Fighting between two females for a male in the hoolock gibbon

I observed fighting between two adult females for an adult male in a group of hoolock gibbons (Hylobates hoolock)during fieldwork conducted between November 1988 and December 1990 at Lawachara in the West Bhanugach Reserve Forest, Sylhet, Bangladesh. I discuss the history of the episodes and the consequences of fighting.     

Estimation of density of gibbon groups by use of loud songs

The density of gibbon populations may be estimated by listening for the loud duetted songs of monogamous territorial groups. This method requires a correction factor which must be estimated from the frequency of singing of an adequate number of known study groups. The correction factor and its error were estimated for pileated gibbons (Hylobates pileatus) in Khao Soi Dao Wildlife Sanctuary in southeastern Thailand. Among 30 groups studied, 47% sang per day, on average, but the variation between days and the variation in singing frequency between groups were large. Weather conditions, especially windiness, explained some variation in singing. During an area-wide survey of groups in the sanctuary, unexplained variation in singing from day to day accounted for approximately half of the sample error of group density estimated from 1-day listening samples. Error due to day-to-day variability can be reduced by listening for more than one day at each site. Correction factors based on the cumulative proportion of groups heard during longer (2–5-day) sample periods of listening were closer to 1.0, therefore leaving less room for error and bias of the correction factor. © 1993 Wiley-Liss, Inc.     

Monitoring occurrence,extinction, and colonization probabilities for gibbon populations

All gibbon species (Family: Hylobatidae) are considered threatened with extinction and recognized on the International Union for Conservation of Nature Red List of Threatened Species. Because gibbons are one of the most threatened families of primates, monitoring their status is now critically important. Long-term monitoring programs applying occupancy approaches, in addition to assessing occurrence probability, improves understanding of other population parameters such as site extinction or colonization probabilities, which elucidate temporal and spatial changes and are therefore important for guiding conservation efforts. In this study, we used multiple season occupancy models to monitor occurrence, extinction, and colonization probabilities for northern yellow-cheeked crested gibbon Nomascus annamensis in three adjacent protected areas in the Central Annamites mountain range, Vietnam. We collected data at 30 listening posts in 2012, 2014, and 2016 using the auditory point count method. Occurrence probabilities were highest in 2012 (0.74, confidence interval [CI]: 0.56–0.87) but slightly lower in 2014 (0.66, CI: 0.51–0.79) and 2016 (0.67, CI: 0.49–0.81). Extinction probabilities during the 2012–2014 and 2014–2016 intervals were 0.26 (0.14–0.44) and 0.25 (0.12–0.44), respectively. Colonization probabilities during 2012–2014 were 0.44 (0.19–0.73) and between 2014 and 2016 was 0.51 (0.26–0.75). Although local site extinctions have occurred, high recolonization probability helped to replenish the unoccupied sites and kept the occurrence probability stable. Long-term monitoring programs which use occurrence probability alone might not fully reveal the true dynamics of gibbon populations. We strongly recommend including multiple season occupancy models to monitor occurrence, extinction, and colonization probabilities in long-term gibbon monitoring programs.     

洞庭湖流域麋鹿等哺乳动物濒危灭绝原因的分析及其对麋鹿重引入的启示

洞庭湖流域曾有亚洲象(Elephasmaximus)、犀(Rhinocerossp.)、麋鹿(Elaphurusdavidianus)、川金丝猴(Rhinopithecusroxellana)、长臂猿(Hylobatessp.)、大熊猫(Ailuropodamelanoleuca)、梅花鹿(Cervusnippon)、棕熊(Ursusarctos)等哺乳动物分布,但受古气候、古地理以及人类活动的影响,这些哺乳动物已在洞庭湖流域灭绝。这些哺乳动物的濒危和灭绝既受自然环境变化和灾变的影响,也与物种本身生物学特性和人类活动有关,尤其与人类捕杀和生境丧失有关。据古籍记载分析:在洞庭湖流域,亚洲象和犀于北宋末期灭绝或已南迁,而野生麋鹿、大熊猫、川金丝猴、长臂猿、梅花鹿和棕熊等于19世纪末灭绝。根据我们对30个自然保护区或森林公园野生动物资源实地调查的结果,在洞庭湖流域已记录到21种国家重点保护哺乳动物,其中有5、6、10种哺乳动物分别处于“极危”、“濒危”、“易危”等级,这表明物种濒危的过程仍在继续。导致这些现生哺乳动物濒危的主要原因是生境丧失、人类猎捕、环境污染等,而人类活动干扰对现生濒危物种存活的影响越来越大。洞庭湖流域重引入麋鹿需采取人类协助生存策略:提供足够的且受洪水影响小的适宜生境、保证稳定的奠基者种群数量、减少人为干扰、调控种群密度、实施社区共管和生计替代项目、加强疾病防治、完善保护措施、加大保护基金投入、加强生境监测和湿地恢复等。     

东黑冠长臂猿鸣叫特征及气象因子对鸣叫的影响

鸣叫是长臂猿非常典型的一个特征,并且受到生物因素和非生物因素(如气象因子) 的影响。为了解东黑冠长臂猿的鸣叫特征以及气象因子对鸣叫的影响,2008 年8 月至2009 年10 月,采用全事件记录法对栖息在广西邦亮自然保护区3 个东黑冠长臂猿野生群体的鸣叫行为进行观察。结果表明东黑冠长臂猿倾向于在早晨鸣叫,有91.4% 的鸣叫发生在日出前0.5 h 至日出后3 h 之间,其中53.1% 的鸣叫发生在日出后1 h 内。平均每个群体的鸣叫频次为69.7% ,一个群体平均每天鸣叫1.24 次,鸣叫的平均持续时间为18.3 min。一次二重唱中,雌性平均激动鸣叫4.4 次。长臂猿鸣叫的起始时间在光照强度的影响下差异显著,阴天和雾天鸣叫的起始时间延后,且雾天最迟;降雨致使长臂猿体能的损失和光照强度减弱,从而引起鸣叫起始时间的延后和持续时间缩短;温度对长臂猿鸣叫的影响并不显著。     

西黑冠长臂猿雄性取代前后鸣叫行为的变化

本文通过长时间的野外监测,首次报道了西黑冠长臂猿的一次雄性取代行为。一个研究群体(G3)中的1 只亚成年雄性长臂猿在10 岁左右取代了相邻群体(G2)中的成年雄性。整个取代过程持续了15 d时间。雄性取代发生前,G2 中雌雄的配对关系已经不稳固,这为雄性取代提供了机会。而G2 与G3 群的一次长时间冲突可能消耗了G2 中成年雄性大量体能,这为G3 中的亚成年雄性打败并取代G2 中的成年雄性创造了机会。本研究在取代发生后,对新形成群体的鸣叫行为进行了连续4 个月的监测。结果表明与处于稳定时期的G2 群相比,新形成群体的鸣叫频次更高,但每次二重唱中雌性的平均激动鸣叫次数降低。这证明了Geissmann (1986)提出的假说,新配对的群体应该在尽量短的时间内多练习二重唱,这样导致新配对群体的鸣叫频率明显升高。虽然经历了4 个月的合唱练习,新形成群体的激动鸣叫次数仍然偏低,并且两只雌性同时激动鸣叫的频次也比较低。这说明新形成的配对之间配合依然不默契,或者说明配对之间的关系还不稳定。     

Is gibbon ape leukaemia virus still a threat?

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Singing behavior and singing functions of black‐crested gibbons (Nomascus concolor jingdongensis) at Mt. Wuliang,central Yunnan,China

We used data on loud duetted and solo songs collected from one habituated polygynous group of black‐crested gibbons (Nomascus concolor jingdongensis) on Mt. Wuliang, Yunnan, to test several hypotheses about the functions of these songs. The major functions proposed for loud gibbon songs include resource defense, mate defense, pairbonding, group cohesion and mate attraction. Duet bouts are generally initiated by adult males, who select the highest trees near to ridges or on steep slopes as singing trees. Such trees facilitate voice transmission and inter‐group communication. Singing trees tended to be located near important food patches and sleeping sites, which supports the resource defense hypothesis. The adult male and two adult females always sang interactively, alternating male phrases with the females' stereotyped great calls, to produce the duets, and females rarely produced great calls if they were more than 30 m from the male. The two females usually produced great calls synchronously during the duet, especially when they were close together. These features support both the mate defense and pairbonding hypotheses. The number of great calls and their degree of synchrony transmit information about spatial relationships and possibly pairbond strength to members to neighboring groups and floating animals. During or after the duet bouts, the adult females and juvenile moved toward to the adult male; and group members maintained a close spatial relationship, which supports the group cohesion hypothesis. Other incidents observed suggest a mate competition role for duets. The adult male always sang when the females started duetting with the subadult male. The subadult male sang solo bouts, but they were not more frequent or longer than bouts initiated by the adult male. Although mate attraction is the likely function of subadult solos, it was not convincingly demonstrated. In conclusion, all hypotheses concerning the function of singing are supported by at least some of the data, and none can be excluded. Am. J. Primatol. 71:539–547, 2009. © 2009 Wiley‐Liss, Inc.     

Prevalence, whole genome characterization and phylogenetic analysis of hepatitis B virus in captive orangutan and gibbon

Background Hepatitis B virus (HBV) is a public health problem worldwide and apart from infecting humans, HBV has been found in non‐human primates. Methods We subjected 93 non‐human primates comprising 12 species to ELISA screening for the serological markers HBsAg, antiHBs and antiHBc. Subsequently, we detected HBV DNA, sequenced the whole HBV genome and performed phylogenetic analysis. Results HBV infection was detected in gibbon (4/15) and orangutan (7/53). HBV DNA isolates from two gibbons and seven orangutans were chosen for complete genome amplification. We aligned the Pre‐S/S, Pre‐C/C and entire genomes with HBV sequences and performed phylogenetic analysis. The gibbon and orangutan viruses clustered within their respective groups. Conclusions Both geographic location and host species influence which HBV variants are found in gibbons and orangutans. Hence, HBV transmission between humans and non‐human primates might be a distinct possibility and additional studies will be required to further investigate this potential risk.     

Infant care in a family of siamangs (Hylobates syndactylus) with twin offspring at Berlin Zoo

Infant-carrying in a family group of siamangs with twin offspring was observed during a 2-week period. The twins were about 11 months old at the time of the study. One or both twins were usually carried by their father, but hardly ever by their mother. A considerable amount of infant-carrying was also contributed by the twins' juvenile brother. Helping behavior (defined as the care of offspring by individuals who are not their parents) is not normally known to occur in siamangs or other hylobatids. We suggest that the presence of multiple offspring may have facilitated the occurrence of infant-carrying exhibited by a nonparental family member. This finding may point to one of the mechanisms influencing the occurrence of helping behavior in general.