Keywords
Age of Mortality
Natural Mortality
Trophy Harvest Age
Trophy Harvest Effect.
How to Cite
Abstract
To assess the influence of trophy hunting on Mongolian Argali Ovis ammon, we compared the ages of trophy rams (n=64) taken through Mongolia’s legal hunting programme with those of mature rams that died of natural causes (n=116). A two-sample Kolomogorov-Smimov test indicated that the distributions of the two groups were different (P-0.001). A two-sample t-test indicated the distributional differences were due, at least in part, to differences in the mean ages between the natural deaths and hunter harvested samples (P=0.001); the distributions were not centered at the same value or the means in the two populations differ. Application of the Central Limit Theorem affirms that the distribution of the sample mean ages for natural death and hunter harvested populations will be approximately normal, making the t-test applicable. The mean age for the natural death sample was 8.7 years (range: 7.0-13.0) compared to 9.4 (range: 7.0-13) for the hunter harvested sample. At the 95% confidence level, the true difference in ages between the trophy kills and natural deaths is between 3 months and 1 year. Since on an average, rams killed by hunters are older than the average age of natural death for mature rams, the legal hunting programme is having little effect on ram age structure. Thirteen years may represent the upper limit of lifespan for wild Mongolian Argali, which is slightly shorter than the life span of North American wild sheep, namely Thinhom Sheep Ovis dalli and Bighorn Sheep Ovis canadensis.References
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