Abstract
Bates’s Pygmy Antelope Neotragus batesi was studied for 15 consecutive months in North East Gabon. Fourteen animals were individually marked and six of them (5 ♀ ♀ and 1 ♂) monitored by radio-tracking. During the same period, 128 specimens were collected outside the study area, to examine the stages of growth of their jugal teeth, tooth wear and reproductive condition. Four age-categories can be recognized among young animals, and five among adults. In the mature rain forest Neotragus batesi is commonly found in tree falls and along riversides. It thrives in secondary growth vegetation and native plantations where it reaches its highest population densities. Both its morphology and habits are well adapted to locomotion through dense undergrowth. Bates’s Pigmy Antelope is active by day as well as by night, with peaks in the morning and the evening. It rests in the middle of the day, and in the beginning and middle of the night. The home ranges are small (1 to 3 ha for females ; 2 to 4 ha for males). This area is not used evenly throughout the year ; the core-area of the range changes in keeping with the seasons. Furthermore, every home range includes areas which are used only by day and others which are visited only by night, vegetation structure differing accordingly. The more regularly tended native plantations are those which produce the most food for Neotragus batesi, but periodical clearing of the undergrowth also disturbs the animals. Bates’s Pygmy Antelope has therefore to make use of both well managed native plantations and neglected ones or secondary growth to ensure its food supply and shelter. About 200 species of plants are eaten by Neotragus batesi in N.E. Gabon. Usually this pigmy antelope makes use of a given area when its plant food is most readily available, thus quickly adapting to new situations. Some of the most actively sought plant species, however, may definitely be scarce. On the whole this animal tends to browse upon the most nutritious parts of the plants it selects. Bates’s Pigmy Antelope is a solitary animal ; 76 % of the individuals encountered were alone. More than one female can share a single home range, whereas males never do so. Interindividual communication is mostly achieved through short groans (between a young animal and its mother, or between adult males and females), and through olfactory marking by the secretion of males’ anteorbital glands. Females do not display any territorial behaviour, whereas males might do so. Males are apparently polygamous, their large home ranges overlapping those of several females. Females give birth throughout the year, with peaks at the end of each of the two rainy seasons. In this way the young animals are weaned at a time when fresh grass is readily available. Mortality rate among males apparently increases at the M² stage, when the young leave their mothers’ ranges, and also among the oldest adults. Among females mortality seems to be the highest amongst subadults, at the onset of the reproductive period. Females, as usual, outlive males. Competition with sympatric ungulates is avoided by differences in size, a protracted activity rythm, and a strictly folivorous diet.
Published Version
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