The Mona Monkeys of Grenada, Sao Tome and Principe: Long-Term Persistence of a Guenon in Permanent Fragments and Implications for the Survival of Forest Primates in Protected Areas

Forest dwelling mona monkeys (Cercopithecus mona) were introduced to the Caribbean island of Grenada and the Gulf of Guinea islands of São Tomé and Príncipe 200–500 years ago and have remained isolated from their African mainland conspecifics for at least 200 years. All three island populations provide insight into the possible medium-term future of small populations of African forest guenons isolated in forest fragments due to deforestation and human hunting. The forest habitats on the three islands range in size from 5,000 to 25,000 ha. Genetic studies indicate that the Grenada population originated from potentially a single female and is a subset of the São Tomé population, which had a larger founding size. The Grenada population now numbers in the thousands, as do the populations on São Tomé and Príncipe. The Grenada monas appear to have suffered no inbreeding effects and may be an example of genetic purging, the process where deleterious phenotypes are weeded out of very small populations if they are allowed to rapidly rebound. Monas are ecological generalists and thus may have been conferred additional survival benefits on each island by their ability to take advantage of completely novel forest habitats. The Grenada monas, in particular, demonstrate that it may not be a lost cause to conserve very small populations of forest primate species in habitat fragments, if they can be immediately protected from further depredation and if the species has some ecological flexibility.