The function of female copulation calls
Teija Nugraha Febranouva, Master student, Bogor Agricultural University, Indonesia
Little is known about the functional significance of female primate copulations calls. One of the current hypothesis is that these calls reliably indicate the fertile phase of a female reproductive cycle. Another one suggests that these calls play an important role in post-copulatory sexual selection processes, depending on the degree of promiscuity in the species. Empirical evidence in support of any of the assumptions, however, is still largely missing. The aim of this project is to investigate the use and information content of female copulation calls in order to test the two hypotheses, and to compare these signals with female sexual swellings. For this, we combine behavioural observations with acoustic analysis and playback experiments, and with an objective measurement of female sexual swellings using digital pictures.
Female social relationships
Julie Duboscq, PhD student, German Primate Center, Germany in collaboration with Bernard Thierry, DEPE-CNRS-Strasbourg University, France and Oliver Schuelke, CRC "Evolution of Social Behaviour", Göttingen, Germany
Social relationships among female primates reflect a complex combination of competitive and cooperative strategies. Socioecological models (Wrangham 1980, van Schaik 1989, Isbell 1991, Sterck et al. 1997) and the covariation hypothesis (Matsumura 1999, Thierry 2000) provide two different frameworks to explain the diversity of female social relationships in primates. Several predictions have been made from these hypotheses and studies testing the validity of the models have not always been successful.
The aim of this study is to collect data on female social behaviours, female feeding competition and food ecology in a macaque species that has rarely been studied in the wild and that has been categorised as "resident-nepotistic-tolerant" (Sterck et al., 1997) or "grade-4" social organization (Thierry, 2000). Results will enable us to test the predictions of the different hypotheses and to better understand the evolution of the social system in macaques.
Male offspring relationships
Daphne Kerhoas, PhD student, German Primate Center, Germany in collaboration with Anja Widdig, MPI-EVA, Germany
Achievement and maintenance of dominance in males
Christof Neumann, PhD student (in collaboration with Anja Widdig, MPI-EVA)
The aim of this study is to examine the determinants of a male’s position within a group’s dominance hierarchy and its effect on reproductive success. Questions that will be addressed are in particular:
(1) do individual features, such as age, body size/weight, androgen status, canine condition, characteristics of sexual signals (loud calls, sex skin colouration), personality etc. affect a male’s dominance rank,
(2) how important are male coalition partners for the achievement and maintenance of high rank,
(3) how important is female support for the achievement and maintenance of high rank,
(4) how stable are male hierarchies in time,
(5) what is the effect of rank on reproductive success.
Female sexual behaviour during ovarian cycles
Britta Rohr, Diploma student, Free University of Berlin, Germany, completed
So far, relatively little is known about the strategic significance of female reproductive behaviour. Furthermore, the functional significance of female sexual swellings and promiscuity remains still unknown. Both female traits may serve as a female counter-strategy against male infanticide by confusing paternity. The present study aims at characterising and exploring the sexual behaviour and sexual swellings of adult females during ovarian cycles in order to clarify to what extent females of this species are able to pursue their own reproductive strategies and what these strategies are. For this, we combine behavioural observations with taking digital photographs from female sexaul swellings.
Development of female sexual traits during adolescence and male response
Stefan Wedegärtner, Diploma student, Free University of Berlin, Germany
Basic knowledge of species specific reproductive parameters is essential for effective conservation. In this study, the ontogenetic development of specific female sexual traits during adolescence is investigated. Combining observations of female sexual behaviour, objective measurements of sex skin swelling sizes and acoustic analysis of copulation calls, these traits will be characterised in adolescent females and their development monitored. In addition, male sexual interest into adolescent females will be observed in order to increase our understanding of the functional significance of these traits as part of a female reproductive strategy.
The effect of mothering and allomothering style on infant development
Kristin Hagel, Bachelor student, Free University of Berlin, Germany
One phenomena observed in primate groups is that females care for infants that are not their own (allomothering). In this way, infants may receive extra care and get the opportunity to build early bonds to non-mothers. On the other hand, allomothering may be costly for infants if care is not appropriate. To which degree infants are handled by non-mothers depends on maternal permissiveness/restrictiveness.
This study investigates the costs and benefits of mothering and allomothering style on infant development. Behavioural observations focus on interactions between infants and female group members, infant social development as well as motorical and foraging behaviour. In addition, infant physical development is documented through regular photographs taken with a digital camera.
Daily activity, home range use and feeding behaviour of two groups in mixed habitat
Hani Pontororing, Master student, Universitas Sam Ratulangi, Manado, Indonesia, completed and Giyarto, Universitas Gadja Mada, Yogyakarta, Indonesia, completed
The Sulawesi macaques have only rarely been studied in the wild and knowledge about their ecological characteristics as well as flexibility, vulnerability and response to habitat disturbance and human contact is still largely missing though essential for conservation actions. This study aims at characterising the ecology of two macaque groups living in a semi-disturbed habitat. The home range of both groups comprises primary and secondary forest as well as scrub/grassland. We collected data on daily activity, spatial and f eeding behaviour of individuals distinguishing between three age/sex classes (adult males, adult females, juveniles). Data collected during the dry season (H.P.) has been compared with data of the rainy season (G.) and with data formerly collected in this area to identify differences in behaviour due to changes in environment.
Loud calls: contextual differences in structure and response of group mates
Christof Neumann, Master student, University of Leipzig/German Primate Center, Germany, completed
In many primate species male individuals produce vocalizations that can be heard over a long distance (loud or long calls). Results of a recent meta-analysis suggest that these calls serve different purposes in different species. In Sulawesi crested black macaques loud calls are emitted in a variety of contexts including agonistic interactions and mating, but also socially neutral behaviour.
The aim of this study was to examine individual and contextual differences in call structure by detailed sound analysis. Behavioural observations helped clarifying individual and context depending differences in frequency of call utterance. With playback experiments, we tested how group mates differ in their response to the calls.
Rank dependant differencesin frequency and acoustic structure of loud calls
Gholib Assahad, Bachelor student, Bogor Agricultural University, Indonesia, completed
In contrast to other male macaques, all adult male Sulawesi crested black macaques utter loud calls. It is thus very likely that in this species loud calls serve a function in inter- and/or intra-sexual selection, i.e. function to attract fertile females and/or play a role for male-male competition.
The aim of this study was to investigate the relationship between male dominance rank and the frequency and acoustic structure of loud calls. In addition, we examined response of group mates to calls. We combined behavioural observations with sound analysis and playback experiments.