Population Size and Behavioral Ecology of Bale Monkey (Chlorocebus Djamdjamensis) in Human-Dominated Landscapes of Sidama Highlands, Southern Ethiopia
No Thumbnail Available
Date
2020-05-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Bale monkeys (Chlorocebus djamdjamensis) are endemic, bamboo specialists, restricted to a narrow geographic range in the Ethiopian highlands currently recognized as vulenerable speceis by IUCN. The study was conducted to investigate the impacts of habitat loss and fragmentation on behavioral ecology and population size by comparing two groups of Bale monkeys in relatively continuous Garamba Forest and fragmented Afursa Forest in human-dominated Sidama highlands. Phenological pattern was assessed within each group’s home range to investigate the overall vegetation composition and temporal changes in food availability. Phenological data was analyzed from eight plant species: five trees, two shrubs and one bamboo. Total count method was used to estimate the population size of Bale monkeys. Data on activity budget, feeding ecology, and ranging ecology of the two groups of Bale monkeys were quantified using scan sampling method. Ranging ecology data were analyzed using a combination of ArcGIS and Home Range Tools. Plant species with DBH ≥ 10 cm in the range of Garamba Forest group (G) had higher stem density (768 stems/ha) than Afursa Forest (A) (624 stems/ha). Plant species diversity and evenness were lower and dominance was higher in Garamba Forest than in Afursa Forest. There were statistical differences in food availability indices of young leaves (P<0.05) and matured leaves (P <0.05) between the two Bale monkey groups across months. The total population size of Bale monkeys was 225 individuals. The average group size was 20.5 at Worbadula, 25.5 at Afursa and 33.25 at Garamba. Group-A spent significantly less time feeding (54.1% vs 57.3%, moving (19% vs 22.1%) and significantly more time on resting (17.2% vs 13.2%), socializing (8.69% vs 5.1%) than Group-G. More plant species (32) were identified as food source for Group-A than species in Group-G (14). Food item consumption markedly varied between groups (P<0.05), Group-G spent more time feeding on bamboo young leaves (51.02% vs 0%), bamboo young shoots (12.15% vs 0%) and significantly less time feeding on non-bamboo young leaves (3.43% vs 36.69%), fruits (12.9% vs 22.53%), stems (4.25% vs 19.63%) and insects (3.8% vs 12.35%). The time spent feeding on different growth forms of plant species by two groups of Bale monkeys also varied, Group- G spent more time feeding on bamboo (63.49% vs. 0%) while Group-A spend more time feeding on trees (27.98% vs 24.67%), graminoids (19.6% vs 1.94%), shrubs (19.28% vs 4.87%) and forbs (17.34% vs 1.23%). Bale monkeys in Garamba Forest had higher movement rate (m/hr) than in Afursa Forest group. Bale monkeys are highly threatened due to habitat loss and fragmentation and adapted anthropogenic alteration by adjusting ecological flexibility with respect to habitat type. Conservation managers should do more to ensure the long-term survival of this unique, little known, endemic and endangered species.
Description
Keywords
Bale Monkey, Feeding Flexibility, Fragmentation, Population Status, Sidama