LITERATURE REVIEW

Competition for forage between animal species occurs when two or more species prefer the same food items and the supply or area is limited. Several reviews of the literature have listed the numerous studies reporting on food habits of elk and deer (Capp 1968, Kirsch and Greer 1968, Kufeld 1973, Kufeld et al. 1973). Only a few studies, however, have attempted to identify competition on common-use winter range over a broad regional area, such as the Blue Mountains.

Working on the North Fork of the John Day River in the southern Blue Mountains, Cliff (1939) suggested that "feeding habits of mule deer and elk are quite similar in this region." He also observed that deer have a tenacious instinct to use customary feeding areas in winter but elk would seek out new areas of available for age in hard winters. Early studies of winter range in nearby Idaho also warned that increasing elk numbers presented a threat to resident deer populations (Case 1938).

Based on 3 years of data from analysis of stomach contents of elk and deer in Idaho and western Montana, DeNio (1938) showed that elk preferred winter diets consisting mainly of grasses but that mule deer preferred mainly shrubs and conifers. Availability of preferred species has been shown to influence the composition of elk and deer diets (Morris and Schwartz 1957). Cowan (1947) concluded from studies of feeding time on plants in Jasper National Park, Alberta, that elk were forcing mule deer to shift their winter diets from preferred browse to grass.

Studies of different densities of elk and deer on Blue Mountain winter range in southeastern Washington showed that high elk concentrations could inhibit recovery of the range but that competition for the principal bunchgrass species was probably not severe (Buechner 1952).

Studies of reproduction of both elk and deer have pointed out the several physiological responses that reduce densities of herds when shortages in the food supply become chronic (Buechner and Swanson 1955, Klein 1970, Robinette et al. 1977).

STUDY AREA

The physiographic province of the Blue Mountains of eastern Oregon and Washington is the second largest in the two-State area; the largest is the Columbia Basin which joins the mountain foothills on the north and west. It is at this interface that critical winter range exists (fig. 1). Within the mountains, however, are large, block-faulted valleys, the foothills of which also provide winter forage for more localized herds of elk and deer. Maximum migration of elk from the Columbia Basin winter range at 2,000 feet (600 m) elevation to high summer range at 8,000 feet (2 500 m) elevation is about 40 miles (65 km). Interior migrations are over elevation changes of 2,000 to 3,000 feet (600-900 m) and distances of 5 to 10 miles (8 to 16 km). Specific study sites shown in figure 1 are listed in table 1.

Grassland soils range from the lower prairie type chernozems of the Palouse formation to the shallow basalt lithosols of the intermingled upland forest openings. Forest soils are predominantly western brown forest soils with inclusions of windtransported pumicite from earlier volcanism in the Cascade Range.

Climate is influenced mostly by marine airmasses from the Pacific Ocean which furnishes precipitation having a winter high and a summer low. Along lower foothills and mountain valleys, precipitation is mainly rainfall in amounts of 10 to 15 inches (25-38 cm), with a spring peak in May. Fall rains initiate regrowth of grassland for age in about 3 out of 4 years. In the mountains, precipitation ranges between 20 and 40 inches (51-102 cm) and is largely in the form of snow that accumulates beginning in November.

In late fall, deer precede elk from the mountains to these winter ranges. Elk remain on the summer range into December, and it is often January before snow depth drives them down onto foothill winter range. Depending on spring "breakup" and initial growth of forage, elk begin migrating from winter range between mid-March and early April. Deer may linger longer, but both species are usually off winter range by late April. Normally, Blue Mountain winter ranges provide between 3 and 4

months of concentrated use by big game.

Foothill grasslands consist mainly of three associations, (1) the bluebunch wheatgrass/Sandberg bluegrass, (2) bluebunch wheatgrass/Idaho fescue, and (3) Idaho fescue/snowberry (Daubenmire 1970). Herbaceous species common to all study areas were: bearded bluebunch wheatgrass, cheatgrass, Idaho fescue, one spike danthonia, prairie junegrass, and Sandberg bluegrass. Forbs included balsam root, erigeron (fleabane), lomatium (biscuitroot), lupine, onion, rushpussytoes, stoneseed, and western yarrow. Shrubs included buckwheat (Wyeth eriogonum), chokecherry, rabbitbrush, rose, sagebrush, and snowberry.

Forest communities associated with these winter ranges include the (1) ponderosa pine/bluebunch wheatgrass, (2) ponderosa pine/Idaho fescue, (3) ponderosa pine/snowberry, and (4) ponderosa pine/ninebark (Daubenmire and Daubenmire 1968); components of the Douglas-fir/snowberry and

1scientific plant names are listed in the appendix.

Douglas-fir/pinegrass asso

ciations also exist in small amounts. In addition to many of the above grassland species, forest type herbaceous species included: cheatgrass, elk sedge, hawkweed, heartleaf arnica, letterman needleg rass, northwest sedge, pineg rass, rose pussy toes, Ross sedge, strawberry, western fescue, and western

needleg rass. Common shrubs of the forest were: chokecherry, creambush rock spirea, oceanspray, Oregon grape, and ninebark. Trees included: Douglas-fir, ponderosa pine, and western juniper.

The salient feature of winter range in and surrounding the Blue Mountains is that the classical type shrub communities often associated with other big-game winter range throughout the Rocky Mountains and intermountain west are absent.

METHODS

In consultation with the Oregon Department of Fish and Wildlife, Northeast Region, 5 winter range units of a possible 25 were selected to represent ranges having the highest probability for competition between deer and elk (fig. 1). Biologists managing wildlife on these areas were given material and sampling instructions for early and late winter collections of fecal pellets. Early sampling was done during the inventory of herd composition in December of 1973; the late season collection was from the same sampling sites but during March and April of 1974 when population trends were determined.

Field biologists gathered the freshest possible fecal pellet groups for each collection. Four groups each for elk and deer were collected from the five areas during early and late season for laboratory analysis. Samples were kept frozen from the time of collection until they were analyzed.

Analysis followed the technique of Sparks and Malechek (1968). Some modification in preparation of samples made material placed on microscope slides more color free. Pellets were put in a blender with ethanol and blended at low speed for 1 minute to homogenize the sample. The resulting solution was allowed to soak for 24 hours, and the ethanol was poured off. Fecal material was then dried in a forced air oven. When completely dry, the material was ground through an intermediate Wiley mill fitted with a 1-mm 2 screen. After the samples

were ground, they were soaked in water for 3 hours and put in a blender for 2 minutes at high speed. Samples were poured from the blender through a 200-mesh screen and washed in water to remove fine material. Three microscope slides were prepared from the washed material. fields on each of the three slides were the basis for observation.

Twenty

A factorial analysis of variance was applied to specific constituents making up most of

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