| 其他摘要 | The ecology and behavior of black crested gibbon (Nomascus concolor jingdongensis) was studied from March 2003 to April 2006 at Dazhaizi (24°21′N, 100°42′E) Wuliang Mountain, central Yunnan, China. The singing behavior of 3 groups (G1, G2, and G3) was monitored from March 2003 to March 2004. One group was finally habituated in March 2005. From then on, ecological and behavioral observations were conducted for 14 months (until April 2006) and obtain a total of 845 contact hours. So a quantity of ecological and behavioral data on diet, time budget, ranging behavior, habitat use, sleeping trees and sleep-related behavior was collected. In addition, the data on population size, mating system, birth intervals, death rate, carrying capacity and cases of catastrophe were also collected to simulate population dynamics of the black crested gibbon at Dazhaizi with the computer program Vortex 9.14. The adults of black crested gibbon exploited the highest frequency range to give out loud morning songs in all gibbons. The two adult females in each group could produce great calls synchronously. The black crested gibbons sang on average 53% of days monitored, and 1.09 duet bouts per singing day. 91.5% of the duets were produced between half an hour before and three hours after the sunrise. The average duration of the duets was 12.9 minutes, and females produced 4.6 great calls in each duet bout, the intervals between two successive great calls were generally 115 seconds. Starting time, duration of the duets and the number of female great calls did not show significant seasonal variations. There was no significant difference in the duration and frequency of the duet bouts, but there was significant difference in the number of the great calls and intervals between great calls among groups. Neighboring groups did not tend to sing on the same day. Although they sang on the same day, the study groups seldom started duets when the neighbor was singing or within 5 minutes after the singing stopped. The intervals of two groups singing on the same day were similar or significantly longer than intervals between song bouts randomly selected from the two same groups but singing on different days. We concluded that a group’s duet could not elicit its neighbor to duet. The male gibbons tended to select high tree to sing. The individuals decreased distance after the duets which suggested the duet play the group-cohesion function. Data on feeding patterns were collected by scan sampling at 5-min intervals. Gibbons consumed 77 different plants and at least six animals. Buds and leaves constituted 46.5% of the diet. Fruits and figs accounted for 25.5% and 18.6% of the diet respectively; while flowers and other plant parts contributed 9.1% and 0.3%. The gibbons tended to eat more fruits and figs during the first and last hour of the day. There was marked seasonal variation in food choice, and fruits, leaves and flowers were each predominant at different months of a year. Seasonal variation in availability of figs and fruits may be the primary factor in the gibbons’ food selection. The diet of N. C. jingdongensis contains more leaves when compared to the diets of other gibbons with the exception of siamangs. To ensure the continued survival of the population, the annual important food resources and the main food species in each month must be protected. On average, the group left sleeping trees 33 min. after sunrise and retreated back sleeping sites 128 min. before sunset. The gibbons spent 40.0% of the time resting, 28.7% feeding, 19.8% traveling, 6.1% foraging, 2.6% singing, and 2.8% in other activities. During the course of the day, feeding and foraging manifested a bimodal pattern of high activity levels in the middle morning and the middle afternoon, while resting reached a peak in the midday, with proportionally less time used for traveling. The proportion of time allocated to activities showed significant seasonal variations. The gibbons increased traveling and playing time and decreased feeding time when they ate more fruit, on the contrary, they spent less time in traveling and playing time and more time in feeding when they ate more leaves. The gibbons reduced their traveling time and increased their resting time when the temperature was low. The group entered 129 1-ha quadrats; however, if the lacunae within the borders of this area in which gibbons were not observed were included, the group’s home range would cover 151 ha. The home range consisted of 3 big valleys. Daily distances travelled varied greatly, averagely 1391 m (range: 300~3144m，SD=703m). It was negatively correlated with the feeding time and the proportion of leaves in the diet, and positively correlated with the proportion of fruit in the diet.The gibbons concentrated 69.7% of their activities in 29 particular quadrats. Besides February 2006, the group always selected primary forest. Food distribution, dietary proportions and topography were the main factors which influenced the ranging behavior of the study group. Individuals preferred specific areas to sleep; all the sleeping sites were situated in primary forest with most of them (77%) between 2,200 - 2,400 m in elevation. Individuals tended to select tall, thick trees with large crowns on steep slopes (mean: 54°, range: 35-80°, SD=11.1°) to spend the night. Few sleeping trees were selected repeatedly by the same or other members of the group. The gibbons entered the sleeping trees 128 minutes before sunset (on average at 17:02 h) and left the sleeping trees 33minutes after sunrise (on average at 7:59 h). The time period between first and last individual entering was average 17.8 min. Members of the group usually formed four units (adult male and juvenile, two adult females with their dependent infants, and the sub-adult male) spread out in different sleeping trees. So the sleep-related behaviors were thought to adapt to minimize the risk of being detected by predators, and the choice of sleeping tree made it difficult to approach and attack for predators and provided an easy route for gibbons to escape in the dark. In addition to avoidance of predation, maintaining warmth was another factor in the selection of sleeping sites for black crested gibbons. Results of the population dynamics of simulation from VORTEX MODEL (ver. 914) suggested that in the absence of poaching the population would reach carrying capacity within the next 100 years. However, a modest harvest of one male and one adult female each year would result in the population going extinct within 78 years. The time to carrying capacity of 100 years is the result of the high mortality rate experienced by this population. Loss of genetic diversity would be greater if the population remained low or well below carrying capacity rather than if allowed to reach carrying capacity. The results suggested that long-term survival, in the absence of poaching, was primarily limited by the carrying capacity of Dazhaizi. Therefore, to protect the population was dependent on the prevention of poaching and a reduction or complete cessation of habitat loss. One important step in reducing habitat loss promoting forest regeneration will be to restrict domestic animals in the habitat of black crested gibbon. In addition it will be crucial to protect and improve corridors connecting this population to surrounding populations. |
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