± 2,567 ± 377N 42 tration within the body. Cadmium levels 120J'A'N 105A'N Graminoids 3,141 ± 2,337 ± 144 136 143J'A'N 139A'N appear quite low and are similar to levels Elk sedge 2,980 ± 2,298 ± 175 04 57J'A'N 160A'N that are in domestic animal feeds Kentucky bluegrass 3,301 ± 2,375 ± 226 160 246J°A,N (Underwood 1977). However, lead con- Shrubs 3,195 ± 1,915 ± 156 187 76 146J,A,N centrations were much higher and were Redstem ceanothus 3,497 ± 2,013 ± 181 223 114 423J,A,N similar to levels reported from pastures Scouler willow 2,601 ± 1,565 ± 261N 317 154 93J,A,N rich in lead or areas near lead mines Serviceberry 3,488 ± 1,973±129 109 (Underwood 1977). Whether these levels Requirements 2,200 3,000 would produce a toxic effect was not JEstimate significantly different than estimate in June (P < 0.05) AEstimate significantly different than estimate in August (P < 0.05) determined. NEstimate significantly different than estimate in November (P < 0.05). Percent crude protein in forage species

256 JOURNAL OF RANGE MANAGEMENT 55(3) May 2002 steadily declined from May through November, failed to provide for elk (Hanley et al. 1989). Several studies have November, a commonly reported pattern requirements after May, and were most demonstrated that both natural and man- (Cook in press). We also found that shrubs deficient in graminoids after mid-summer. made openings in forest canopies result in had higher concentrations of crude protein These patterns suggest elk should shift dramatic increases in forage production than graminoids. This may be an area-spe- from grass/low shrub areas to areas with (Patton 1974, Lyon and Jensen 1980, cific relationship as Urness et al. (1983) greater shrub development as seasons Riggs et al. 1990). Maximum annual shrub reported higher levels of protein in progress. In Colorado grasses provided biomass productivity occurs between 7 graminoids than shrubs, but others have more digestible energy on winter range and 14 years after overstory removal reported the opposite (Everitt and than shrubs (Hobbs et al. 1981). However, (Alldredge 1999) and total shrub biomass Gonzalez 1981, Meyer et al. 1984). Hobbs our results for November suggest that was greatest 10 to 14 years following har- et al. (1981) reported that grasses typically shrubs provide more digestible energy vests within the cedar-hemlock zone of had lower concentrations of crude protein during this period. northern Idaho (Irwin and Peek 1979). than shrubs during winter. However, our Estimates of digestible energy indicate Changes in habitat use from early summer results indicate that crude protein in that requirements of gravid cow elk are to fall indicate that forage quality may be graminoids is significantly lower than in provided for in May, but moderate to a factor driving habitat selection as areas shrubs during August, but only slightly severe deficiencies exist for lactating cow used in both periods have large quantities lower in November. elk during the entire summer. Studies with of forage. During summer, elk forage in open captive elk indicate that lactating cow elk Many studies indicate that elk habitat areas where abundant new-growth pro- cannot be maintained (J.G. Cook personal use should switch during the fall to areas vides ample nutrients (Martinka 1969, communication) nor can elk calves grow with conifer over-stories because vegeta- Edge et al. 1988, Leege 1984). McLean (Cook et al. 1996) on diets with the low tion in these areas remains succulent (1972) and Hash (1973) reported elk using levels of digestible energy we report. (Stehn 1973, Biggins 1975, Schoen 1977, shrubfields throughout late summer and Digestible energy is commonly a limiting Irwin and Peek 1983b, Wisdom and Cook fall in northern Idaho. Movement to secu- component of ungulate diets from mid- 2000). However, forage quantity in conifer rity areas of closed-canopy cover types summer through winter on many western stands is very low. Graminoids and forbs during hunting seasons is evident in other large-ungulate ranges (Cook, in press, are rare and total annual shrub productivi- areas as well (Morgantini and Hudson Parker et al. 1999). Loss of condition on ty, including unpalatable species, is only 1980, Unsworth and Kuck 1991, Hurley winter range is expected as nutritional lev- 50 kg/ha, 5 to 10 times lower than early 1994). els of winter forage decline below the successional areas (Alldredge 2001). Such Estimates of crude protein levels from requirements for maintenance (Hobbs et low forage biomass may limit foraging May through November generally provid- al. 1981, Cook in press). efficiency as instantaneous intake rates ed for the requirements of elk. Small defi- Nutritional deficiencies can have serious decrease and travel rates are elevated ciencies could be overcome via selective effects on the reproductive capabilities of (Wickstrom et al. 1984). Low foraging foraging. For example, elk could select elk. Thorne et al. (1976) related poor con- efficiency may account for avoidance of leaves and terminal ends of twigs to over- dition to low birth weight, which resulted conifer- dominated habitats as key forag- come small deficiencies (Blair and Epps in a low probability of calf survival. Poor ing areas (Collins and Urness 1983) 1967, Dietz 1972). However, the higher condition has resulted in delayed ovulation because lactating cow elk would not be the level of selective foraging to meet and breeding (Verme 1969), failure to able to consume sufficient forage to meet requirements results in a greater propor- ovulate, resorption of ovum, and failure to daily nutritional requirements (Cook in tion of total forage that is "unavailable." conceive (Trainer 1971). Failure to breed press). Significant deficiencies, such as those as a result of poor condition was reported observed for all graminoids in August, for caribou (Rangifer tarandus, Cameron might not be overcome by diet selection. 1994) and elk (Trainer 1971, Cook 2000). Management Implications By August, crude protein of graminoids Pregnancy rates of elk as low as 70% in was so low that losses of endogenous body some areas of Idaho (Gratson and Zager Our nutrition data indicate that elk for- protein associated with digesting them 1999) and 55% in western (Stussy ages provide adequate levels of minerals would equal or exceed any gain (Hobbs et 1993) have been reported. These low preg- and probably protein over the summer and al. 1982). The crude protein deficiencies nancy rates are probably due to inadequate autumn. However, digestible energy defi- we observed for graminoids in August nutrition on summer and autumn ranges. ciencies over an extended period of time indicate that elk could not restrict their Low levels of digestible energy reported warrants concern, especially in relation to diet to them and maintain endogenous in our study could result in reproductive potential effects on herd productivity. Our body protein. Maintenance of dietary pauses, slow calf growth over summer and data only provide a measure of the mixes is a means of achieving energy and autumn, and increased winter mortality digestible energy available to elk, and protein requirements (Hobbs et al. 1981, because condition in autumn may be rela- does not indicate actual digestible energy Otsyina et al. 1982). Low crude protein tively poor, especially as the effects of low content of diets. Thus, conclusions about levels in graminoids coincide with the nutrition accumulate across years. the effects on their nutritional condition period when elk have shifted from Foraging efficiency is an important fac- and productivity are avoided. At the least, grass/low shrub areas to areas dominated tor influencing cover type use (Collins et the data indicate that elk must be highly by shrubs (Alldredge 1999). al. 1978, Irwin and Peek 1983b). Both selective of plant parts, plant taxa, and Digestible energy levels of forage quantity and quality of forage are factors habitats where they forage, if they are to declined steadily from May through influencing cover type use patterns

JOURNAL OF RANGE MANAGEMENT 55(3) May 257 achieve adequate digestible energy intake. Beaver, D. E. 1999. Habitat use and patch Hansen, H. J., R. C. Martin, and G. A. Therefore, we speculate that much of the selection by in a sagebrush-steppe Meuleman. 1989. Phase II, wildlife protec- forage available to them is of little value, environment of southeast Idaho. M. S. tion, mitigation, and enhancement planning, Thesis, Univ. of Idaho, Moscow, Ida. Dworshak Reservoir. Contract, DI-I79- and is "carrying capacity" probably con- Biggins, D. E. 1975. Seasonal habitat relation- 88BP92631, Draft report, Idaho Dept. Fish siderably lower than would be predicted ships and movements of the Spotted elk and Game, Boise, Ida. based only on forage biomass. Our data herd. M. S. Thesis, Univ. of Montana, Missoula, Hash, H. S. 1973. Movements and food habits also suggest a nutritional environment that Mont. of Lochsa elk. M. S. Thesis, University of is marginal in its ability to provide for the Blair, R. M. and E. A. Epps, Jr. 1967. Idaho, Moscow, Ida. summer-fall digestible energy needs of Distribution of protein and phosphorus in Hershey, T.J. and T.A. Leege. 1984. Elk spring growth of rusty blackhaw. J. Wildl. movements and habitat use on a managed cow-calf pairs. We would predict relative- Manage. 31:188-190. forest in northcentral Idaho. Idaho Dept. of ly strong density-dependent relations in Cameron, R. D. 1994. Reproductive pauses by Fish & Game Wildl. Bull. 10. such an environment, because a potential- female caribou. J. Mamma1.75:10-13. Hobbs, N. T., D. L. Baker, J. E. Ellis, and D. ly small portion of the forage base appar- Collins, W. B. and P. J. Urness. 1983. M. Swift. 1981. Composition and quality of ently is actually of value to elk. Further, Feeding behavior and habitat selection of elk winter diets in Colorado. J. Wildl. we would predict that under these margin- mule deer and elk on northern Utah summer Manage. 45:156-171. range. J. Wildl. Manage. 47:646-663. al conditions that landscape-scale forest Hobbs, N. T., D. L. Baker, J. E. Ellis, D. M. Collins, W. B., P. J. Urness, and D. D. Swift, and R. A. Green. 1982. Energy and management practices that influence for- Austin. 1978. Elk diets and activities on dif- nitrogen based estimates of elk winter range age quality and quantity will have substan- ferent lodgepole pine habitat segments. J. carrying capacity. J. Wildl. Manage. tial long-term influences on these elk. Wildl. Manage. 42:799-810. 46:12-21. Although causes are unknown, elk herds Cook, R. A. 2000. Nutritional influences on Hurley, M. A. 1994. Summer-fall ecology of of the Clearwater basin in north-central breeding dynamics in elk. M.S. Thesis, Univ. the Blackfoot-Clearwater elk herd of western of Idaho, Moscow, Ida. Idaho have experienced declines in calf Montana. M. S. Thesis, Univ. of Idaho, Cook, J. G. In press. Nutrition and food habits. Moscow, Ida. in recruitment and subsequently declines pp 000-000 In D. E. Toweill and J. W. Idaho Dept. Fish and Game. 1999. Statewide herd size of about 25% over the last Thomas, (ed.), Elk of : 2nd surveys and inventory. Federal Aid in Wild!. decade (Gratson and Zager 1999). Our Ecology and Management. ed. Restoration Project, W-170-R-22 progress data suggest that nutrition, perhaps via Smithsonian Inst. Press, , D.C.. report. Boise, Ida. density dependent mechanisms, should be Cook, J. G., L. J. Quinlan, L. L. Irwin, L. D. Irwin, L.L., and J. M. Peek. 1979. Shrub pro- Bryant, R. A. Riggs, and J. W. Thomas. suspected as a potential contributor to duction and biomass trends following five 1996. Nutrition-growth relations of elk logging treatments within the cedar-hemlock these declines. calves during late summer and fall. J. zone of northern Idaho. Forest Sci. Our data support the contention that a Wildl. 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