Response of Desert Mule Deer to Habitat Alterations in the Lower Sonoran Desert

by Alcala Galvan, Carlos Hugo.

About 1,600,000 ha of desert mule deer range in Mexico are currently altered with vegetation clear-cutting and establishment of buffelgrass pastures. Consequently, the availability of important resources as cover and forage from scrub vegetation has been reduced for desert mule deer. No previous research has been conducted to investigate how desert mule deer respond to those alterations. Therefore, the purpose of this research was to examine movements of desert mule deer, evaluate their home range sizes and determine habitat use, and analyze their diets in areas of central and western Sonora, Mexico. The approach involved the use of radiotelemetry techniques and GIS programs to calculate home range sizes, examine selection of vegetation associations, and identify the specific components of habitat that better distinguished the characteristics of selected sites by desert mule deer. I used the microhistological technique to determine botanical components of desert mule deer diets, and compare diets of desert mule deer and cattle in habitat with buffelgrass pastures. Diet analyses included spatial and temporal comparisons of diversity and similarity indices. Sizes of home ranges were larger in the more arid environments of western Sonora (27.3 km 2) than in central Sonora (14.5 km2). Desert mule deer used altered habitat differently than use areas without buffelgrass, however, there was no difference in the size of home ranges of mule deer from inside buffelgrass areas and the size of home ranges of deer in native scrub vegetation. Thermal cover, ground cover, and percent of gravel in the ground were the variables that distinguished locations selected by desert mule deer. Desert mule deer selected xeroriparian vegetation and sites closer to water sources. Water sources may have 8 influenced mule deer to stay in buffelgrass areas despite the lack of cover and forage from shrubs and trees. For diets of mule deer, I identified 96 plant species, 69 of which have not previously been reported as forage for this wild herbivore. Desert mule deer and cattle shared 45 forage species from central Sonora. However, biological overlap of diets occurred only for spring. Results from these studies provide information to understand ecological relationships of desert mule deer on altered habitats. 9