Communal roosting and formation of sleeping clusters in barbary macaques (Macaca sylvanus).код для вставкиСкачать
American Journal of Primatology 28271-280 (1992) Communal Roosting and Formation of Sleeping Clusters in Barbary Macaques (Macaca sylvanus) VIVEKA ANSORGE, KURT HAMMERSCHMIDT, AND DIETMAR TODT Institut fur Verhaltensbiologie,Freie Uniuersitat Berlin, Berlin 41, Germany Sleeping cluster composition and distribution were studied in a semi-freeranging population of 174 Barbary macaques (Macaca sylvanus) in Rocamadour/France. Over a period of 2 months 341 sleeping clusters comprising 754 animals were recorded as animals left the sleeping trees. To control for nocturnal activities five observation periods were conducted, each of which covered a complete night. Sleeping partners were selected from a particular set of individuals. From night to night there was considerable fluctuation among the individuals, which finally formed a sleeping cluster. Preferred size of sleeping clusters was two and three individuals per cluster. The majority of females spent the nights in body contact to infants or female juveniles; whereas males either slept alone or with older male juveniles. Adult males and females never shared a sleeping cluster. During the night the animals showed hardly any locomotive and vocal activity. Sleeping clusters remained stable until dissociation the next morning. o 1992 Wiley-Liss, Inc. Key words: social behavior, nocturnal activity, roosting sites INTRODUCTION Sleeping clusters, in which individuals spend extended time in body contact, are characteristic of most primate species [citations in Anderson, 19841 and represent an important part of social behavior. Spacing behavior, in the context of communal roosting as well as individual sleeping partner choice, is closely correlated to the species-specific social network, as documented for Perodicticus potto [Clauss et al., 19811,Miopithecus talapoin [Gautier-Hion, 19701,Papio papio [Dunbar & Nathan, 1972; Anderson & McGrew, 19841, Papio hamadryas [Kummer, 19681,Papio cynecephalus [Rasmussen, 19791,Cercopithecus petaurista [Todt et al., 19823,Macaca mulatta [Vessey, 19731,Macaca sylvanus [Todt et al., 1984; Ansorge & Hammerschmidt, 1987; Ansorge, 19891, Symphalangus syndactylus [Chivers, 19711, and Pan troglodytes [Riss & Goodall, 19761. There is no doubt about the ecoethological functions of communal roosting [review in Anderson, 19841, but the social correlates and the intra-group consequences are unclear. Whereas there are several studies on the daytime social network of Barbary Received for publication April 9, 1991; revision accepted April 17, 1992. Address reprint requests to Viveka Ansorge, Institut fur Verhaltensbiologie, Freie Universitat Berlin, Haderslebenerstr. 9, 1000 Berlin 41, Germany. 0 1992 Wiley-Liss, Inc. 272 I Ansorge et al. ENTRANCE C -A 200 m Fig. 1. “La For&t des Singes” i n RocamadouriFrance lmodified from De Turckheim & Merz, 19841. The park consists of 10 fenced ha ofjuniper scrub, open meadow, and oak forest (part A,B,C). The preferred sleeping site was part A. Data recording took place in two areas ( a l , a2). For a detailed description of “La for& des singes” see De Turckheim and Merz [ 19841. macaques [Deag, 1974; Deag & Crook, 1971; Taub, 1978,1984; Wolff & Todt, 1985; Kuster & Paul, 1986; Timme, 1989; Small, 1990a,bl little has been published about their nighttime relationships [Ansorge & Hammerschmidt, 1987; Ansorge, 19891. In this paper we present data on Barbary macaque’s nocturnal behavior: 1)nocturnal activity, 2) age and sex composition of sleeping clusters, and 3) constancy in partner choice. MATERIALS AND METHODS Study Animals and Study Site The study was conducted on semi-free-ranging Barbary macaques (Macaca sylvanus) a t “La For& des Singes,” Rocamadour, France (Fig. 1). The population of Rocamadour was established in 1974, and has been the subject of various research projects [Todt et al., 1984; Todt & Pohl, 1985; Wolff, 1985; Lehmann, 1989; van den Bergh, 1989; Ansorge, 1989; Hammerschmidt & Ansorge, 1989; Small, 1990a,b; Hammerschmidt, 19901. “La Foret des Singes” is a visitor park were the monkeys range freely while the visitors are restricted to a path (see dashed line in Fig. 1). Thus the animals can easily avoid contact with humans but are completely habituated to their presence. The size of the park allows the monkeys to choose different areas for sleeping and for daytime activities. The oak trees (part A, B, C in Fig. 1)have a height of about 10-15 m and are easy to survey. The animals feed on natural vegetation, on monkey chow which is placed in feeder huts, on grain seeds, and on apples which are spread throughout the park. For further details of park management see Small [199Obl. Data were recorded during the birth season in spring 1987 (April to July). At Roosting Behavior in Barbary Macaques / 273 TABLE I. M m a c a syluanus Population of “La For& des Singes” During the Birth Season 1987 (Newborns excluded)* Males Females Sum 12 12 24 9 17 26 7 10 17 9 6 15 13 17 30 11 25 36 *The discrete age classes are due to the birth season. N = 148. the end of the season the population consisted of 174 individuals, including 26 newborns. For the age profile used in this paper we distinguished the following classes: infants (0-3 months), juveniles (age 1-3 years for females and 1-4 years for males) and adults (Table I). As Barbary macaques are seasonal breeders [Kiister & Paul, 19841siblings are at least 1or 2 years apart. Therefore observed differences between young group members (juveniles and infants) permit the marking of clear age differences. Data Sampling A sleeping cluster was defined as animals roosting in body contact. A sleeping group was defined as an aggregation of several clusters which were spatially separated. According to the different properties of the areas a l and a2 (Fig. 1) the distances between clusters within a group as well as the distances between sleeping groups varied. In attempting to note the sleeping places and constellations it was impossible to survey all 174 animals a t once. Hence we had to find a way to take a random sample each day. To do this we selected five adult individuals (all were males) as focals and followed one of them each evening (focal animal observation) until it formed a stable sleeping cluster. Then we did a statistical survey the next morning of the animals that surrounded the observed male. We selected male focals as earlier observations in 1986 had shown that, although they frequently slept alone, they are just as spatially well integrated in the sleeping group as females. Each morning, before sleeping clusters disbanded we noted sex, age-class, spatial position, and, where possible, the identity (30% of a total of 754 registered animals) of all animals roosting up to 20 m around the focal animal. Because of the darkness only adult animals could be identified. Data were recorded on 47 days; 754 animals were recorded distributed in 341 sleeping clusters. We also conducted 5 all-night observations lasting from dusk until dawn (9 hours). A selected number of subjects (selection see above) was observed (event sampling) after the termination of the focal observation. All activities including vocalizations (mean: 21.8 per night) were recorded. As a measure of vocal activity the minutes where any vocal pattern was uttered were counted throughout the night. Each animal that vocalized in the same minute was counted as if it were a seperate event. During the five nights we totaled 109 observations of animals. RESULTS Nocturnal Activity In all night observations the monkeys were generally quiet and rarely showed activity. They did not change their sleeping places. If a short dissociation occurred they always returned to their original places. The majority of nocturnal disturbances were caused by young group members. Usually one member of a cluster 274 I Ansorge et al. changed position. As a result other members of that cluster, in most cases juveniles or infants, vocalized or even left the group for a short moment (<1min). This kind of movement was observed 184 times (1.5 movements per animal in five nights); 62.5% of these movements were due to juvenile or infant activities. Accordingly 94.9% of the registered vocalizations (total: 361) were uttered by juveniles or infants. Vocalizations usually ended when a cluster had reassembled after a short dissociation or in, other words, when the adult of a group had reaccepted the protesting youngster in his huddle. Roosting Sites In spring 1987 the entire population roosted in part A of the park (Fig. 1). Our recorded data refer to the areas a1 and a2. These areas were separated by a trail and a number of trees which were not used for roosting. Within these areas some trees were used more frequently than others, and there was considerable fluctuation in the occupation of marginal trees. Within the same area, spatial distances between sleeping clusters varied between 0.5 and 30 m (al: mean distance of the nearest neighbour of each group: 4.84, SD: 4.16; a2: mean: 5.84, SD: 4.48). Both areas had a batch of young saplings which were not suitable for sleeping purposes; thus there were always unoccupied trees, on average one-third. The 341 sleeping clusters were distributed among 286 trees; 225 trees were occupied by a single cluster. More than three clusters per tree were never observed. Most of the individually known animals preferred one area. This distribution of sleeping places correlated with the membership in different subgroups which developed during the following years. In spring 1989 a stable subgroup roosted separately from the other group in part B of the park. Most animals that preferred area a1 in spring 1987 were now members of this subgroup. Composition of Sleeping Clusters In the choice of cluster sizes the animals showed clear preferences. In the following the observed and expected number of clusters for each size is given: 80 single clusters (expected: 188.51, 175 dyads (exp.: 94.25), 80 triads (exp.: 62.71, 21 tetrades (exp.: 47). This result is significant (chi2 = 149.6, P < .001). Whereas dyads and triads were preferred the macaques avoided to sleep alone or in a tetrade. Most of those individuals that spent the night alone were adult males. These singly sleeping males constituted 40% of all males, whereas only 10% of the adult females or older juveniles were found roosting alone (Fig. 2). Both adult males and females preferred t o form a cluster with one or two non-adults. Here, males showed a preference for older juveniles (2 to 4 years of age), whereas females preferred yearlings or infants. In triads and tetrades the two younger sleeping partners of an adult female predominantly differed in age (83% of 107 juveniles). In contrast only about half of the juveniles roosting together or in a sleeping cluster with an adult male differed in age (male-juvenile-clusters: 49%, n = 31; all-juvenile-clusters: 53%, n = 79). With respect to the sex of sleeping group members we found a clear cut distribution: Adult females did not roost together with adult males and the majority of adult-juvenile clusters were comprised of members belonging to the same sex (86%of 126juveniles). However, due to the difficulty in identifying a juvenile’s sex at dawn, the latter result refers to a limited amount of material (n = 126 juveniles). Exceptions from clusters with members of the same sex were observed in Roosting Behavior in Barbary Macaques I 275 Sleepingpartner choice Distributionof s l e e p i n g c l u s t e r size 'A 1'" QP 50 dc7 ns 2s 155 J1 n = 133 --SO J2 n = 122 25 .- - lnf J1 11.1 JZ J3& '$ C? I -so J3/4 n = 93 25 Fig. 2. Sleeping partner choice in dyads. Bars indicate the percentage of sleeping partners belonging to the respective age and sex class. The circles give the distribution of sleeping cluster size for each age and sex class. Size = 1,W, 2, M; 3, m; 4, 0. mother-offspring clusters (male infants), or as individual idiosyncrasies: For example, the oldest adult male in Rocamadour had developed the unusual habit of spending the night with one or two juvenile females. 276 I Ansorge et al. 2 C W 2 W E 60 .c 5) W > L W 50 0 40 30 20 10 10 20 30 40 50 expected frequency Fig. 3. Correlation of the observed and expected frequency of cluster composition types. Cluster types with observed or expected frequency below 5 are as follows: F + F + ;F + FJ; MMM; F + J J ; F J J J ; MJJJ; MMMJ; JJJJ. Expected frequency: e = p ( n ai)*q. p ( n a,) = probability that a member of a certain age and sex class (i) is in the cluster (based on the age and sex profile of the entire population, Table I); nJ = observed frequency (n) of different cluster sizes 0’). Figure 3 illustrates the preference for certain cluster types and reveals a further aspect: Females with newborns (F+ 1 avoided additional sleeping partners, whereas those without newborns favoured clusters with more than one partner. Constancy in Sleeping Partner Choice We analyzed data of all individually known animals. As mentioned above these were only adults and covered 30%of the whole population. Sleeping partners were not selected at random. Figure 4 shows for 31 individually known animals the following correlation: The greater the number of observation days, the greater is the number of differing sleeping partners of an animal. The adult males that sleep alone constitute an exception (diamonds on the zero-axis). If one excludes these adult males from the sample in Figure 4 this correlation is highly significant (r = 5 7 , P < .01; Pearson’s correlation coefficient). Of course, the number of different sleeping partners is limited, because the animals most probably choose from a confined circle of animals with whom they are well familiar. But only a few days of observation suffice to register a considerable fluctuation in sleeping partner choice. A similar dynamic was apparent in the choice of roosting places: Normally, a monkey did not spend two or more successive nights in the same tree although Roosting Behavior in Barbary Macaques / 277 q 5 * * * * . . 0 0 3 6 9 12 15 days of observation Fig. 4. Fluctuation in sleeping partner choice. Correlation of the number of different sleeping partners with days of observation. The data sample refers to all individually known animals which were seen more than once in the morning sample. there seemed to be individual preferences for certain trees. Changes in roosting places were presumably related to changes in partner choice. DISCUSSION It is clear that communal roosting in primates contributes to a number of ecological and social functions [Anderson, 19841. Communal roosting occurs in connection with common access to food resources or restricted sleeping lodges such as trees or cliffs. Obvious consequences of communal roosting in terms of social functions are an increased number of potential contact partners and therefore increased information transfer about various kinds of social states (e.g., rank, role, kinship, sexual state). Establishment of Subgroups Among primates several roosting sites in the home range of a group are common and different groups of the same population with overlapping home ranges may compete over roosting sites [see Anderson, 19841. The occurrence of changes in the use of certain roosting sites may not only depend on basic properties of the respective home ranges or habitats. They may point to other factors which might have caused them. During our study on the Barbary macques in Rocamadour we observed the establishment of a novel subgroup. This consisted of 40 individuals, which 1 year later roosted some 100 meters apart from the original roosting site still used by the rest of the population (see part A and B, Fig. 1). The spatial distribution of sleeping clusters reflects the beginning of the splitting process as described also for other species [Bouliere et al., 1970; Eisenberg et al., 1972; McGuire et al., 1974; Ransom, 19811. This indicates that changes of social relations preceeded the group splitting. Adult-Juvenile Male Bonds Males showed a strong inclination to associate with older juvenile males in a sleeping cluster and vice versa. A comparable result could not be found in other species [Gautier-Hion, 1970; Dunbar & Nathan, 1972; Vessey, 1973; Clauss et al., 1981; Anderson and McGrew, 19841. Barbary macaque males build close relationships with infants and the bonds between adult males and juvenile males continue with growing age of the juveniles 278 I Ansorge et al. [Paul, 1984; Bartecki, 19861. However, still 40%of the adult males slept alone. A similar result was found for rhesus macaques [Macaca mutlatta: Vessey, 19731, Talapoins [Miopithecus talapoin: Gautier-Hion, 19701, and Pottos [Perodicticus potto M: Clauss et al., 19811. Fluctation in Partner Choice Our data show that the animals alternate between sleeping partners. Still we cannot present enough observations about individually known subjects (Fig. 4) to draw a conclusion about the total number of potential sleeping partners for one individual. It would be an interesting enrichment of the knowledge of social behavior to compare the social circle a t night with that during daytime. However, we can state that the observed fluctuation in partner choice arose partly from juveniles looking for alternative sleeping partners after rejection by their mothers. The likelihood that a mother will reject her older infant may increase after she gives birth to her next offspring since mothers with newborns avoid additional sleeping partners. Our data suggest that juvenile males are therefore forced to find new sleeping partners whereas juvenile females can return to their mother’s sleeping cluster. The separation of infants from their mothers as their nightly sleeping partner takes place later than weaning, which has its peak around the age of 6 months when Barbary macaque mothers become sexually active [Paul, 1984; Timme, 19891. Matrilineal Kinship As in other species of the genus Macaca, there is a strong matriline in Barbary macaque populations and a linear rank order dominates the social life of females [Deag, 1974; Kiister & Paul, 1986; Small, 1990bl. Daytime behavior shows that familarity between individuals corresponds to kinship and is reflected by the amount of affiliative behavior among group members [Wrangham, 1983; Bartecki, 1986; Steuckardt, 1989; Timme, 1989; Small, 1990a,bl. We cannot present data about kin since it was not possible to identify young group members in the dark. However, we found out that with the exception of infants, youngsters in a sleeping cluster were predominantly of the same sex. In triads and tetrades the two younger sleeping partners of an adult female predominantly differed in age (83% of 107 juveniles). In contrast only about half of the juveniles roosting together or in a sleeping cluster with an adult male differed in age (male-juvenile-clusters:49%, n = 31; all-juvenile-clusters: 53%, n = 79). The age and sex ratio of female-juvenile triads and tetrades allow the assumption that most of them were sisters with their mother. CONCLUSIONS 1. Compared to other species there was a high frequency of male-juvenile clusters. This might be a consequence of the close male-infant relationship which are characteristic for Barbary macaques. 2. Juveniles that roosted with adult females or males were predominantly of the same sex as the adults. The sex-specific division in sleeping partner choice as well as the age structure of female-juvenile clusters may correlate to the matrilineal structure of Barbary macaque populations. 3. The fluctation in sleeping partner choice may enhance the variety of social relationships beyond the mother-infant dyad. This increases the social knowledge about other group members and strengthens group bonds. Roosting Behavior in Barbary Macaques / 279 4. A spatial aggregation of sleeping clusters might indicate the establishment of a new social subgroup. ACKNOWLEDGMENTS We thank Ellen Merz and Gilbert de Turckheim for permission to study a t “La Foret des Singes,” and Lucien Ambiehl for cooperation a t the park and hospitality at his campground; Henrike Hultsch and Gottfried Wiedenmann for comments on the manuscript; and Kurt Kaemmerer for assistance with the English version. REFERENCES Anderson J.R. Ethology and ecology of sleep in monkeys and apes. ADVANCES IN THE STUDY OF BEHAVIOR. 14:165229,1984. Anderson. J.R.: McGrew. W.C. Guinea baboons (Papio‘papio) a t a sleeping site. AMERICAN JOURNAL OF PRIMATOLOGY 6:l-14. 1984. Ansorge, V.‘ ALTERS-UND GESCHLECHTSSTRUKTUR DER SCHLAFGRUPPEN BE1 BERBERAFFEN (MACACA SYLVANUS). Diplom-thesis, FB Biologie, Freie Universitat Berlin, Germany, 1989. Ansorge, V; Hammerschmidt, K. Schlafsylvanus): Ingruppen bei Berberaffen (M. tegrationsprobleme juveniler Tiere und deren kommunikativer Losungsansatz. DT. GES. SAUGETIERKD., 61 HAUPTVERSAMMLUNG, Berlin, Germany, P. 6, 1987. Bartecki, U. The social position of male Barbary macaques (Mucacu syluanus) in a semifree-raneina DoDulation. PRIMATES 27:173-183, ?9&6.Bouliere, F.; Hunkeler, C.; Bertrand, M.; Ecolom and behavior of Lowe’s menon (CercGjithecus cumpbelli lowei) in t& Ivory Coast. Pp.279-333 in OLD WORLD MONKEYS: EVOLUTION, SYSTEMATICS, AND BEHAVIOR.J.R. Napier; P.H. Napier eds. New York, Academic Press, 1970. Chivers, D.J. Spatial Relations Within the Siamana Group. PROCEEDINGS OF THE ~ R D INTERNATIONAL CONGRESS OF PRIMATOLOGY, ZURICH 3: 14-21,1971. Clauss, G.; Hultsch, H.; Duvall, F.; Todt, D. Factors influencing choice and social utilization of resting places in captive pottos (Perodicticus potto). Pp. 30-35 in PRIMATE BEHAVIOR AND SOCIOBIOLOGY. A.B. Chiarelli, R.S. Corrucini, eds. Berlin, Springer Verlag, 1981. Deag, J.M. A STUDY OF THE SOCIAL BEHAVIOUR AND ECOLOGY OF THE WILD BARBARY MACAQUE Macucu syluanus L. PhD dissertation, University of Bristol, 1974. Deag, J.M.; Crook, J.H. Social behavior and “agonistic buffering” in the wild Barbary macaque, Macaca sylvanus. FOLIA PRIMATOLOGICA 15:183-200, 1971. De Turckheim, G.; Merz, E. Breeding Barbary macaques in outdoor enclosures. Pp. 241-261 in THE BARBARY MACAQUE: A CASE STUDY IN CONSERVATION. J.E. Fa, ed. Plenum Press, New York, 1984. Dunbar, R.I.M.; Nathan, M.F. Social organisation of the Guinea baboon (Papiopupio). FOLIA PRIMATOLOGICA 17:321-334, 1972. Eisenberg, J.F.; Muckenhirn, N.A.; Rudran, R. The relation between ecology and social structure in primates. SCIENCE 176:863874, 1972. Gautier-Hion, A. L’organisation sociale d‘une bande de Talapoins (Miopithecus tulupoin) dans le nord-est du Gabon. FOLIA PRIMATOLOGICA 12:116-141, 1970. Hammerschmidt, K. INDIVIDUELLE LAUTMUSTER BE1 BERBERAFFEN (Macaca sylvanus): EIN ANSATZ ZUM VERSTANDNIS IHRERVOKALEN KOMMUNIKATION: Dissertation, Freie Universitat Berlin, Germany, 1990. Hammerschmidt, K.; Ansorge, V. A birth of a Barbary macaque. FOLIA PRIMATOLOGICA 52:78-87,1989. Kummer, H. SOCIAL ORGANISATION OF THE HAMADRYAS BABOON. Basel, Karger, 1968. Kuster, J., Paul, A. Female reproductive characteristics in semifree-ranging Barbary macaques (Macuca sylvanus). FOLIA PRIMATOLOGICA 43:69-83, 1984. Kuster, J.; Paul, A. Male infant relationships in semi-free ranging Barbary macaques (Macaca syluanus) of Affenberg SaledFRG; testing the male care hypothesis. AMERICAN JOURNAL OF PRIMATOLOGY 10:315-327, 1986. Lehmann, J. AKUSTISCHE PARAMETER WEIBLICHER BERBERAFFEN (MACACA SYLVANUS) IM KONTEXT DES PAARUNGSVERHALTENS. Diplom-thesis, FB Biologie, Freie Universitat Berlin, Germany, 1989. McGuire, M.T.; et al. THE ST. KITTS VERVETS. Basel, Karger, 1974. Paul. A. ZUR SOZIALSTRUKTUR UND 280 I Ansorge et al. SOZIALISATION SEMI-FREILEBENDER BERBERAFFEN (MACACA SYLVANUS L. 17581, Dissertation, Universitat Kiel, Germany, 1984. Ransom, T.W. BEACH TROOP OF THE GOMBE. Lewisburg, PA, Bucknell University Press, 1981. Rasmussen, D.R. Correlates of patterns of range use of a troop of Yellow baboons (Papzo cynecephalus). 1.Sleeping sites, impregnable females, births, and male emigrations and immigrations. ANIMAL BEHAVIOUR 27:1098-1112, 1979. Riss, D.; Goodall, J. Sleeping behavior and associations in a group of captive chimpanzees. FOLIA PRIMATOLOGICA 251-11, 1976. Small, M.F. Alloparental behavior in Barbary macaques, Macaca sylvanus. ANIMAL BEHAVIOUR 39:297-306,1990a. Small, M.F. Promiscuity in Barbary macaques. AMERICAN JOURNAL OF PRIMATOLOGY in press, 1990b. Steuckardt, A. Family size and social network of female Barbary macaques (Macacu sylvanus). Poster Presentation, 1ST. CONGRESS OF THE GESSELLSCHAFT FUR PRIMATOLOGIE e.V., Giittingen, Germany, 1989. Taub, D.M. ASPECTS OF THE BIOLOGY OF THE WILD BARBARY MACAQUE (PRIMATES CERCOPITHECINAE, MACACA SYLVANUS L. 1758): BIOGEOGRAPHY, THE MATING SYSTEM AND MALE-INFANT ASSOCIATIONS. PhD dissertation, University of California, Davis, USA, 1978. Taub, D.M. Male care-taking behavior among wild Barbary macaques (Macaca sylvanus). Pp. 20-55 in PRIMATE PATERNALISM. D.M. Taub, ed. New York, Van Nostrand Reinhold Co., 1984. Timme, A. DIFFERENTIELLE AUFZUCHTSTRATEGIEN SEMI-FREILEBENDER (MACACA BERBERAFFENMUTTER SYLVANUS, L. 1758) IN ABHAN- GIGKEIT VOM MUTTERLICHEN RANG UND DEM GESCHLECHT DES INFANTES. Dissertation, Georg-AugustUniversitat Gottingen, Germany, 1989. Todt, D.; Bruser, E.; Hultsch, H.; Lange, R. Nocturnal actions and interactions of newborn monkeys. JOURNAL OF HUMAN EVOLUTION 11:383-389,1982. Todt, D.; Gross, H.; Hammerschmidt, K.; Ziihlke, K. Performance characters and significance of the dusk chorus in the Barbary macaque (M.sylvanus). INTERNATIONAL JOURNAL OF PRIMATOLOGY 47:665, 1984. Todt, D.; Pohl, R. Communicative strategies in estrous barbary ape females (M.syluanus) during copulation behaviour: Advertising, triggering, affiliating. VERH. DTSCH. ZOOL. GES. 77:225,1985. van den Bergh, U. PAARUNGSVERHALTEN VON BERBERAFFEN (M. SYLVANUS): ANALYSE EINSELNER VERHALTENSPARAMETER IM PAARUNGSABLAUF. Diplomthesis, FB Biologie, Freie Universitat Berlin, Germany, 1989. Vessey, S.H. Night observations of freeranging rhesus monkeys. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 38:613-620,1973. Wolff, A. Zum bioakustischen Verhaltensrepertoire neugeborener Berberaffen (M. sylvanus), mit Bezug auf den situativen Kontext. Diplomthesis, FU-Berlin, Germany, 1985. Wolff, A.; Todt, D. The Effect of vocal signals performed by newborn monkeys ( M . sylvanus) on Infant Caretaker Distance. VERHANDLUNGEN DER DEUTSCHEN ZOOLOGISCHEN GESELLSCHAFT 78:219, 1985. Wrangham, R. Social relationships in comparative perspective. Pp. 325-335 in PRIMATE SOCIAL RELATIONSHIPS. R.A. Hinde, ed. Oxford, England, Blackwell Scientific Publications, 1983.