四川动物  2016, Vol. 35 Issue (4): 632-637

扩展功能

文章信息

韦周全, 陆施毅, 赵霏, 李友邦
WEI Zhouquan, LU Shiyi, ZHAO Fei, LI Youbang
亚洲叶猴社会行为学研究进展
Process in the Study on Social Behavior of Asian Leaf Monkeys
四川动物, 2016, 35(4): 632-637
Sichuan Journal of Zoology, 2016, 35(4): 632-637
10.11984/j.issn.1000-7083.20160012

文章历史

收稿日期: 2016-01-08
接受日期: 2016-05-11
亚洲叶猴社会行为学研究进展
韦周全1, 陆施毅2, 赵霏1, 李友邦1,3*     
1. 广西师范大学生命科学学院, 广西桂林 541006
2. 南京林业大学生物与环境学院, 南京 210037
3. 广西珍稀濒危动物生态学重点实验室, 广西师范大学, 广西桂林 541004
摘要: 叶猴以群居为主,个体间具有丰富的社会行为,包括相互理毛行为、等级关系、繁殖行为、杀婴行为和玩耍行为等。本文查阅了叶猴属Presbytis、乌叶猴属Trachypithecus和长尾叶猴属Semnopithecus社会行为的相关文献,综述社会行为所涉及的假说,分析叶猴个体间和猴群间社会行为的作用和功能,为今后国内叶猴或其他灵长类的研究提供参考和借鉴。
关键词亚洲叶猴     叶猴属     乌叶猴属     长尾叶猴属     社会行为    
Process in the Study on Social Behavior of Asian Leaf Monkeys
WEI Zhouquan1, LU Shiyi2, ZHAO Fei1, LI Youbang1,3*     
1. College of Life Sciences, Guangxi Normal University, Guilin, Guangxi Zhuang Autonomous Region 541006, China;
2. College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China;
3. Guangxi Key Laboratory of Rare and Endangered Animal Ecology, Guangxi Normal University, Guilin, Guangxi Zhuang Autonomous Region 541004, China
Abstract: Asian leaf monkeys, including genera Presbytis, Trachypithecus and Semnopithecus, are generally gregarious animals. Leaf monkeys have complex social behaviors, which have long been concerned. On the basis of previous relevant hypothesizes, this article summarized the process in the study on social behaviors of Asian leaf monkeys, including allogrooming, dominance, reproduction, infanticide and play. The current review provided primatologist with references for future study on social behaviors of leaf monkeys or other primates in China.
Key words: Asian leaf monkeys     Presbytis     Trachypithecus     Semnopithecus     social behavior    

叶猴隶属于猴科Cercopithecidae疣猴亚科Colobinae,为亚洲特有,包括叶猴属Presbytis、乌叶猴属Trachypithecus和长尾叶猴属Semnopithecus,共3属45种(Roos et al.,2014)。叶猴以群居为主,社群结构包括一雄多雌、多雄多雌和全雄群3种(黄乘明等,1996)。叶猴的社会行为可划分为2个层次,即个体间社会行为和群体间社会行为。叶猴的社群结构和社会行为与其他非人灵长类相比有其特殊的一面。本文对涉及叶猴社会行为研究进展的相关假说进行了总结,为今后同类物种的研究提供参考。

1 个体间相互行为 1.1 相互理毛行为

叶猴的理毛行为(grooming)可分为相互理毛行为(allogrooming)和自我理毛行为(autogrooming)(Hutchins & Barash,1976Dunbar,1991)。自我理毛行为是个体对自己的毛发进行梳理,有时从毛发中捡出小颗粒放进嘴咀嚼或用嘴咬食;相互理毛行为是个体间进行毛发梳理,并不时地从分开的毛发或露出的皮肤上捡出小颗粒放到嘴中咀嚼或直接用嘴咬食(Pérez & Vea,1998)。目前关于叶猴相互理毛行为的功能有3种假说:第一种假说是卫生功能假说(hygienic functional hypothesis),该假说认为相互理毛行为具有清洁毛发、除去皮肤寄生物和防止感染的功能(Barton,1985Borries,1992Borries et al.,1994)。许多研究表明相互理毛行为主要发生在个体无法或难以自我理毛的部位,如尾基部、背部和头等部位,对长尾叶猴S. entellus(Borries,1992Borries et al.,1994Koenig & Borries,2001)、黑叶猴T. francoisi(胡艳玲,2003周岐海等,2006)和戴帽叶猴T. pileatus(Kumar & Solanki,2014a)等的研究有力地支持了卫生功能假说;而Borries(1992)认为长尾叶猴的相互理毛行为是对无法自我理毛的一种补偿,这实际上也是卫生功能假说的进一步深化。第二种假说是缓和功能假说(distensive functional hypothesis),该假说认为不同个体间的相互理毛行为被认为能减少潜在攻击或消除被理毛者的抵触情绪,缓解个体间的紧张氛围,使之趋向缓和(Terry,1970)。在对长尾叶猴和白头叶猴T. leucocephalus的研究中得到证据(McKenna,1978张颖溢等,2001)。第三种假说是邓巴种群凝聚假说(Dunber’ s group-cohesion hypothesis),该假说认为相互理毛行为的时间与种群大小呈正相关,相互理毛行为不仅对社群成员间的凝聚力具有重要的作用,而且影响种群扩散和社群性比(Dunbar,1991Lehmann et al.,2007)。对叶猴相互理毛的时间分析发现叶猴需要通过高比值的相互理毛行为时间来保持社群成员间的凝聚力,相互理毛行为的时间比值是否影响社群大小和种群扩散模型仍需进一步的验证(Matsuda et al.,2015)。此外,一些研究还发现相互理毛行为影响繁殖行为,如长尾叶猴(Nikolei & Borries,1997)和戴帽叶猴(Islam & Husain,1982Kumar & Solanki,2014a)在交配前,雌性常对雄性进行理毛,而且戴帽叶猴的相互理毛行为中有21%回合发生在肛门-生殖区(Kumar & Solanki,2014a)。

1.2 等级关系

等级关系(dominance)普遍存在于群居的非人灵长类中(Maslow,1936Rowell,1974)。等级序位高的个体在享用资源和交配权中占有优势(赵海涛等,2011)。灵长类个体间的等级关系不仅有利于减少打斗和伤亡,保持社群稳定,而且能使弱者得到社群保护(李宏群等,2004)。在叶猴中,等级主要通过2种方式来判别,第一种方式是个体间的取代行为,即原来占据优势资源的个体被赶走并被取代,或是被其他个体趋近后短时间内主动让出原占有资源,通过计算个体间的取代矩阵来判别等级(张颖溢等,2001Lu et al.,2013)。在长尾叶猴(Koenig,2000Alam et al.,2015)和托马斯叶猴P. thomasi(Sterck & Steenbeek,1997)中,取代行为常发生在取食、占据食物斑块和空间位置等时;一些取代行为则发生在相互理毛行为(张颖溢等,2001)和性行为(Borries et al.,1991张颖溢等,2001Tiwary et al.,2012Alam et al.,2015)等社会行为中。第二种方式是个体间的攻击-屈服行为,这是个体竞争资源能力最直接的体现,通过计算个体间在资源竞争过程中攻击-屈服矩阵来判定(Koenig et al.,2004)。戴帽叶猴(Stanford,1991b)、黑叶猴(胡艳玲,2003)和菲氏叶猴T. phayrei(Koenig et al.,2004)个体间的攻击行为主要发生在食物出现时或饲喂时间段。虽然全雄群的社群成员组成较为松散,个体间的等级关系不明显(Mohnot,1984),但是首领猴通常领导猴群的活动,特别在入侵两性群时,首领猴会第一个移动(Minhas et al.,2010)。

1.3 繁殖行为

繁殖行为(reproduction behavior)是哺乳动物社会行为的重要组成部分,在叶猴两性群中,成年雌、雄个体会通过不同的行为来获得自身繁殖的成功。成年雄性会驱赶 群内即将性成熟的亚成年雄性(Rajpurohit et al.,1995),在雄性替换后,新主雄也有类似的行为,甚至会驱赶群内所有其他的雄性个体 (Rajpurohit & Sommer,1993);与怀孕的雌性相比,雄性与未怀孕可生育的雌性交配比例更高(Ostner et al.,2006);而一些研究则认为雄性在选择交配对象时偏好等级高个体而不是未怀孕的个体(Tiwary et al.,2012);成年雌性在发情期会对成年雄性进行邀配,这可能与群内成年雄性数量少有关,而邀配行为可提高雌性怀孕的概率,在银色乌叶猴T. cristatus(Bernstein,1968)、紫面叶猴S. vetulus(Rudran,1973)、长尾叶猴(Hrdy,1980Alam et al.,2015)、黑叶猴(梅渠年等,1987)和戴帽叶猴(Solanki et al.,2007)中均得到证实。

雄性叶猴用更多的时间和精力与雌性交配,抚育后代则主要由雌性完成(Jay,1963Hrdy,1980)。母猴对新生婴猴初期具有照顾、哺乳、携带和监督的作用(Poirier,1968Hrdy,1980Dolhinow & DeMay,1982Rajpurohit,1997黄乘明等,1998Zhao et al.,2009Kumar & Solanki,2014b),之后则是教授后代辨别食物、熟悉家域和训练技能等(Fairbanks,1990Zhao et al.,2009)。社群内非母亲成年或亚成年雌性参与抚育幼仔的行为称为阿姨行为或拟母亲行为(allomothering)(Horwich & Manski,1975Fairbanks,1990)。在叶猴中关于阿姨行为的社会功能有3种假说:第一种是联盟形成假说(the alliance formation hypothesis)(Hrdy,1976),该假说认为阿姨行为能促进其他雌性与幼仔母亲的社会联系,有利于提高行为发起者的等级,是雌性间的一种生殖合作(Hrdy,1976Stanford,1992Kumar & Solanki,2014b)。戴帽叶猴的阿姨行为使哺乳的雌性有更多的休息和取食时间(Stanford,1992),也有利于刚生育的母猴恢复体力(Kumar et al.,2005);雌性长尾叶猴间的婴猴转移行为可帮助母猴携带婴猴通过一些危险的地方(Minhas et al.,2010)。第二种假说是学习做母亲假说(the learning-to-mother hypothesis)(Hrdy,1980),该假说认为雌性在参与抚育幼仔的过程中可增加育幼经验,提高其将来成为母亲时育幼的成功率。在黑叶猴(胡艳玲等,2005)和白头叶猴(Jin et al.,2015)中无生育经验的雌性有更多的阿姨行为。第三种假说是婴猴受益假说(the infant benefit hypothesis)(Chism,2000),该假说认为表面上看实施阿姨行为的个体是一种利他行为,对实施阿姨行为的个体是纯损耗性的,但对婴猴而言,阿姨行为会增加对其的保护和照顾,有利于提高其成活率(Quiatt,1979Dolhinow & DeMay,1982Chism,2000)。

1.4 杀婴行为

杀婴行为(infanticide)是导致同种类幼仔或胎儿在短时间内死亡的行为(Hrdy & Hausfater,1984)。关于叶猴的杀婴行为,目前可归纳为3种假说:一是雄性繁殖策略假说(male reproductive hypothesis);二是减少资源竞争假说(reduce resource competition hyothesis);三是病态行为假说(pathological behavior hypothesis)。雄性繁殖策略假说认为雄性杀婴后,失去幼崽的雌性会提前进入发情状态,随之与其交配,缩短雌性生殖间隔,使雌性怀上其后代,有利于自身繁殖的成功,是目前灵长类杀婴行为的最重要解释(Hrdy,19741979)。在长尾叶猴(Maslow,1936Sugiyama,1965Sommer & Mohnot,1985Newton,1986Stanford,1991a;Rajpurohit et al .,2003; Sharma et al.,2010)、紫面叶猴(Rudran,1973)、银色乌叶猴(Wolf & Fleagle,1977Wolf,1980)、白头叶猴(Zhao et al.,2011Yin et al.,2013)、黑叶猴(Zhou et al.,2013)和约翰叶猴S. johnii(Kavana et al.,2014)等叶猴中均得到证实,杀婴是新主雄强烈的性冲动和迫切与雌性交配的结果(Maslow,1936),在长尾叶猴中有70%的雌性在失去婴猴8个月之后会有新的婴猴出生,刚好超过一个怀孕期(6.5个月)(Hrdy,1974)。减少资源竞争假说认为杀婴会减少潜在的竞争者,增加杀婴者和其后代对资源的获取,杀婴是种群密度过高的结果(Rudran,1973)。如长尾叶猴新主雄会攻击年龄较大的幼猴(Agoramoorthy,1994Sharma et al.,2010)。但该假说不能解释一些新主雄只攻击婴猴而不攻击年长的幼猴或亚成年猴(Rajpurohit et al.,2003)和发生在资源相对丰富地区的杀婴行为(Sharma et al.,2010)。病态行为假说认为杀婴是由于拥挤、人为干扰等因素引起雄性脾气暴躁、行为病态,从而伤及婴猴(Boggess,1979张鹏,2011)。相对雄性而言,雌性对后代的生殖和抚养投入更多的时间和精力,杀婴明显对雌性不利,为了减少杀婴行为,雌性采取的措施有:(1) 积极发情与新雄性交配(Hrdy,1979)。一些怀孕的雌性频繁与新主雄交配,并出现提前流产的现象(Agoramoorthy et al.,1988);(2) 迁移。如雌性带着婴猴离开社群或在群外围活动(Zhou et al. , 2013);未怀孕的雌性迁移到雄性能力更强的两性群,提高雄性对后代的保护能力(Wich & Sterck,2007);雌性通过迁移使种群数量适中,减少雄性的替换(Steenbeek & van Schaik,2001);(3) 混淆父子关系(van Schaik et al.,2004)。在多雄多雌群中杀婴的比率要低于一雄多雌群,这可能和雌性与群内所有成年雄性交配有关(Borries et al.,1999);通过对一群多雄多雌社群中长尾叶猴子代DNA分析发现,有超过21%基因为非群内雄性的基因,说明雌性还与群外雄性交配来混淆父子关系,减少了雄性取代后的杀婴行为(Launhardt et al.,2001);(4) 加强对婴儿的保护。在栗红叶猴P.rubicunda(Davies,1987)和托马斯叶猴(Steenbeek,1999)中,当两性群雄性替换之后,带婴猴的雌性会提高对新主雄的警戒,避免其伤害婴猴。

1.5 玩耍行为

玩耍行为(play behavior)是指由2个或多个个体共同参与的一种相互玩耍行为,个体间的行为相互影响(Jiang,2004),该行为在灵长类中表现尤为明显(Baldwin & Baldwin,1973)。玩耍行为常发生在婴猴和亚成年猴阶段,一般形式是打斗、逃跑和追逐(Pellis & Pellis,1998)。目前解释叶猴玩耍行为的假说是运动-训练假说(sports-training hypothesis),该假说认为玩耍是一种肢体活动,能提高个体身体协调性,增强体能,实践和提升运动、打斗和捕食等技巧(Byers & Walker,1995)。对长尾叶猴(Minhas et al.,2010)、金头叶猴T. poliocephalus(Schneider et al.,2010)、黑叶猴(江峡,2010黎大勇等,2013)和暗色叶猴T. obscurus(Karimullah et al.,2014)的研究均符合该假说;长尾叶猴(Minhas et al.,2010)和黑叶猴(黎大勇等,2013)中的雄性个体间有更多的打斗玩耍行为。栖息地质量影响着婴猴的玩耍行为,生活在高质量栖息地的雄性长尾叶猴与生活在贫瘠栖息地的相比,前者的玩耍频次为后者的6~7倍,内容更加丰富;随着雨季来临,食物种类的增加,后者的玩耍频次也随之大幅增加(Sommer & Mendoza-Granados,1995);在同一地域中,栖息地为城市的长尾叶猴与栖息地为农村的相比,前者的玩耍频次更高(Alam et al.,2015)。幼猴的玩耍行为受到母猴的限制,如银色乌叶猴(Amarasinghe et al.,2009)和长尾叶猴(Minhas et al.,2010)。

2 猴群间的社会行为 2.1 猴群间的冲突行为

叶猴的社群具有一定的家域性,在重叠地区猴群可能会相遇,在相遇初期常通过声音、视觉等信号进行警告(Poirier,1968),而一些成年雄性则会大声吼叫,如长尾叶猴和约翰叶猴(Hohmann,1989),雄性的叫声有利于减少与临近社群雄性的冲突(Wich et al.,2002)。若相互警告无效后,猴群间就会发生冲突。目前关于猴群间的冲突行为有几种假说,第一种假说是保卫配偶假说(mate resource defence hypothesis),该假说认为两性群中的雄性为了保护和占有群内的雌性,会攻击尝试与群内雌性交配的入侵成年雄性(David & Ehlers,2014),并控制群内雌性使其不迁移到其他猴群(Stanford,1991a)。而离开两性群的雄性为了提高入侵两性群的成功率,会通过组群的方式组成全雄群(Hrdy,1980)。在全雄群入侵时,不仅全雄群某个个体向两性群主雄发起进攻,而且全雄群所有个体会集体入侵,当雄性替换成功时,新主雄由全雄群中等级最高的雄性担任(Ostner et al.,2006)。在戴帽叶猴(Stanford,1991b)、托马斯叶猴(Steenbeek,1999Steenbeek et al.,1999)、长尾叶猴(Rajpurohit et al.,2003)、菲氏叶猴(Koenig & Borries,2012)和栗红叶猴(David & Ehlers,2014)中均得到证实。一些学者通过雄性间的打斗是否发生在其家域的核域部分,认为雄性对雌性的保护也是间接保卫食物(David & Ehlers,2014),这实际上也是保卫配偶假说的进一步探讨。第二种假说是保卫食物资源假说(food resource defence hypothesis),该假说认为两性群主雄为了保卫现有食物资源攻击其他入侵其家域的雄性,保护领域资源供群内雌性和后代使用(Sterck & Steenbeek,1997David & Ehlers,2014)。同时,叶猴群间为了减少遭遇,还有第三种假说,即威胁-水平假说(threat-level hypothesis)。该假说认为邻居或陌生者可能会与资源拥有者竞争,对领地的拥有程度反应了其威胁水平,更强的个体也意味着拥有更大的领地(Temeles,1994Müller & Manser,2007)。如菲氏叶猴雄性独猴减少在两性群家域边缘活动来避免与该群主雄发生冲突(Gibson & Koenig,2012)。

3 结论与展望

亚洲有45种叶猴,在一些物种中开展了长达几十年的积累研究(Borries et al.,1991),叶猴的社会行为研究取得了引人注目的成果,在相互理毛行为(Borries,1992Borries et al.,1994)、等级关系(Borries et al.,1991)、杀婴行为(Hrdy,19741979)和猴群间关系(David & Ehlers,2014)等方面的研究已经成为灵长类社会行为研究的重要组成部分,并形成了有价值的假说;国内叶猴分布点的确定(江海声等,1991王应祥等,1999Li et al.,2007)、物种的有效保护(黄乘明等,1998)和一些科研基地的建设(张颖溢等,2001Zhou et al.,2013)都为研究叶猴社会行为提供了坚实基础,我国在叶猴的社会行为研究也取得了重要的成果(张颖溢等,2001胡艳玲,2003Zhao et al.,2011黎大勇等,2013Yin et al.,2013Zhou et al.,2013Alam et al.,2015)。随着部分为解释叶猴社会行为而提出的假说在更多非人灵长类物种中得到验证,加强对叶猴社会行为的研究将有助于提高人们对非人灵长类社会行为的理解。

参考文献
胡艳玲, 黄乘明, 阙腾程, 等. 2005. 笼养黑叶猴拟母亲行为的观察[J]. 兽类学报, 25 (3):237–241.
胡艳玲. 2003. 笼养黑叶猴的社会关系和食量的研究[D]. 桂林:广西师范大学.
黄乘明, 卢立仁, 李春瑶. 1996. 论灵长类的婚配制度[J]. 广西师范大学学报(自然科学版) :78–83.
黄乘明, 卢立仁, 薛跃规. 1998. 白头叶猴的行为研究(Ⅱ)——白头叶猴的社群行为[J]. 广西师范大学学报(自然科学版), 16 (3):67–72.
江海声, 冯敏, 王骏, 等. 1991. 白头叶猴的分布及生态习性[J]. 兽类学报, 11 (3):236–237.
江峡. 2010. 三种笼养灵长类幼体的玩耍行为[D]. 桂林:广西师范大学.
黎大勇, 江峡, 黄乘明, 等. 2013. 笼养黑叶猴未成年个体的玩耍行为[J]. 四川动物, 32 (6):824–829.
李宏群, 张育辉, 李保国. 2004. 非人灵长类社会等级现象的研究进展[J]. 兽类学报, 24 (1):53–60.
梅渠年, 黄兴雅, 陈安杰. 1987. 圈养黑叶猴的繁殖[J]. 动物学杂志, 22 (1):33–35.
王应祥, 蒋学龙, 冯庆. 1999. 中国叶猴类的分类、现状与保护[J]. 动物学研究, 20 (4):306–315.
张鹏. 2011. 非人灵长类的杀婴行为及其适应意义[J]. 兽类学报, 31 (2):185–194.
张颖溢, 朱里忠, 秦大公, 等. 2001. 白头叶猴一个野生多雄多雌群的优势等级、亲密程度和梳理模式[J]. 北京大学学报(自然科学版), 37 (6):770–778.
赵海涛, 张剑, 朱紫瑞, 等. 2011. 非人灵长类雌性等级的研究方法[J]. 人类学学报, 30 (4):415–424.
周岐海, 黄乘明, 李友邦. 2006. 笼养黑叶猴的相互理毛行为[J]. 兽类学报 :221–225.
Agoramoorthy G, Mohnot SM, Sommer V, et al. 1988. Abortions in free ranging Hanuman langurs (Presbytis entellus)-a male induced strategy?[J]. Human Evolution, 3 (4): 297–308.
Agoramoorthy G. 1994. Adult male replacement and social change in two troops of Hanuman langurs (Presbytis entellus) at Jodhpur, India[J]. International Journal of Primatology, 15 (2): 225–238.
Alam MM, Jaman MF, Hasan MM, et al. 2015. Social interactions of Hanuman langur (Semnopithecus entellus) at Keshabpur and Manirampur of Jessore district of Bangladesh[J]. Bangladesh Journal of Zoology, 42 (2): 217–225.
Amarasinghe AAT, Botejue WMS, Harding LE. 2009. Social behaviours of captive Trachypithecus cristatus (Mammalia:Cercopithecidae) in the National Zoological Gardens of Sri Lanka[J]. Taprobanica, 1 (1): 66–73.
Baldwin JD, Baldwin JI. 1973. The role of play in social organization:comparative observations on squirrel monkeys (Saimiri)[J]. Primates, 14 (4): 369–381.
Barton R. 1985. Grooming site preferences in primates and their functional implications[J]. International Journal of Primatology, 6 (5): 519–532.
Bernstein IS. 1968. The lutong of Kuala Selangor[J]. Behaviour, 32 (1): 1–16.
Boggess J. 1979. Troop male membership changes and infant killing in langurs (Presbytis entellus)[J]. Folia Primatologica, 32 (1-2): 65–107.
Borries C, Launhardt K, Epplen C, et al. 1999. Males as infant protectors in Hanuman langurs (Presbytis entellus) living in multimale groups-defence pattern, paternity and sexual behaviour[J]. Behavioral Ecology and Sociobiology, 46 (5): 350–356.
Borries C, Sommer V, Srivastava A. 1991. Dominance, age, and reproductive success in free-ranging female Hanuman langurs (Presbytis entellus)[J]. International Journal of Primatology, 12 (3): 231–257.
Borries C, Sommer V, Srivastava A. 1994. Weaving a tight social net:allogrooming in free-ranging female langurs (Presbytis entellus)[J]. International Journal of Primatology, 15 (3): 421–443.
Borries C. 1992. Grooming site preferences in female langurs (Presbytis entellus)[J]. International Journal of Primatology, 13 (1): 19–32.
Byers JA, Walker C. 1995. Refining the motor training hypothesis for the evolution of play[J]. American Naturalist, 146 (1): 25–40.
Chism J. 2000. Allocare patterns among cercopithecines[J]. Folia Primatologica, 71 (1-2): 55–66.
David A, Ehlers S. 2014. Preliminary evidence for the hired guns hypothesis and indirect mate defence in a wild group of maroon langurs Presbytis rubicunda (Müller, 1838) in Sabangau Tropical Peat-swamp Forest, central Kalimantan, Indonesian Borneo[J]. Asian Primates Journal, 4 (2): 2–15.
Davies G. 1987. Adult male replacement and group formation in Presbytis rubicunda[J]. Folia Primatologica, 49 (2): 111–114.
Dolhinow P, DeMay MG. 1982. Adoption:the importance of infant choice[J]. Journal of Human Evolution, 11 (5): 391–420.
Dunbar RIM. 1991. Functional significance of social grooming in primates[J]. Folia Primatologica, 57 (3): 121–131.
Fairbanks LA. 1990. Reciprocal benefits of allomothering for female vervet monkeys[J]. Animal Behaviour, 40 (3): 553–562.
Gibson L, Koenig A. 2012. Neighboring groups and habitat edges modulate range use in Phayre's leaf monkeys (Trachypithecus phayrei crepusculus)[J]. Behavioral Ecology and Sociobiology, 66 (4): 633–643.
Hohmann G. 1989. Comparative study of vocal communication in two Asian leaf monkeys, Presbytis johnii and Presbytis entellus[J]. Folia Primatologica, 52 (1-2): 27–57.
Horwich RH, Manski D. 1975. Maternal care and infant transfer in two species of Colobus monkeys[J]. Primates, 16 (1): 49–73.
Hrdy SB. 1974. Male-male competition and infanticide among the langurs (Presbytis entellus) of Abu, Rajasthan[J]. Folia Primatologica, 22 (1): 19–58.
Hrdy SB. 1976. Care and exploitation of nonhuman primate infants by conspecifics other than the mother[J]. Advances in the Study of Behavior : 101.
Hrdy SB. 1979. Infanticide among animals:a review, classification, and examination of the implications for the reproductive strategies of females[J]. Ethology and Sociobiology, 1 (1): 13–40.
Hutchins M, Barash DP. 1976. Grooming in primates:implications for its utilitarian function[J]. Primates, 17 (2): 145–150.
Islam MA, Husain KZ. 1982. A preliminary study on the ecology of the capped langur[J]. Folia Primatologica, 39 (1-2): 145–159.
Jin T, Wang D, Pan W, et al. 2015. Nonmaternal infant handling in wild white-headed langurs (Trachypithecus leucocephalus)[J]. International Journal of Primatology, 36 (2): 269–287.
Karimullah, Anuar S, Bakhsh HM, et al. 2014. Social behaviors and nuisance activities of Trachypithecus obscurus in Bukit Juru Penang, Malaysia[J]. Journal of Chemical, Biological and Physical Sciences, 2 (1): 65–70.
Kavana TS, Erinjery JJ, Singh M. 2014. Male takeover and infanticide in Nilgiri langurs Semnopithecus johnii in the western Ghats, India[J]. Folia Primatologica; International Journal of Primatology, 85 (3): 164–177.
Koenig A, Borries C. 2001. Socioecology of Hanuman langurs:the story of their success[J]. Evolutionary Anthropology:Issues, News, and Reviews, 10 (4): 122–137.
Koenig A, Larney E, Lu A, et al. 2004. Agonistic behavior and dominance relationships in female Phayre's leaf monkeys-preliminary results[J]. American Journal of Primatology, 64 (3): 351–357.
Koenig A. 2000. Competitive regimes in forest-dwelling Hanuman langur females (Semnopithecus entellus)[J]. Behavioral Ecology and Sociobiology, 48 (2): 93–109.
Kumar A, Solanki GS, Sharma BK. 2005. Observations on parturition and allomothering in wild capped langur (Trachypithecus pileatus)[J]. Primates, 46 (3): 215–217.
Kumar A, Solanki GS. 2014a. Observation of grooming behaviour in wild capped langur Trachypithecus pileatus[J]. Journal of Primatology : 2.
Kumar A, Solanki GS. 2014b. Role of mother and allomothers in infant independence in capped langur Trachypithecus pileatus[J]. Journal of the Bombay Natural History Society, 111 (1): 3–9.
Launhardt K, Borries C, Hardt C, et al. 2001. Paternity analysis of alternative male reproductive routes among the langurs (Semnopithecus entellus) of Ramnagar[J]. Animal Behaviour, 61 (1): 53–64.
Lehmann J, Korstjens AH, Dunbar RIM. 2007. Group size, grooming and social cohesion in primates[J]. Animal Behaviour, 74 (6): 1617–1629.
Li Y, Huang C, Ding P, et al. 2007. Dramatic decline of Fransçois' langur Trachypithecus francoisi in Guangxi province, China[J]. Oryx, 41 (01): 38–43.
Lu A, Borries C, Caselli A, et al. 2013. Effects of age, reproductive state, and the number of competitors on the dominance dynamics of wild female Hanuman langurs[J]. Behaviour, 150 (5): 485–523.
Maslow AH. 1936. The role of dominance in the social and sexual behavior of infra-human primates:Ⅰ. observations at Vilas Park Zoo[J]. The Pedagogical Seminary and Journal of Genetic Psychology, 48 (2): 261–277.
McKenna JJ. 1978. Biosocial functions of grooming behavior among the common Indian langur monkey (Presbytis entellus)[J]. American Journal of Physical Anthropology, 48 (4): 503–509.
Minhas RA, Ahmed KB, Awan MS, et al. 2010. Social organization and reproductive biology of Himalayan grey langur (Semnopithecus entellus ajax) in Machiara National Park Azad Kashmir (Pakistan)[J]. Pakistan Journal of Zoology, 42 (2): 143–156.
Müller CA, Manser MB. 2007. ‘Nasty neighbours’ rather than ‘dear enemies’ in a social carnivore[J]. Proceedings of the Royal Society of London B:Biological Sciences, 274 (1612): 959–965.
Newton PN. 1986. Infanticide in an undisturbed forest population of Hanuman langurs, Presbytis entellus[J]. Animal Behaviour, 34 (3): 785–789.
Nikolei J, Borries C. 1997. Sex differential behavior of immature Hanuman langurs (Presbytis entellus) in Ramnagar, south Nepal[J]. International Journal of Primatology, 18 (3): 415–437.
Ostner J, Chalise MK, Koenig A, et al. 2006. What Hanuman langur males know about female reproductive status[J]. American Journal of Primatology, 68 (7): 701–712.
Pellis SM, Pellis VC. 1998. Play fighting of rats in comparative perspective:a schema for neurobehavioral analyses[J]. Neuroscience & Biobehavioral Reviews, 23 (1): 87–101.
Pérez A, Veà JJ. 1998. Cost-benefit analysis of allogrooming behaviour in primates[J]. Primates : 15–37.
Poirier FE. 1968. Nilgiri langur (Presbytis johnii) territorial behavior[J]. Primates, 9 (4): 351–364.
Quiatt D. 1979. Aunts and mothers:adaptive implications of allomaternal behavior of nonhuman primates[J]. American Anthropologist, 81 (2): 310–319.
Rajpurohit LS, Chhangani AK, Rajpurohit RS, et al. 2003. Observation of a sudden resident-male replacement in a unimale bisexual troop of Hanuman langurs, Semnopithecus entellus, around Jodhpur (India)[J]. Folia Primatologica, 74 (2): 85–87.
Rajpurohit LS, Sommer V, Mohnot SM. 1995. Wanderers between harems and bachelor bands:male Hanuman langurs (Presbytis entellus) at Jodhpur in Rajasthan[J]. Behaviour, 132 (3): 255–299.
Rajpurohit LS, Sommer V. 1993. Juvenile male emigration from natal one-male troops in Hanuman langurs[M]//Pereira ME, Fairbanks LA. Juvenile primates:life history, development and behaviour, with a new foreward. Chicago:University of Chicago Press:86-103.
Rajpurohit LS. 1997. Why do mothers carry the corpses of their infants in Hanuman langurs, Presbytis entellus[J]. Journal of Nature Conservation : 183–193.
Roos C, Boonratana R, Supriatna J, et al. 2014. An updated taxonomy and conservation status review of Asian primates[J]. Asian Primates Journal, 4 (1): 2–38.
Rowell TE. 1974. The concept of social dominance[J]. Behavioral Biology, 11 (2): 131–154.
Rudran R. 1973a. Adult male replacement in one-male troops of purple-faced langurs (Presbytis senex senex) and its effect on population structure[J]. Folia Primatologica, 19 (2): 166–192.
Rudran R. 1973. The reproductive cycles of two subspecies of purple-faced langurs (Presbytis senex) with relation to environmental factors[J]. Folia Primatologica, 19 (1): 41–60.
Schneider I, Tielen IHM, Rode J, et al. 2010. Behavioral observations and notes on the vertical ranging pattern of the critically endangered Cat Ba langur (Trachypithecus poliocephalus poliocephalus) in Vietnam[J]. Primate Conservation, (25): 111–117.
Sharma G, Ram C, Rajpurohit LS. 2010. A case study of infanticide after resident male replacement in Semnopithecus entellus around Jodhpur (India)[J]. Proceedings of the Zoological Society, 63 (2): 93–98.
Solanki GS, Kumar A, Sharma BK. 2007. Reproductive strategies of Trachypithecus pileatus in Arunachal Pradesh, India[J]. International Journal of Primatology, 28 (5): 1075–1083.
Sommer V, Mendoza-Granados D. 1995. Play as indicator of habitat quality:a field study of langur monkeys (Presbytis entellus)[J]. Ethology, 99 (3): 177–192.
Sommer V, Mohnot SM. 1985. New observations on infanticides among hanuman langurs (Presbytis entellus) near Jodhpur (Rajasthan/India)[J]. Behavioral Ecology and Sociobiology, 16 (3): 245–248.
Stanford CB. 1991a. The capped langur in Bangladesh:behavioral ecology and reproductive tactics[M]. Basel, Switzerland: Karger Medical and Scientific Publishers .
Stanford CB. 1991b. Social dynamics of intergroup encounters in the capped langur (Presbytis pileata)[J]. American Journal of Primatology, 25 (1): 35–47.
Stanford CB. 1992. Costs and benefits of allomothering in wild capped langurs (Presbytis pileata)[J]. Behavioral Ecology and Sociobiology, 30 (1): 29–34.
Steenbeek R, Piek RC, Van Buul M, et al. 1999. Vigilance in wild Thomas's langurs (Presbytis thomasi):the importance of infanticide risk[J]. Behavioral Ecology and Sociobiology, 45 (2): 137–150.
Steenbeek R, van Schaik CP. 2001. Competition and group size in Thomas's langurs (Presbytis thomasi):the folivore paradox revisited[J]. Behavioral Ecology and Sociobiology, 49 (2-3): 100–110.
Steenbeek R. 1999. Tenure related changes in wild Thomas's langurs Ⅰ:between-group interactions[J]. Behaviour, 136 (5): 595–625.
Sterck EHM, Steenbeek R. 1997. Female dominance relationships and food competition in the sympatric Thomas langur and long-tailed macaque[J]. Behaviour, 134 (9): 749–774.
Sugiyama Y. 1965. On the social change of Hanuman langurs (Presbytis entellus) in their natural condition[J]. Primates, 6 (3): 381–418.
Temeles EJ. 1994. The role of neighbours in territorial systems:when are they ‘dear enemies’[J]. Animal Behaviour, 47 (2): 339–350.
Terry RL. 1970. Primate grooming as a tension reduction mechanism[J]. The Journal of Psychology, 76 (1): 129–136.
Tiwary CB, Kumar N, Kumar R. 2012. Sexual behavior in Hanuman langur (Semnopithecus entellus:primate) female under captive conditions[J]. Indian Journal of Applied & Pure Biology, 27 (2): 235–241.
van Schaik CP, Pradhan GR, van Noordwijk MA. 2004. Mating conflict in primates:infanticide, sexual harassment and female sexuality[M]. Cambridge, UK: Cambridge University Press: 131 -150.
Wich SA, Assink PR, Becher F, et al. 2002. Playbacks of loud calls to wild Thomas langurs (Primates; Presbytis thomasi):the effect of familiarity[J]. Behaviour, 139 (1): 79–87.
Wich SA, Sterck EHM. 2007. Familiarity and threat of opponents determine variation in Thomas langur (Presbytis thomasi) male behaviour during between-group encounters[J]. Behaviour, 144 (12): 1583–1598.
Wolf K. 1980. Social changes and male reproductive strategy in silvered leaf monkeys, Presbytis cristate, in Kuala Selangor, Peninsuular Malaysia[J]. American Journal of Physical Anthropology, 52 (2): 294.
Wolf KE, Fleagle JG. 1977. Adult male replacement in a group of silvered leaf-monkeys (Presbytis cristata) at Kuala Selangor, Malaysia[J]. Primates, 18 (4): 949–955.
Yin L, Jin T, Watanabe K, et al. 2013. Male attacks on infants and infant death during male takeovers in wild white-headed langurs (Trachypithecus leucocephalus)[J]. Integrative Zoology, 8 (4): 365–377.
Zhao Q, Borries C, Pan W. 2011. Male takeover, infanticide, and female countertactics in white-headed leaf monkeys (Trachypithecus leucocephalus)[J]. Behavioral Ecology and Sociobiology, 65 (8): 1535–1547.
Zhao Q, Jin T, Wang D, et al. 2009. Lack of sex-biased maternal lnvestment in spite of a skewed birth sex ratio in white-headed langurs (Trachypithecus leucocephalus)[J]. Ethology, 115 (3): 280–286.
Zhou QH, Luo B, Huang CM. 2013. Attacks on adult females with infants by non-resident males in the François langur[J]. Zoological Research, 34 (1): 9–12.