Reliance on Exotic Plants by Two Groups of Threatened Samango Monkeys, Cercopithecus albogularis labiatus, at Their Southern Range Limit
Understanding how threatened species adapt their behavior to landscapes shaped by humans is increasingly important to ensuring they persist in a changing world. Matrix habitats can be shared spaces where human and nonhuman primates coexist. We set out to determine how an endemic, threatened forest specialist, the frugivorous, arboreal samango monkey (Cercopithecus albogularis labiatus), has responded to a matrix habitat made up of residential gardens and commercial plantations in Eastern Cape province, South Africa. We followed two groups from dawn to dusk for a mean of 3 days/mo for 12 mo (February 1, 2011 to January 31, 2012) using scan sampling to collect data on their diet, activity, and ranging patterns. We used resource abundance transects to describe the groups’ home ranges and monitored tree phenology to calculate fruit and seed availability indices. Monkeys from both groups consumed large quantities of exotic plant species, accounting for >50% of their overall annual diet, with seeds of the invasive black wattle (Acacia mearnsii) the most commonly consumed exotic species followed by acorns of two oak species (Quercus robur and Q. palustris.). However, monkeys responded to the availability of indigenous rather than exotic fruits and seeds and increased their consumption of exotics when indigenous fruits were less available. Although monkeys spent less time moving when feeding on exotic species compared to indigenous species, eating exotics did not free up monkeys’ time to rest or socialize, as additional time was required to process exotic foods. To offset the possible negative consequences of the monkeys’ reliance on exotic seeds, including escalating conflict between monkeys and people in gardens, we suggest gradual removal of exotic plant species in the habitat and replacement with indigenous species as one mitigation strategy.
KeywordsAcacia mearnsii Black wattle Cercopithecus mitis Ecological flexibility Fallback foods Human-modified habitat
K. Wimberger thanks Dr. A. Tordiffe, Prof J. O’Riain, and Dr. S. Boyes for tremendous support during and following fieldwork. Thanks to N. Amstrong for help in conducting plant transects and plant identification, where T. Dold and T. Trinder-Smith also helped with the latter. For GIS support thanks to N. Lindenberg and T. Slingsby at the University of Cape Town. Thanks to the Hogsback residents who allowed K. Wimberger access to their properties to follow the monkeys. We thank Hogsback resident T. Webster and South African Weather Service (SAWS) for access and use of their ambient and rainfall data. We thank University of KwaZulu-Natal for the lending of capture cages. Without the support of the following funding sources this project would not have been possible: Claude Leon Foundation, UCT URC Fellowship, JMasters NRF Fund, Novartis SAVF Wildlife Research Fund, Primate Conservation Inc., and Mazda Wildlife Fund. K. Nowak was supported by a Durham University CO-FUND Junior Research Fellowship during the preparation of this article. We thank Shane A. Richards for his valuable advice on analyses. Finally, we thank the guest editors Noemi Spagnoletti, Kimberley Hockings, and Matt McLennan; editor-in-chief Joanna Setchell; and also two anonymous reviewers for their helpful comments on our manuscript.
Compliance with Ethical Standards
Conflicts of interest
The authors have no conflict of interest and no competing financial interests.
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