Effect of Anthropogenic Habitat Modification on Behavioural Ecology of Boutourlini's Blue Monkey (Cercopithecus Mitis Boutourlinii Giglioli, 1887) in Hamuma Coffee Forest, Southwestern Ethiopia
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Date
2020-06-06
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Addis Ababa University
Abstract
Boutourlini's blue monkey (Cercopithecus mitis boutourlinii) is a subspecies of Cercopithecus mitis, endemic to southwestern tropical forest of Ethiopia. The subspecies is highly threatened by destruction of forest habitat for agricultural land and categorized as “Vulnerable” taxon. Understanding the effect of anthropogenic habitat destruction on behavioural ecology of this little known subspecies is crucial to design conservation and management plans. Therefore, the aim of this study was to examine the ecological and behavioural flexibility of Boutourlini's blue monkeys in response to anthropogenic habitat modification by comparing two habituated groups occupying two habitats at different levels of disturbance in Hamuma Coffee Forest. Vegetation surveys were carried out in the home ranges of each group to quantify the overall vegetation composition. A total of 40 10 × 50 m2quadrats along 8 randomly selected transect with 400–600 m long and 10 m wide were used and sampled for the diversity of big trees (DBH ≥ 10 cm) and small trees (≥2 m tall and <10 cm DBH). Phenological data were analyzed from 15 plant species: 11 trees, two shrubs and two climbers. The activity time budget, feeding ecology, ranging, habitat use and positional behaviour were studied in both groups for five minutes with 15 minutes interval scan sampling for 15 months study period. Species name and required characters of domicile trees selected by both groups were recorded for 12 months. Plant species with DBH ≥ 10 cm in the range of Natural coffee forest group (NCF-group) had higher stem density (443 stems/ha) than in Coffee plantation group (CP-group) (334 stems/ha). Plant species diversity was significantly greater in NCF (H'=2.82) than CP (H'= 2.47) (t = 4.57, df = 714.93, P < 0.001). Young leaves were the most abundant plant parts throughout the year and did not show significant difference in the home ranges of both groups (P > 0.05). Ripen fruit availability indices (RFAI) was significantly higher in NCF-group than CP-group across months (Wilcoxon S.R. W=107, P=0.045). The overall mean percentage time spent resting, feeding, moving, socializing, and other activities between two groups were not significantly different (ANOVA: df =1, F = 0.34, P > 0.05). Boutourlini's blue monkeys were observed feeding on 37 plant species belonging to 27 families. Mean proportion of feeding on young leaves and ripen fruits was significantly higher than, matured leaves, flowers and buds (P < 0.05) in both groups. The top 10 species comprised over 70% of the overall diet of Boutourlini’s blue monkeys. Daily path length and movement rates did not show significant variation between the two groups. A 50% Kernel density estimate (KDE) was the core area utilized more frequently by the groups and a bit smaller in NCF-group (7.22 ha) than in CP-group (12.52 ha). Slight differences were seen in their positional behavioural repertoire, while domicile tree selection showed more profound differences between the two groups. Compared to other microhabitats, both groups spent more time in tree dominant forest more than expected. The results demonstrate that Boutourlini's blue monkey showed a tendency in ecological and behavioural flexibility in response to anthropogenic habitat modification. However, further and repeated studies are required to determine the threshold of habitat destruction that Boutourlini's blue monkey can cope with.
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Anthropogenic Disturbance, Behavioural Flexibility, Boutourlini's Blue Monkey, Diet, Hamuma Coffee Forest, Ranging, Positioning