Thesis

The social ethology of mule deer (Odocoileus hemionus) in Southern California

The social behavior and organization of mule deer (Odocoileus hemionus californicus) were studied from 15 Feb 1977 through 12 Feb 1978 in the Chatsworth Reservoir, Los Angeles, California. Results are based on over 733 person-hours of observation. Seasonal changes in social organization were observed and correlated with ecological and behavioral factors. Does were commonly alone during the fawning season (May-June) when they showed high levels of intolerance toward conspecifics. At all other times of the year females associated in doe or mixed groups of 3-30 individuals. Males were frequently observed in buck groups of' 3-5 or in larger mixed groups. During the rut (October-November), bucks usually traveled singly among doe groups. Multi-male breeding associations resulted. Females commonly led walking patterns, whereas males usually occupied the omega position. No specific individual(s) acted as constant group leader, nor was dominance rank correlated with leadership. High ranking males most often led trotting patterns that had resulted from some source of alarm. Dominance hierarchies among males and among females were maintained the year around through continual agonistic interactions. Adult males were always dominant to females. Maternal does rose in social status during the fawning season but previous dominance relationships were re-established after their fawns disappeared. Changes in social rank between males occurred prior to the breeding season and again after antlers were shed. (See more in text.)

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