Bark-stripping and food habits of blue monkeys in a forest plantation on mount Meru, Tanzania

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Sokoine University of Agriculture


Bark-stripping of Cupressus lusitanica (cypress) and Pinus patula (pine) by blue monkeys (Cercopethicus mitis kibonotensis) in Meru Forest Plantations has been a problem since they were established in the early 1950s. This study was conducted in 1987 in the Sokoine University of Agriculture Training Forest, a portion of the Meru Forest Plantations, to determine the magnitude of bark-stripping in relation to the food habits of blue monkeys. The extent, intensity and effects of bark damage were assessed in compartments with trees 3 to 14 years old, and the pattern of debarking was monitored throughout the year. On the average, 79.5 % cypress and 88.7% pine trees were debarked. Blue monkeys preferred dominant cypress trees to intermediate trees. In contrast, intermediate pine trees were more damaged than dominant trees. trees were least damaged. In both species, suppressed In all types of trees, the most severe bark damage occurred at the middle and top of the tree trunks. Twisted bole was the most common defect developed by damaged trees; 34% cypress and 38% pine trees were twisted at the middle and top sections. Bark-stripping was low in the rain season and increased in the dry season peaking at 22% of trees damaged in June and July. • The food habits data were collected from the indigenous forest at two sites within the plantation. plant species were eaten by blue monkeys. A total of 38 Fruits were theiv most frequently consumed food item and averaged 76% of the monthly feeding records. Leaves were the next important food item but they were inversely related to the feeding on fruits. The other food items (flowers, shoots, petioles and bark) were similarly inversely related to the feeding on fruits. Bark­ stripping was negatively correlated to the feeding on fruits, and thus increased when the feeding on fruits declined. Fruits of Ficus thonninqii were the prime item in the diet of blue monkeys contributing 50 to 60% of the monthly feeding records. The amount of fruit on these trees in the area was also inversely related to extent of bark damage in the plantation. The water and carbohydrate in the bark of cypress and pine trees was determined to examine if they influenced the bark-stripping. These were poorly correlated to the monthly debarking of both tree species.


PhD Dissertation


Blue monkeys, Forest plantation, Mount Meru, Bark-stripping, Food habits-blue monkeys, Tanzania