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Boutourlini’s blue monkey groups preferred undisturbed coffee forest and avoided open canopy

Blue monkey sitting among branches in a forest canopy
Research · Ecology

Two groups of Boutourlini’s blue monkey (Cercopithecus mitis boutourlinii) living under very different levels of human disturbance in an Ethiopian coffee forest showed the same strong habitat preference: both selected undisturbed natural coffee forest and avoided open-canopy areas within their ranges.

Researchers followed the two groups for 15 months, from November 2016 to January 2018, in Hamuma Coffee Forest in western Ethiopia. One group, known as the Low Disturbance group, contained 55–58 individuals and spent most of its time in undisturbed natural forest and lightly modified shade-coffee forest. The High Disturbance group contained 32–35 individuals and lived mainly among heavily modified open-canopy coffee forest and shade-coffee forest.

The groups differed more in social activity and range size than in daily activity

Despite this contrast in the habitats available to them, the analysis did not support clear group differences in feeding, travelling or resting. Social activity was clearly higher in the Low Disturbance group. The authors suggest that its larger group size, and therefore greater number of potential social partners, may have contributed to this difference.

Ranging patterns showed a clearer contrast. The High Disturbance group used a larger home range and a larger core area, whereas the Low Disturbance group concentrated its use within a smaller area. However, the analysis did not support a clear difference in daily travel distance, either across the year or between seasons.

Both groups still preferred undisturbed coffee forest

Habitat-selection analyses produced one of the study’s strongest shared patterns. Both groups strongly preferred undisturbed coffee forest when it was available — meaning they used it more than expected from its availability within their ranges — and avoided open-canopy habitat. The result shows that the monkeys continued to favour more intact forest structure even when one group lived in a landscape where disturbed coffee habitat made up much more of its surroundings.

The researchers describe this as evidence that Boutourlini’s blue monkeys can use a range of coffee-forest habitats and show considerable ecological flexibility. At the same time, they do not treat the two groups as a replicated test of disturbance. Only one group represented each disturbance level, and the groups also differed substantially in size. The authors therefore call for studies of more independent groups before drawing firmer conclusions about how habitat modification changes the subspecies’ behaviour and ranging ecology.

Boutourlini’s blue monkey is a threatened primate of western Ethiopia and southeastern South Sudan whose forest range is increasingly affected by agriculture and plantation development. The authors suggest that its ability to persist in modified coffee forests may help populations cope with landscape change, while the consistent preference for undisturbed forest highlights the continuing importance of retaining less-modified forest within these mosaics.

Sources and image credit

  1. Chane, M., Bekele, A., Fashing, P. J., Chapman, C. A., Yazezew, D., Ibrahim, H., Moges, A., Nguyen, N., Eppley, T. M., Venkataraman, V. V., & Mekonnen, A. (2026). Activity, Ranging, and Habitat Use Patterns of Two Groups of Boutourline’s Blue Monkeys (Cercopithecus mitis boutourlinii) in Habitats with Different Levels of Anthropogenic Modification in Hamuma Coffee Forest, Ethiopia. International Journal of Primatology. https://doi.org/10.1007/s10764-026-00574-xPrimary peer-reviewed study, published 30 July 2026

Image: Congo Tourism Gate — blue monkey (Cercopithecus mitis) in a tree near Virunga National Park, Democratic Republic of the Congo; representative forest-habitat image, not from Hamuma or the Boutourlini subspecies. Source: Wikimedia Commons. · CC BY-SA 4.0 · Source

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