Foraging niche overlap among Rocky Mountain elk (Cervus elaphus nelsoni), Rocky Mountain mule deer (Odocoileus hemionus hemionus), and cattle (Bos taurus) was studied for 2 years on 37 000 ha of nonforested foothill and mountain habitat in northwestern Wyoming. Microhistological analysis was used to quantify botanical composition of ungulate diets from monthly fecal collections. Feeding habitat use was determined through monthly surveys from fixed-wing aircraft to record nonsolitary animals in nonforested habitat. Kulcyznski's similarity index was used to calculate dietary and feeding habitat overlap among the 3 ungulates, and these 2 indices were multiplied together to estimate foraging niche overlap. In all seasons, elk and cattle consumed grass-dominated diets (mean ¼ 61% and 81%, respectively), although elk diets were more diverse. Mule deer consumed more forbs and shrubs than either elk or cattle (P , 0.10). Foraging niche overlap was high (45%) between mule deer and elk in spring. Cattle in summer and fall had !60% foraging niche overlap with elk in spring, indicating that, in spring, elk foraged in many of the same places (largely sagebrush grassland) and ate diets similar in botanical composition to what cattle did during summer and fall (principally Festuca idahoensis, Pseudoroegneria spicata, and Achnatherum spp.). Foraging niche overlap also was high (41%-51%) between elk in winter and cattle in summer and fall. Therefore, if competitive or complementary relationships existed between elk and cattle, these interactions most likely occurred on sagebrush grasslands where cattle use in summer-fall was followed by elk use in winter-spring. We recommend that resource managers focus their forage utilization and range trend monitoring in foothill sagebrush grasslands. ResumenSe estudió el traslape del nicho de forrajeo entre el alce de las Montañ as Rocallosas, (Cervus elaphus nelsoni), el venado mula de las Montañ as Rocallosas (Odocoileus hemionus hemionus) y el ganado (Bos taurus); el estudio se condujo por dos añ os en 37 000 ha de hábitats deforestado al pie de montañ a y montañ oso situados en el noroeste de Wyoming. La composició n botá nica de la dieta de los ungulados se determinó a partir de muestras fecales colectadas mensualmente y con el uso del análisis microhistoló gico. El uso de há bitat alimenticio se determinó a través de muestreos mensuales por medio de un dispositivo aéreo de alas fijas para registrar los animales no solitarios en el há bitat deforestado. El índice de similaridad de Kulcyznski se uso para calcular el traslape de la dieta y del há bitat alimenticio entre los tres ungulados, y estos dos índices se multiplicaron para estimar el traslape del nicho de forrajeo. En todas las épocas de añ o, el alce y el ganado consumieron dietas dominadas por zacates (media ¼ 61% y 81%, respectivamente), aunque las dietas del alce fueron má s diversas. El venado mula consumió más hierbas y arbustos que el alce y el ganado (P , 0.10). En primavera, el traslape del nicho de forrajeo fue a...

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Spring elk grazing may reduce forage availability for wildlife or livestock in summer and may harm forage resources on foothill rangeland. We quantified bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love) response to spring defoliation on foothill rangeland in southwestern Montana. Two experiments were conducted simultaneously on a foothill grassland site and a foothill sagebrush steppe site. Bluebunch wheatgrass plants (n 5 800) were selected and excluded from wild and domestic ungulates. Clipping treatments were applied in either early spring (mid-to late April) or late spring (mid-to late May), and plants were clipped to 1 of 3 residual heights (3, 6, or 9 cm) for 1, 2, or 3 successive years. Unclipped plants served as controls. Plant response was measured in late June and late July on both sites. April clipping for 3 successive years did not adversely affect bluebunch wheatgrass in June or July (P. 0.05) at either site. On foothill grassland, May defoliation to 3 cm for 2 consecutive years reduced leaf height (P 5 0.04) in July. May defoliation for 3 successive years to 3 or 6 cm reduced plant yield (P , 0.05) and leaf height (P , 0.05) in June, and May defoliation for 3 successive years to 3 cm reduced leaf height (P 5 0.02) in July. On foothill sagebrush steppe, 3 successive years of May defoliation to # 9-cm stubble heights decreased leaf height in June (P , 0.05). We conclude that foothill rangelands where bluebunch wheatgrass receives moderate or light defoliation (6-9-cm residual stubble heights) in mid-to late May should be limited to no more than 2 successive years of mid-to late May grazing, whereas sites that receive heavy to severe defoliation (# 3-cm residual stubble heights) in mid-to late May should not be grazed for 2 successive years during mid-to late May. Resumen El apacentamiento del alce en primavera puede reducir la disponibilidad de forraje en verano para la fauna silvestre o el ganado y dañ ar los recursos forrajeros de los pastizales de piedemonte. Cuantificamos la respuesta del ''Bluebunch wheatgrass'' (Pseudoroegneria spicata [Pursh] A. Love) a la defoliación en primavera en un pastizal de piedemonte del sudoeste de Montana. Se condujeron dos experimentos en forma simultánea, uno en un sitio de pastizal de piedemonte y el otro en un sitio de estepa de ''Sagebrush.'' Se seleccionaron plantas de ''Bluebunch wheatgrass'' (n 5 800) y se excluyeron de los ungulados dome´sticos y silvestres. Los tratamientos de corte se aplicaron a inicios de primavera (mediados a fines de de abril) o a fines de primavera (mediados a fines de mayo), las plantas fueron cortadas a una de tres alturas (3, 6, o 9 cm) durante uno, dos o tres añ os consecutivos, las plantas sin corte se utilizaron como control. La respuesta de la planta se midió a fines de junio y julio en ambos sitios. El corte en abril por tres añ os consecutivos no afectó adversamente al ''Bluebunch wheatgrass'' ni en junio ni julio en ninguno de los sitios (P. 0.05). En el pastizal de piedemonte, la defoliación de mayo a 3 cm por ...

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Learn how to achieve uniform utilization across pastures that are partially burned.