Botanical composition of mule deer and elk diets in winter, spring, summer, and autumn was studied during 1998 and 1999 on woodland rangeland in north-central New Mexico using microhistological analysis of fecal samples. Our study area had no livestock grazing for 60 years but was moderately grazed by mule deer and elk. Elk and mule deer shared 3 of the top 5 key forage species when diets were pooled across seasons and years. These 3 species were oak (Quercus sp.), ponderosa pine (Pinus ponderosa Dougl.), and mullein (Verbascum thapsus L.). When data were pooled across seasons and years, overall dietary overlap between mule deer and elk was 64%. Diet overlaps of 50% or more occurred between mule deer and elk in all 4 seasons in both years of study. Throughout both years, mule deer and elk diets were dominated by browse. Mountain mahogany (Cercocarpus montanus Raf.) was the most abundant browse plant in mule deer diets; ponderosa pine was most abundant in elk diets. Both animals selected forbs, which were in low supply during the study. Scarlet globemallow (Sphaeralcea coccinea Pursh), a nutritious forb, was common in both mule deer and elk diets. Our study and others from woodland rangelands in New Mexico show high potential for forage competition between mule deer and elk. Elk are more dietarily adaptable to changing forage availability than are mule deer. Our study indicates that diets of mule deer and elk are not complementary on woodland rangelands in New Mexico. Therefore, grazing capacity is not increased by common-use grazing of the 2 animals. Both mule deer and elk herds have been increasing on our study area. Therefore, if use of common forage species is kept at moderate levels on southwestern woodland rangelands, mule deer herds can be maintained or increased when elk are present. Resumen La composició n botánica de las dietas de invierno, primavera, verano y otoñ o de ciervos rojos (Cervus elaphus) y venados (Odocoileus hemonius) que habitan en los pastizales de monte del centro-norte de Nuevo México fue estudiada durante 1998 y 1999 utilizando aná lisis microhistoló gico delas heces. Nuestra á rea de estudio estuvo excluida del pastoreo bovino por 60 añ os pero recibió pastoreo moderado de venados y ciervos rojos. Los ciervos rojos y venados compartieron 3 de las 5 especies forrajeras claves más importantes cuando se analizaron las dietas combinadas de todas las estaciones y de ambos añ os. Estas tres especies fueron roble (Quercus sp.), pino ponderosa (Pinus ponderosa Dougl.), y barbasco (Verbascum thapsus L.). Cuando se combinaron los datos de todas las estaciones y añ os, el traslape de la dieta entre el ciervo rojo y el venado fue del 64%. El traslape de la dieta del 50% o má s ocurrio en las 4 estaciones y en ambos añ os de este estudio. A lo largo de ambos añ os, tanto las dietas de venados como las de ciervos rojos estuvieron dominadas por forraje ramoneable. Cercocarpus montanus Raf. (mountain mahogany) fue la especie arbustiva má s abundante en la dieta de venados, mientras que pino ponderosa...

Botanical composition of mule deer and elk diets in winter, spring, summer, and autumn was studied during 1998 and 1999 on woodland rangeland in north-central New Mexico using microhistological analysis of fecal samples. Our study area had no livestock grazing for 60 years but was moderately grazed by mule deer and elk. Elk and mule deer shared 3 of the top 5 key forage species when diets were pooled across seasons and years. These 3 species were oak (Quercus sp.), ponderosa pine (Pinus ponderosa Dougl.), and mullein (Verbascum thapsus L.). When data were pooled across seasons and years, overall dietary overlap between mule deer and elk was 64%. Diet overlaps of 50% or more occurred between mule deer and elk in all 4 seasons in both years of study. Throughout both years, mule deer and elk diets were dominated by browse. Mountain mahogany (Cercocarpus montanus Raf.) was the most abundant browse plant in mule deer diets; ponderosa pine was most abundant in elk diets. Both animals selected forbs, which were in low supply during the study. Scarlet globemallow (Sphaeralcea coccinea Pursh), a nutritious forb, was common in both mule deer and elk diets. Our study and others from woodland rangelands in New Mexico show high potential for forage competition between mule deer and elk. Elk are more dietarily adaptable to changing forage availability than are mule deer. Our study indicates that diets of mule deer and elk are not complementary on woodland rangelands in New Mexico. Therefore, grazing capacity is not increased by common-use grazing of the 2 animals. Both mule deer and elk herds have been increasing on our study area. Therefore, if use of common forage species is kept at moderate levels on southwestern woodland rangelands, mule deer herds can be maintained or increased when elk are present. ResumenLa composició n botánica de las dietas de invierno, primavera, verano y otoñ o de ciervos rojos (Cervus elaphus) y venados (Odocoileus hemonius) que habitan en los pastizales de monte del centro-norte de Nuevo México fue estudiada durante 1998 y 1999 utilizando aná lisis microhistoló gico delas heces. Nuestra á rea de estudio estuvo excluida del pastoreo bovino por 60 añ os pero recibió pastoreo moderado de venados y ciervos rojos. Los ciervos rojos y venados compartieron 3 de las 5 especies forrajeras claves más importantes cuando se analizaron las dietas combinadas de todas las estaciones y de ambos añ os. Estas tres especies fueron roble (Quercus sp.), pino ponderosa (Pinus ponderosa Dougl.), y barbasco (Verbascum thapsus L.). Cuando se combinaron los datos de todas las estaciones y añ os, el traslape de la dieta entre el ciervo rojo y el venado fue del 64%. El traslape de la dieta del 50% o má s ocurrio en las 4 estaciones y en ambos añ os de este estudio. A lo largo de ambos añ os, tanto las dietas de venados como las de ciervos rojos estuvieron dominadas por forraje ramoneable. Cercocarpus montanus Raf. (mountain mahogany) fue la especie arbustiva má s abundante en la dieta de venados, mientras que pino p...