生態系と生態学のジャーナル

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Population Status, Group Size, and Threat to Boutourlini?s Blue Monkeys ( Cercopithecus mitis boutourlinii)

Ensermu Kibebew and Kassahun Abie

The present study was conducted to determine population and group size, and identify major conservation challenges to the blue monkey (Cercopithecus mitis boutourlinii) in Jibat forest. Data were collected from July 2012 to April 2013 through direct field observation, focus group discussion, interview, and questionnaire survey. Individual count was used to determine the current population size, seasonal distribution, and sex and age structure of blue monkey. Data were analyzed using descriptive statistics. Chi-square test was used to compare the sex and age ration, and their distribution among the counting blocks. The mean estimated population of Boutourlini’s blue monkeys in the study area was 188 individuals. Of which, adult males and adult females comprised 18.61% and 33.77%, respectively. There was statistical difference between the number of adult males and adult females (χ2=8.495, df=1, p<0.05). The proportion of young and infant groups was 27.12% and 20.47%, respectively. There was no statistical difference among the age categories of blue monkey in the Jibat forest (χ2=11.277, df=3, p>0.05). The sex ratio of adult males to adult females was 1:1.81, and adult female to infant was 1:1.65. Blue monkeys in the study area were seen mostly in groups and occasionally in pairs. The range of troop size varied from 2 to 21 with mean of 11 individuals of various sex and age categories. Major threats for blue monkey recorded in the study area were deforestation, poaching, agricultural land expansion, overgrazing, human encroachment, tree cutting and cultivation. Increasing human population density with the absence of participatory forest management has accelerated deforestation of the natural ecosystem and loss of wildlife.