Diets of desert mule deer in altered habitats in the lower Sonoran Desert

We conducted microhistological analyses of feces to identify diets of desert mule deer (Odocoileus hemionus eremicus) in four areas of central and western Sonora, Mexico, to evaluate seasonal variation in forage classes, and compare diets of mule deer and cattle in altered habitat with buffelgrass (Cenchrus ciliaris). For mule deer, we identified 96 plant species, 69 of which have not previously been reported as forage for this wild herbivore. From these species, 44 occurred in the mule deer diet greater than or equal to 1%. Browse was the most important forage class consumed by mule deer at all study areas (77-88%). Forbs comprised an average of 5-10% of the diet of mule deer among all areas. Use of succulents was highly variable among areas, but chainfruit cholla (Opuntiafulgida) occurred consistently in all areas and most seasons. Grass species were consumed the least by desert mule deer throughout the areas and seasons. Buffelgrass was not important in diets of desert mule deer. Conversely, buffelgrass was the most important forage species for cattle. Also, two of the most important browse species (i.e., mesquite [Prosopis juliflora] and ironwood [Olneya tesota]) for mule deer were the most important browse species for cattle. Desert mule deer and cattle shared 45 forage species from central Sonora. However, biological overlap of diets occurred only for spring (Morisita coefficient = 0.67). Plant diversity in diets of mule deer was slightly different among areas and seasons. The Shannon-Wiener (H') index was different only between the area with higher precipitation and the area with lowest precipitation. Our data contribute to understanding the primary resources for desert mule deer in altered habitats of the Lower Sonoran Desert.