Preliminary study on breeding periodicity of wild francois' langurs (Trachypithecus francoisi francoisi)in Mayanghe Nature Reserve,Guizhou
Francois’ langur, the Black-headed leaf monkey (
Trachypithecus francoisi francoisi), is a rare species of monkey, occurring in isolated small groups in China. Breeding periodicity of wild Francois’ langur in Mayanghe National Nature Reserve in Yanhe County, Guizhou, China, was studied. For the subject group,known as Gandong group, they were artificial fed periodically due to shortage of natural food since August,1997. From the latter half of the year of 1998,they were adapted to artificial feeding and fed once per day. Because of the same feeder, a trust relationship between the group and the feeder was established, and the group could be observed within fifteen meters. Through artificial feeding, Gandong group monkeys were individual recognized according to characteristics of stature, posture and appearance, and the females were differentiated by the way of F1,F2,…. The first dates of seeing newborn monkeys of the group were recorded and regarded as birth dates. The error was not beyond twenty-four hours because of daily observation and record. Birth dates of eleven newborn monkeys of Gandong group from 1999 to 2005 were recorded. The genders of the newborn monkeys were identified by observing male genitals fifteen days after born. In addition, birth dates of six other groups were combined with that of Gandong group. The six groups included Xiangguba group, Leijia group, Banqiaozi group, Shibanxi group, Dashandong group and Longdongtang group. For the six groups, the first dates of finding new baby monkeys were recorded by patrolmen who patrolled once every five days, and then verified by the authors within two days. According to characteristic of baby monkey whose hair was bright orange at first and then became gradually black one month later, birth dates of nine baby monkeys of these six groups were estimated from 2003 to 2004. The error was not beyond one week. By record, eight offspring were added into Gandong group from 1999 to 2005. At present, this group was consisted of seven males and five females, including three baby monkeys and nine non-baby monkeys. Six other groups produced nine offspring totally from 2003 to 2004. The analysis results showed that seasonal birth of wild Francois’langur distributed from January to June, and no newborns were given birth from July to December, seventeen monkeys born from February to April in proportion with 85% in total, eight in March in proportion with 40% determined as the peak of whole year, five in April and four in February as the secondary birth peak. This distribution pattern was different significantly from that of captive Francois' langurs whose birth failed in seasonality. Under captive conditions, food sources were secure, the surrounding was stable and there was little change of annual cycle. However it was difficult for the wild to have the above all conditions. The breeding interval of wild Francois' langurs was 704±50 days averagely, namely twenty-three months, longer seven months than that of captive. Francois' langurs, indicating that natural environmental stresses that the wild populations were subject to might have a long-term influence on reproduction of Francois' langurs. Meanwhile breeding periodicity was linked with difference of species, climate, habitat, and female reproductive biology.
Related Articles |