Range and population expansion as tools to reduce the extinction risk in a 'critically endangered' primate : kipunji Rungwecebus kipunji

Abstract

Kipunji Rungwecebus kipunji, a Tanzanian endemic and Africa's rarest monkey, was only discovered in 2003. It was subsequently categorised as 'critically endangered' on the IUCN Red List, with 93% of the population found in the degraded Mt Rungwe and Livingstone forests (RL) of the Southern Highlands. Aspects of kipunji ecology and habitat characteristics were investigated for the RL population to inform future evidence-based conservation, and more specifically to look at how range and population expansion can be used as tools to reduce the extinction risk of a 'critically endangered' species. Habitat use models developed for kipunji suggested that they are able to tolerate some forest disturbance, such as a fragmented canopy, as long as this is associated with specific tree communities at mid to lower altitudes. Predictions of habitat suitability suggest there is little room for expansion within forests around the known kipunji range (RL extent of occurrence = 42 km"), although the original habitat in areas south of the current range, now deforested, would have been highly suitable. From these results, improving habitat quality and connectivity inside the forest, and reforesting parts of the former range outside of the forest, would be needed to facilitate range expansion. Twenty three kipunji groups were studied to record demographic data testing a partial count method, used as a response to the problems of estimating age-sex ratios for shy, cryptic and arboreal animals. This method demonstrated potential as a quick and simple way to collect baseline population data. Kipunji demographics indicate a 'healthy' population composition (based on current numbers of adult females to males, females with infants, and proportion of infants per group) that is stable, if not increasing. There is no evidence so far to suggest that kipunji group size changes along a gradient of forest disturbance, although some demographic parameters are inversely correlated with forest disturbance and may be linked to resource availability. The 22-month foraging ecology study demonstrated that kipunji have a wide, diverse and predominantly fruit-rich diet. Fruit consumption was correlated with fruit availability which showed a peak during the wet season, and a period of fruit scarcity in the driest months (August-October). During this period, three fallback foods (unripe fruits, mature leaves and pith) were widely consumed. α diversity and evenness of diet was remarkably similar across months, but there was high β diversity in diets across months at the cusp of wet and dry seasons, and during periods of low fruit availability This suggests considerable dietary adaptability to fluctuating resources, which may act to buffer against further forest disturbance. Tree species associated with relatively undisturbed forest were significantly more important in the diet, especially in the dry season, than those of disturbed forests. Regeneration of key trees appeared healthy except in two important Ficus species. Patterns of home range use showed that temporal and spatial patterns were linked to fruit availability. An expansion of the range occurred with low fruit availability in the dry season, and a longer dry season daily path length was associated with an increase in diversity of fruits in the diet. Activity budgets changed between seasons with a greater proportion of time spent feeding in the dry season. Kipunji exhibited long ranging patterns of home range use, rarely returning to the same site on successive days, which probably facilitated resource monitoring and/or allowed dietary switching as fruit scarcity increased during 'leaner' periods. The main pressures on kipunji in the forest are from logging, charcoal production and hunting. Retributive hunting on the forest edge also occurred in response to crop raiding of maize (and to a lesser extent legumes and potatoes) by kipunji and Moloney's white-collared monkey. This was a localised problem in the wet season months (December to April), and was predicted primarily by the presence of maize, and not habitat measures, suggesting that reforestation schemes at the forest boundary might not necessarily increase the incidence of crop raiding. Mitigation measures should include methods that create physical barriers/buffer zones between maize and the forest edge. The matrix habitat adjacent to the RL forests was dominated by agriculture, interspersed with some small forest patches and single trees, which may be useful as 'links' in the landscape. Matrix habitat immediately bordering the forest was very different from forest within the reserve, and this 'hard edge' means that reforestation to create 'extra' kipunji habitat would basically start from nothing. Kipunji habitat creation which seeks to relieve pressure on the forest and directly benefit communities is likely to be supported as 95% of villagers interviewed were willing to become involved in tree planting/reforestation schemes. Reforesting 800 ha, which may be sufficient for an 'extra' 500 kipunji (almost 50% of the total current population), could cost $491,400 based on current land prices, a relatively modest sum with potentially significant outcomes for a threatened species, but feasibility of such a scheme might be limited by socio-political factors.EThOS - Electronic Theses Online ServiceGBUnited Kingdo