Ecology of Vervet Monkeys (Cercopithecus Aethiops) in The Masai‐Amboseli Game Reserve, Kenya

Abstract

Aspects of the ecology of vervet monkeys (Ceropithecus aethiops) are described on the basis of a 21 month field study in East Africa. Analysis of home range utilization demonstrated differences between 4 groups. The smallest group distributed its time over a greater area than did the other groups. For 3 of the groups there appeared to be a strong relationship between group size and the amount of optimal habitat defended. The smallest group defended more optimal habitat than expected. However, this same group spent only 60% of its time in this habitat, whereas the other groups all spent more than 95% of their time in it. The smallest group may have avoided the optimal habitat of its territory as an area of frequent intergroup aggression, and as a result utilized a larger and less productive area. Sleeping—tree preferences of groups and individuals are described and discussed. The minimal distance traveled each day by vervet groups varied from 148 to 2,797 yd. In comparing the mean daily distance covered by 2 groups of equal size it was found that one moved significantly further than the other. More trips were made to permanent water holes between 1300 and 1500 hr and during the dry season than at other times. The frequency of group progressions was greatest at 0700 to 1000 and 1600 to 1900 hr. Study of food habits shows that they were opportunistic omnivores. Elephants were the greatest food competitors of the vervets. The monkeys had at least 16 potential predators. Outside of parks and reserves the greatest predator was the European commercial trapper. Ecological characteristics of vervets and their niche separation from baboons are discussed.

The Social Regulation of Population Density and Age-Sex Distribution in the Toque Monkey

“…It is probable that the decrease in food supply caused these demographic changes. STRUHSAKER (1973) reports similar changes in a population of wild Cercopithecus aethiops in response to a decreasing food supply.…”

“…There were no statistically significant correlations between the proportion of any age-sex class and the size of the troop. A preponderance of females among adults is also reported for Papio (DEVORE & HALL, 1965;ALTMANN & ALTMANN, 1970); Cercopithecus (STRUHSAKER, 1967(STRUHSAKER, , 1973; Macaco mulatto (SOUTHWICK etal., 1965;LIND-BURG, 1971); M. radiata (SIMONDS, 1965); Presbytis entellus (JAY, 1965); P. senex (RUDRAN, 1973); and Alouatta (CARPENTER, 1934); and others. DEVORE & WASHBURN (1963) and DEVORE & HALL (1965) attributed the unequal sex ratio in baboons to sexual differences in the rates of maturation, males requiring several more years than females to attain the adult class.…”

Coping with a challenging environment: Effects of seasonal variability and reproductive status on glucocorticoid concentrations of female baboons (Papio cynocephalus)

“…February and March are particularly hot; on average across the 4 years of the present study, for 63% of the days in February and 74% of those in March the weather station T max was at least 34°C, a temperature that is close to baboons' normal core body temperature of 38°C. In some years Amboseli experiences an 'inter-rain' season of lower rainfall during the January through March period (Struhsaker, 1967;Altmann et al, 2002), especially so during drought years. In such years, environmental stressors may resemble to some extent those in October at the end of normal dry season.…”

Movements of vervets ( Cercopithecus aethiops ) and patas monkeys ( Erythrocebus patas ) as estimators of food resource size, density, and distribution

“…These dierences are presumed to be driven by dierences in food distribution and abundance. Although both vervets and patas feed heavily on gums, vervets also feed on fruits, seeds, and in¯orescences, which can often be eaten in large quantities without moving, whereas patas feed more heavily on arthropods, which are often found while moving (Struhsaker 1967;Whitten 1983;Chism and Rowell 1988;Chism and Wood 1994;Isbell, in press). …”