Elk and Mule Deer Diets in North-Central New Mexico

Abstract

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...

Migratory plasticity is not ubiquitous among large herbivores

“…Further, studies have shown that bird populations with high migratory diversity tend to be more resilient to environmental change and population declines (Gilroy et al, 2016). The lack of migratory diversity may be one of the reasons why mule deer populations have generally declined in recent decades, while elk populations continue to flourish (Lindzey, Hepworth, Mattson, & Reese, 1997;Sandoval, Holechek, Biggs, Valdez, & VanLeeuwen, 2005). Thus, the spectrum of migratory diversity of large herbivores could range from species or populations that exhibit high rates of switching and low fidelity to routes, to those that do not switch behaviours and show strong fidelity to routes.…”

Mechanical fuel treatment effects on vegetation in a New Mexico dry mixed conifer forest

“…Many animals, such as deer and elk, rely on shrub production for a substantial part of their dietary needs. In central New Mexico, shrubs made up 32-61% of elk diets and 60-78% of deer diets in woodland habitats depending on the season (Sandoval et al, 2005). Although, we did not measure ungulate use of shrubs, ungulate use can be a limiting factor facing shrub regeneration and growth.…”

Mule Deer Habitat Selection Following Vegetation Thinning Treatments in New Mexico

“…However, as a treated area ages, fewer herbaceous forages become available during the growing season, which could potentially account for the avoidance of older treatments during summer. Transitioning into the winter season, deer predominately forage on nearly all browse species (Sowell et al 1985, Sandoval et al 2005), which is more abundant in older treated areas thus mirroring the increased odds of mule deer selection for 4‐year‐old treatments during winter.…”