Seasonal range use, aerial survey observability and survivorship of male elk (Cervus elaphus manitobensis) in southwestern Manitoba

Abstract

The cause of the low male to antlerless elk ratios observed during winter aerial surveys of an elk population in southwestern Manitoba were investigated. Eleven radio-transmittered male elk provided insight into seasonal range use, movements and activity, dispersal and survival of males in the Spruce Woods population. An evaluation of observability bias between male and antlerless elk during the surveys were also analyzed, as well as sex bias in the harvests of Indians and poachers. Though male elk generally were observed during the winter surveys in smaller groups than antlerless elk, a significant number of males were not missed by observers. When surveys were undertaken during good survey conditions all radio-transmittered male elk were sighted. Radio-transmittered male elk had large spring and fall ranges and smaller summer and wjnter ranges. Generally, immature males had larger seasonal ranges and were less likely to reuse established seasonal ranges than mature males. Immature male elk had greater distances between relocations and activity centers and undertook dispersal movements which increased their vulnerability to mortality factors. The survivorship of radio-transmittered males was low. Elk which inhabited the east side of the Spruce Woods park had higher mortality than elk which inhabited the military reserve. The elk harvests in the study area by poachers and Indians were bias favoring males. The low numbers of males was not an artifact of the survey method but attributed to differential natural mortality, dispersal of immature males and male bias Indian and poaching harvests.