Browsing Journal of Range Management, Volume 40, Number 1 (January 1987) by Subjects
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Crude Terpenoid Influence on Mule Deer Preference for SagebrushSamples of current year's growth of leaves and stems were collected in February 1983 from basin big sagebrush (Artemisia tridentata Nutt. tridentata), Wyoming big sagebrush (A.t. wyomingensis Beetle and Young), mountain big sagebrush (A.t. vaseyana [Rydb.] Beetle), and black sagebrush (A. nova Nels.) on a mule deer (Odocoileus hemionus hemionus) winter range near Gardiner, Montana. Samples were from both lightly and heavily used plants (form classes) within each taxon. Crude terpenoids were separated into 3 groups: headspace vapors, volatile, and nonvolatile crude terpenoids. Compounds in each group are thought to stimulate the sensory organs of mule deer. Individual compounds were identified and quantified for comparison with preference ranks among taxa and between utilization form classes. Seven compounds were selected by discriminant analysis as indicators among the 4 taxa, with methacrolein + ethanol, ρ-cymene, and the sesquiterpene lactones the most probable preference determinants. Seven other compounds were found useful for separating plants within taxa into form classes. Chemical differences between the 2 form classes, however, were less distinguishable than were those among the 4 taxa.
Dietary Relationships Among Feral Horses, Cattle, and Pronghorn in Southeastern OregonManagement of sympatric ungulates on multiple use lands requires knowledge of how species exploit resources available to them. We examined seasonal food habits, dietary overlap, and dietary quality of sympatric feral horses (Equus caballus), cattle (Bos taurus),, and pronghorn (Antilocapra americana) in south-eastern Oregon from May 1979 through March 1981. Seasonal diets of each ungulate species were determined by microhistological analysis of feces. At least 88% of the mean annual diets of horses and cattle consisted of grasses. Principal species consumed by these ungulates were bottlebrush squirreltail (Sitanion hystrix (Nutt.) J.G.Smith), bearded bluebunch wheatgrass (Agropyron spicatum (Pursh) Scribn. & Smith), and Thurber needlegrass (Stipa thurberiana Piper). Because dietary overlap between horses and cattle was high each season (62-78%), we concluded a strong potential existed for exploitative competition under conditions of limited forage availability. Pronghorn diets consisted largely of woody sagebrush (Artemisia) species in fall and winter, and a mixture of forbs in spring and summer. Dietary overlap between horses and pronghorn varied from 7% (summer) to 26% (winter). Overlap between cattle and pronghorn varied from 8% (winter) to 25% (spring). These lower levels of overlap indicate a wider buffer between noncompetitive coexistence and exploitative competition. Pronghorn generally selected diets containing higher levels of crude protein (CP) and lower levels of acid-detergent fiber (ADF) than horses or cattle. We observed few differences in seasonal dietary quality between horses and cattle.
Elk, Mule Deer, and Cattle Habitats in Central ArizonaElk (Cervus elaphus) and mule deer (Odocoileus hemionus) distribution and use of habitats shared with cattle (Bos spp.) on a ponderosa pine (Pinus ponderosa)-bunchgrass range in central Arizona was examined. Cattle were removed from the range in 1961 and reintroduced in 1980. A 48-km survey route was driven through pastures containing cattle and through pastures without cattle to document the effects cattle had on native ungulates during the summers of 1981 and 1982. Location and number of elk, mule deer, and cattle observed along the route were recorded. Locations where animals were seen were used as sample sites to measure habitat variables: forest overstory, plant species composition, elevation, slope, exposure, and distance to water, fencing, meadow, cover, and draws. Distribution of elk and mule deer and habitats used by elk changed when cattle were introduced to the range. Significantly (P<0.05) fewer elk and mule deer were seen on pastures grazed by cattle than on pastures not grazed by cattle. Use of habitats by elk shifted from open mesic and silviculturally disturbed areas to more closed forest after cattle introduced. Use of habitats by deer was not altered when cattle were introduced to the range.
Seasonal Diets of Camels, Cattle, Sheep, and Goats in a Common Range in Eastern AfricaAlthough there have been several reports on the food habits of domestic herbivores in various semiarid regions of the world, there has been no previous report on the partitioning of forage resources by camels (Camelus dromedarius) and sheep (Ovis aries), goats (Capra hircus) and cattle (Bos indicus) using a common range. In the semiarid region of northern Kenya, the seasonal exploitation by these herbivores resulting from herding by the nomadic Rendille pastoralists makes the system for management of these rangelands very complex. Information on the food habits of animals utilizing a common range is important in offering a basis for assessing the usefulness of the range components to the animals. Consequently, food habits information becomes an important tool in making management decisions. Camels were predominantly browsers while cattle were predominantly grazers. Sheep and goats were intermediate feeders. Cattle browsed most during the 'green' season when the browse shoots were most abundant and easiest for their large mouth parts to harvest. Camels grazed most during the very dry season when most trees and shrubs had shed their leaves. The observed variations in food habits among the 4 herbivores suggest that they may require different management to obtain optimum production.