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Zanzibar’s red colobus monkeys much more numerous than thought

  • The team logged 4,725 hours over 2 years tracking down more than 4,000 individual Zanzibar red colobus monkeys (Piliocolobus kirkii).
  • Protected areas house nearly 70 percent of the monkeys they found, where monkey groups tended to be larger and to have more females than those outside of parks and reserves.
  • The team also found that a relatively small number of young monkeys survive to adulthood, and they concluded that the overall population might be declining.

Zanzibar is home to many more individuals of an endemic monkey species than biologists previously believed, according to a recent study.

“Scientists have known about the Zanzibar red colobus monkey for 150 years, yet this is the first systematic study of this poorly understood species across its entire range,” said biologist Tim Davenport in a statement. Davenport directs the Wildlife Conservation Society in Tanzania and was the lead author of a paper published on Dec. 7 in the journal Oryx.

The team logged 4,725 hours over two years tracking down more than 4,000 individual Zanzibar red colobus monkeys (Piliocolobus kirkii) — nearly 3 1/2 times more than past estimates. Davenport and his team gathered information on the sizes of the groups, as well as the ages and sexes of the monkeys they found. The IUCN-listed Endangered primate is found only in the islands that make up Zanzibar, a region of Tanzania in the Indian Ocean.

Although the recent survey revealed a larger population of Zanzibar red colobus monkeys than previously estimated, the researchers believe that the species may be declining. Photo ©Tim R.B. Davenport courtesy of WCS.

“The systematic assessment redefines almost everything we know about this amazing animal, and is now guiding effective management strategies for this species,” Davenport said.

Protected areas house nearly 70 percent of the monkeys they found, and the groups tended to be larger and to have more females than those outside these parks and reserves.

“The results indicate that P. kirkii is resilient and thriving far better than assumed,” the authors wrote.

However, deforestation rates on the island are high, topping 19 square kilometers (7.3 square miles) a year as the number of people living in Zanzibar grows and with it the need for more room for housing and farming. That expansion increases the chances that tree-dwellers like Zanzibar red colobus monkeys might steal crops or that hunters could go after them.

Infographic by WCS-Tanzania.

The team also found that a relatively small number of young monkeys survive to adulthood, leading to the conclusion that, despite the higher-than-estimated total numbers observed, the overall population might be declining. What’s more, the researchers weren’t able to find any monkeys in four spots where they’d once been.

As a result, Davenport and his colleagues recommend the creation of a new reserve to protect the species. They also said the monkeys could be a draw for tourists.

“The Zanzibar red colobus monkey is unique to Zanzibar and could be a wonderful example of how conservation efforts can succeed in protecting both wildlife and habitat, which in turn benefits communities,” Davenport said.

The study also revealed that only a small number of young monkeys survive to adulthood. Photo ©Tim R.B. Davenport courtesy of WCS.

They also advocate shining an even brighter spotlight on the animal by designating it as the national animal of Zanzibar, which maintains a degree of autonomy from Tanzania.

“The species could serve as a fitting symbol for both Zanzibar and the government’s foresight in wildlife management,” Davenport said.

CITATION
Davenport, T. R., Fakih, S. A., Kimiti, S. P., Kleine, L. U., Foley, L. S., & De Luca, D. W. (2017). Zanzibar’s endemic red colobus Piliocolobus kirkii: first systematic and total assessment of population, demography and distribution. Oryx, 1-9.

Banner image of a Zanzibar red colobus monkey ©Tim R.B. Davenport courtesy of WCS.

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