Polyspecific associations of <Emphasis Type="Italic">Cercopithecus campbelli</Emphasis> and <Emphasis Type="Italic">C. petaurista</Emphasis> with <Emphasis Type="Italic">C. diana</Emphasis>: what are the costs and benefits?

Polyspecific associations (PSA) are common in many African primate communities, including the diurnal primates at Taï Forest, Côte d’Ivoire. In this paper I use data on the PSA of two forest guenons, Campbell’s (Cercopithecus campbelli) and lesser spot-nosed monkeys (C. petaurista), with Diana monkeys (C. diana) and other primates to clarify interspecific relationships during 17 months including a 3-month low-fruit period. I analyzed association in relation to fruit availability and measured forest strata use for C. campbelli and C. petaurista when alone and in associations with and without C. diana. I also measured predator risk and reactions to potential predators. C. campbelli and C. petaurista had high association rates with C. diana monkeys, and fruit availability did not influence association rates. C. campbelli and C. petaurista used higher strata when in association with C. diana than when alone, but they used even higher strata when associated with other primates without C. diana. This suggested that C. diana competitively exclude C. campbelli and C. petaurista from higher strata. There were relatively large numbers of potential predators, and C. diana were usually the first callers to threatening stimuli, suggesting that antipredator benefits of association with C. diana outweighed the competitive costs. C. campbelli spent more time in association with C. diana than C. petaurista did and appeared to be more reliant on C. diana for antipredator benefits. C. petaurista were less reliant on C. diana because of a cryptic strategy and may have associated less in some months because of high chimpanzee (Pan troglodytes) presence.     

The differential use of cheek pouches in a troop ofPapio ursinus

Cheek pouches, one of the distinguishing characters of the Cercopithecinae, are structures used for the temporary storage of food. Their size and frequency of use within a given species are related primarily to the amount of conspecific competition for food. In relation to total body size, members of the genusPapio are considered to have relatively small cheek pouches which are said to be used only occasionally to maximize food harvest when local clusters of food are encountered. This investigation represents 165 hours of observation on a troop ofPapio ursinus at Mkuzi Game Reserve in Natal, South Africa. At the time of observation the choice of foods in the home range was restricted and usually found in abundance only in small clusters of trees. Given that conspecific competition would have been pronounced under these conditions, it was thought that any differences in the frequency of cheek pouch use related to age, sex, rank, or the reproductive state of an animal would be readily recognizable. The results indicated that cheek pouches were used differentially throughout the day, with virtually all ages of each sex displaying the same general pattern of maximal cheek pouch use during the middle of the day. In each sex there was an age graded diminution of the frequency of cheek pouch use from juveniles to adults. This trend was more pronounced in males resulting in a substantial sex difference in the use of cheek pouches between adult males and females. In addition, there was some indication that differences in the frequency of cheek pouch use between adult males were correlated with rank. Although a pattern of cheek pouch use and rank was not evident amongst adult females, there was an association between reproductive state and the frequency of cheek pouch use. Overall, body size, dominance, and energetic demands appeared to be the most significant factors underlying the differences in cheek pouch use in this troop.     

Cheek pouch use, predation risk, and feeding competition in blue monkeys (Cercopithecus mitis stuhlmanni)

The adaptive function of cheek pouches in the primate subfamily Cercopithecinae remains unresolved. By analyzing the circumstances of cheek pouch use, we tested two hypotheses for the evolution of cercopithecine cheek pouches proposed in earlier studies: (1) cheek pouches reduce vulnerability to predation, and (2) cheek pouches increase feeding efficiency by reducing competition. We studied two groups of wild blue monkeys (Cercopithecus mitis stuhlmanni) in the Kakamega Forest, Kenya, conducting focal observations of feeding individuals. Monkeys were less exposed while emptying their cheek pouches than filling them, supporting the predation-avoidance hypothesis. We investigated several measures of competitive threat, but only one supported the competition-reduction hypothesis: when the nearest neighbor's rank increased, subjects were more likely to increase than to decrease cheek pouch use. Overall, our findings supported the predation-avoidance hypothesis more strongly than the competition-reduction hypothesis. We suggest that variation in cheek pouch use may reflect differing behavioral strategies used by cercopithecines to mitigate competition and predation, as well as factors such as resource size and distribution, home range size, and travel patterns.     

Positional Behavior of Cercopithecus petaurista

I studied the positional behavior and habitat use of Cercopithecus petaurista, the lesser spot-nosed monkey, in the Ivory Coast's Taï Forest for 15 months. I compare these data with similar information collected on sympatric groups of Cercopithecus diana and C. campbelli in order to examine further the relationships between locomotion, posture, support use, stratal use, body size, diet, activity patterns and foraging behavior. Spot-nosed monkeys are predominantly quadrupedal primates that frequent the top layer of the understory during all maintenance activities. Locomotion is characteristically slow and cautious; travel takes place on branches and boughs while foraging occurs on twigs and branches. Postural behavior of Cercopithecus petaurista reflects their reliance on more ubiquitously distributed, less mobile food items. The relationship between body size, climbing, leaping and support use among Taï guenons is weak; interspecific differences are more likely functions of strata use and overall behavioral characteristics, e.g. crypticity. I also compare the locomotion and support use of Cercopithecus petaurista with that of C. ascanius from Uganda's Kibale Forest (Gebo and Chapman, 1995a) in order to assess the behavioral similarity of members of the same superspecies. Although overall support use is quite similar, the monkeys differ significantly in frequencies of quadrupedism, leaping and climbing. I present possible reasons for and implications of these differences.     

一例恒河猴颊囊鳞状细胞癌的病理学观察

通过对一例恒河猴颊囊肿块临床症状表现、剖检肉眼观察及光学显微镜组织病理形态变化观察,发现该病猴颊囊病灶组织病变具有与人鳞状细胞癌相似的典型特征,确诊为颊囊鳞状细胞癌,可为判断非人灵长类动物肿瘤性疾病提供一定的病理诊断依据。     

Cheek pouch capacities and loading rates of heteromyid rodents

Rodents of the family Heteromyidae are proficient gatherers and hoarders of seeds. A major component of their adaptive specialization for harvesting and transporting seeds is their spacious, fur-lined cheek pouches. Precise measurements of cheek pouch capacities are essential if ecologists are to understand the foraging ecology, possible constraints on locomotion patterns, and competitive relationships of heteromyid rodents. To measure the size of these cheek pouches and the rate at which animals load seeds into their pouches during seed harvest, we attracted 56 individuals representing ten species of heteromyid rodents to bait stations in the field and allowed them to fill their cheek pouches with seeds several times while we observed and timed the events with the aid of night-vision equipment. The largest load taken by each individual was used as an estimate of its cheek pouch capacity. At the end of observations, each subject was captured and its mass and other data gathered. The allometric relationship between cheek pouch capacity and body mass for ten species of heteromyids was significant [pouch capacity (ml) = 0.148 body mass (g)^0.992, r ²=0.91, P<0.0001]. The regression coefficient is ≈1.0, which indicates that the volume of the cheek pouches scales in direct proportion to body size. When the data were subdivided into quadrupeds (Perognathus and Chaetodipus) and bipeds (Dipodomys) (n=5 for each), the relationships between pouch capacity and body mass were significant, but the two regressions were not significantly different from each other. When all loads (full and partial) were considered, subjects filled their cheek pouches an average of 93 ± 10% of pouch capacity (n=185). Cheek pouch capacities from published studies of artificially filled pouches of heteromyids in the laboratory averaged about 40% below the field measurements obtained here. The allometric relationship between mean loading rate and body mass was also significant [seeds/s=1.067 bodymass (g)^0.830, r ²=0.85,P=0.0011), but when quadrupeds and bipeds were considered separately, the relationships were not significant. Seed densities and bulk densities were used to calculate packing coefficients for seed species, which, when used in conjunction with the allometric relationship between cheek pouch capacity and body size, can be used to estimate the maximum load carried by a heteromyid. Except for the very largest kangaroo rat species, a full pouch load of Indian ricegrass seeds represents less than the daily energy requirements of an active heteromyid. Received: 3 March 1997 / Accepted: 15 July 1997     

Frequent insectivory by two guenons (Cercopithecus lhoesti and Cercopithecus mitis) in the Kalinzu Forest, Uganda

I investigated the feeding ecology of lHoests monkeys (Cercopithecus lhoesti) and blue monkeys (Cercopithecus mitis) in the Kalinzu Forest, Uganda. Although forest guenons are generally thought to be frugivores or folivores, these two guenons spent a large proportion of their time feeding on invertebrates. The lHoests monkey and the blue monkey spent as much as 66 and 50% of their time on insectivory, respectively. These proportions of time spent on invertebrate feeding are higher than those reported elsewhere for forest guenons. LHoests monkeys mainly utilized the area near the ground for invertebrate feeding, while blue monkeys utilized the area around 20 m above the ground. It seemed that guenons have an ability to change their diet according to the environment.     

Competition, predation, and the evolutionary significance of the cercopithecine cheek pouch: the case of Cercopithecus and Lophocebus

Reports of cercopithecine cheek pouch use and functional significance are largely anecdotal, and to date there have been no investigations into its use by species living in closed forest habitats. Here, I report on cheek pouch use in Cercopithecus ascanius and Lophocebus albigena in the Kibale National Park, Uganda, between July-October 1997. Two hypotheses were evaluated: this feature was selected for because of its role in 1) increasing feeding efficiency via a reduction in potential feeding competition, and/or 2) reducing vulnerability to predation. Results indicate that both species were more likely to use their cheek pouches when feeding on contestable foods and, after filling cheek pouches, retreated to more densely vegetated ("safer") positions for processing food. There was no influence of age and sex on L. albigena cheek pouch use. Subadult C. ascanius cheek-pouched less frequently than adults, although there were no differences between adult males and females. There was no relationship between feeding-patch size and number of plant food items cheek-pouched in either species. However, the diameter of breast height (dbh; a measure of patch size) of trees in which C. ascanius used their cheek pouches was significantly larger than the dbh of trees in which they did not. Both species were more likely to use their cheek pouches in the presence of greater numbers of conspecifics. These data provide insight into the relationship(s) among oral anatomy and feeding efficiency, and facilitate understanding into the selection for this important oral feature in stem cercopithecines.     

Foraging,Food Choice,and Food Processing by Sympatric Ripe-Fruit Specialists: <Emphasis Type="Italic">Lagothrix lagotricha poeppigii</Emphasis> and <Emphasis Type="Italic">Ateles belzebuth belzebuth</Emphasis>

Studies of interspecific competition and niche separation have formed some of the seminal works of ecology. I conducted an 18-mo study comparing the feeding ecologies of 2 sympatric, closely-related ripe-fruit specialists, Humboldt's woolly monkeys (Lagothrix lagotricha poeppigii), and the white-bellied spider monkeys (Ateles belzebuth belzebuth) in Amazonian Ecuador. Woolly monkeys in the terra firme forest live at roughly triple the density of spider monkeys (31 versus 11.5 animals/km²). Woolly monkeys spend 17% of their time foraging, while spider monkeys spend only 1% of their time foraging. Spider monkeys alone fed on soil and termitaria, which are rich in phosphorus. Woolly monkeys are not hard-fruit specialists. Their fruit diet is significantly more diverse than that of spider monkeys. Dietary overlap between the 2 species is high, yet each specializes to some degree on a different set of fruit resources. Woolly monkeys visit more food sources per unit of time, feed lower in the canopy, visit more small food patches, and prey on more seeds. Spider monkeys feed on fewer, richer food sources and are more than twice as likely to return to a particular fruit source than woolly monkeys are. Spider monkeys maximize fruit pulp intake, carrying more intact seeds in their guts, while woolly monkeys minimize seed bulk swallowed through more careful food processing. Surprisingly, several preferred spider monkey foods with high fat content and large seeds are avoided by woolly monkeys. I outline the different ecological dimensions involved in niche separation between the 2 species and discuss the possible impetus for their evolutionary divergence.     

Alternative seed-handling strategies in primates: seed-spitting by long-tailed macaques (Macaca fascicularis)

Summary The seeds in fruits consumed by primates may be chewed and digested, swallowed and defecated intact, or separated from the flesh and spat out. We show by a combination of close field observations and experiments with caged animals, that long-tailed macaques (Macaca fascicularis) have a remarkably low threshold of 3–4 mm for swallowing seeds and also that wild macaques rarely break them. The seeds of 69% of the ripe fruit species eaten are spat out intact or cleaned outside the mouth and dropped. Seed-spitting significantly reduces the swallowed food bulk and may lessen the risk of releasing seed toxins during mastication. However, it requires that even small fruits are processed in the mouth one or a few at a time. We suggest that fruit storage in the cheek pouches of cercopithecine monkeys allows them to spit seeds individually without excessively slowing fruit intake while feeding on patchily distributed fruit. In contrast, Apes and New World monkeys apparently swallow and defecate most ripe seeds in their diet and colobine monkeys break and digest them, detoxifying seed defenses by bacterial fermentation.     

Sexual dimorphism,mating system,and effect of phylogeny in De Brazza's monkey (Cercopithecus neglectus)

De Brazza's monkey (Cercopithecus neglectus), like other guenons, shows marked sexual dimorphism in an array of features. While strong sexual dimorphism is generally associated with a polygynous mating system, populations of De Brazza's monkeys in Gabon are reportedly monogamous. An explanation of this unique phenomenon is offered here. Patterns of sexual dimorphism are examined for morphology, growth and development, behavior, and ecology, and field and captive studies on the social organization and mating system of De Brazza's monkey and congeneric guenon species are reviewed. Based on the findings, it is postulated that 1) De Brazza's monkeys are not strictly monogamous, but exhibit interpopulational variation in their mating system, from facultative monogamy to mild polygyny; 2) marked sexual dimorphism most likely reflects the effect of the historical-phylogenetic factor; ie, it represents a holdover of a degree of dimorphism established earlier in evolutionary history when the degree of polygyny Was higher; and 3) lessening in the degree of polygyny and a tendency toward monogamy represents a consequence of selection toward small group size. Small group size, a unique antipredator strategy, and failure to form polyspecific associations are ultimately most likely the result of intragroup and interspecific competition and predation pressure.     

Red-Tailed Guenons (Cercopithecus ascanius) and Strychnos mitis: Evidence for Plant Benefits Beyond Seed Dispersal

I report data collected on red-tailed guenon (Cercopithecus ascanius schmidti) fruit processing behaviors between June 1993 and April 1994. Red-tailed guenons consumed the fruit of Strychnos mitis in 542 of 2,930 fruit-eating events (FEEs). The monkeys spat out cleaned seeds of Strychnos mitis in a majority of these records (477/542; 88%); seeds were occasionally swallowed whole, but only when pulp was unripe (69/542; 12%). In 83% of the FEEs on Strychnos, the red-tailed guenons spat out seeds within 10 m of the removal site; they typically stayed in the same tree while processing fruit, and in 56% of the FEEs, they moved <1 m before spitting seeds. I monitored spat seeds to evaluate the impact of monkey fruit processing on seed fate. Results indicate that 83% of seeds spat out by the red-tailed guenons germinated, while only 12% of unprocessed seeds survived to germination (p < 0.01). Of the processed seeds that germinated, 60% survived to germination and seedling establishment, while only 5% of unprocessed seeds survived to seedling establishment (p < 0.01). Unprocessed seeds were also more likely to be attacked by seed predators (p < 0.01) and fungus (p < 0.01). Although there is generally high mortality in seeds/seedlings, mature trees of Strychnos mitis are found in groves of adults, under which dense populations of seedlings and saplings can occur. These data suggest that Strychnos mitis does not conform to expectations of the Janzen-Connell model of seed escape from parent trees. Instead, I suggest that by removing pulp, a process that results in a reduction of fungal pathogen attack, red-tailed guenons positively effect the seed survivorship of Strychnos mitis. Although this effect has been observed in pulp-cleaning ant species, it is a hitherto undescribed effect of primates on their fruit resources.     

Cooperation and competition in two forest monkeys

Putty-nosed monkeys, Cercopithecus nictitans stampflii, occurat various sites in West Africa, particularly in the transitionzone between rainforest and savannah. The species is sometimesseen in primary rainforest, although at a curiously low densitycompared with that of other monkey species. We conducted a 24-monthfield study in the tropical rainforest of Taï NationalPark, Ivory Coast, and found that putty-nosed monkeys requirean ecological niche almost identical to that of the Diana monkeys,Cercopithecus diana diana. Moreover, the niche breadth of putty-nosedmonkeys was significantly decreased in the presence of Dianamonkeys, suggesting that feeding competition with Diana monkeyskept putty-nosed monkeys from successfully colonizing a rainforesthabitat. However, contrary to the interspecies competition hypothesis,groups of both species almost completely overlapped in homeranges and formed near-permanent mixed-species associations,rather than avoiding each other. We hypothesized that Dianamonkeys tolerated immigrating putty-nosed monkeys and formedmixed-species groups with them, despite high levels of competition,because of their merit in predation defense. Direct observationsand a series of field experiments confirmed that male putty-nosedmonkeys play a vital role in defense against crowned eagles,suggesting that putty-nosed monkeys obtain access to feedingtrees by offering antipredation benefits to Diana monkeys. Wediscuss these findings in light of biological market theory.     

How do frugivores track resources? Insights from spatial analyses of bird foraging in a tropical forest

Frugivores often track ripe fruit abundance closely across local areas despite the ephemeral and typically patchy distributions of this resource. We use spatial auto- and cross-correlation analyses to quantify spatial patterns of fruit abundance and avian frugivory across a 4-month period within a forested 4.05-ha study grid in Puerto Rico. Analyses focused on two tanager species, Spindalis portoricensis and Nesospingus speculiferus, and their principal food plants. Three broad questions are addressed: (1) at what spatial scales is fruit abundance and frugivory patchy; (2) at what spatial scales do frugivores respond to fruit abundance; and (3) to what extent do spatial patterns of frugivory overlap between bird species? Fruit patch size, species composition, and heterogeneity was variable among months, despite fruit patch locations remaining relatively consistent between months. Positive correlations between frugivory and fruit abundance suggested tanagers successfully tracked fruit abundance. Frugivory was, however, more localized than fruit abundance. Scales of spatial overlap in frugivory and monthly variation in the foraging locations of the two tanager species suggested that interspecific facilitation may have been important in determining bird foraging locations. In particular, S. portoricensis, a specialist frugivore, may have relied on the loud calls of the gregarious generalist, N. speculiferus, to find new foraging areas. Such a mechanism could help explain the formation of mixed species feeding flocks and highlights the potential importance of facilitation between species that share resources.     

Fruit removal rate depends on neighborhood fruit density,frugivore abundance,and spatial context

Fleshy-fruited plants depend fundamentally on interactions with frugivores for effective seed dispersal. Recent models of frugivory within spatially explicit networks make two general predictions regarding these interactions: rate of fruit removal increases (i.e., is facilitated) as densities of conspecific neighborhood fruits increase, and fruit removal rate varies positively with frugivore abundance. We conducted a field experiment that constitutes the first empirical and simultaneous test of these two primary predictions. We manipulated neighborhood abundances of arrowwood (Viburnum recognitum and Viburnum dentatum) fruits in southern New England’s maritime shrub community and monitored removal rates by autumn-migrating birds. Focal arrowwood plants in neighborhoods with high conspecific fruit density sustained moderately decreased fruit removal rates (i.e., competition) relative to those in low-density neighborhoods, a result that agrees with most field research to date but contrasts with theoretical expectation. We suggest the spatial contexts that favor competition (i.e., high-abundance neighborhoods and highly aggregated landscapes) are considerably more common than the relatively uniform, low-aggregation fruiting landscapes that promote facilitation. Patterns of arrowwood removal by avian frugivores generally varied positively with, and apparently in response to, seasonal changes in migratory frugivore abundance. However, we suggest that dense stands of arrowwood concentrated frugivore activity at the neighborhood scale, thus counteracting geographic patterns of frugivore abundance. Our results underscore the importance of considering spatial context (e.g., fruit distribution and aggregation, frugivory hubs) in plant-avian frugivore interactions.     

Association of Terrestrial Mangabeys (Cercocebus atys) with Arboreal Monkeys: Experimental Evidence for the Effects of Reduced Ground Predator Pressure on Habitat Use

We examined the behavior of two arboreal monkeys—Piliocolobus badius (western red colobus) and Cercopithecus diana (Diana monkey)—in the presence and absence of a third, predominately terrestrial monkey, Cercocebus atys (sooty mangabey) in the Ivory Coast's Taï Forest. Via experimental data, we show that sooty mangabeys are effective sentinels for ground predators. Then we compared strata use of red colobus and Diana monkeys in the presence and absence of mangabeys. Our data indicate that red colobus and Diana monkeys descend to low forest levels and to the forest floor significantly more often when mangabeys are spatially intermingled with them, i.e. in polyspecific associations. The niche extension may provide some foraging advantage, especially for red colobus. We identified the specific causal agent—relaxed ground predator pressure—of a temporary shift in habitat use. In this instance, the presence of one species (Cercocebus atys) leads to the temporary expansion of a niche normally avoided by others Piliocolobus badius and Cercopithecus diana.     

Ranging Patterns in Relation to Seasonality and Frugivory Among Cercopithecus campbelli, C. petaurista, and C. diana in the Taï Forest

My objective is to better understand the influences of seasonality and frugivory on ranging patterns for 3 guenon species of the Ta? Forest: Cercopithecus campbelli, C. petaurista, and C. diana). Over a 17-mo period, I gathered data on the daily path length, home range size, and home range use for 2 habituated groups of each species. The ranging patterns of the 3 species were very similar to each other and across seasons. Further, the ranging patterns were not closely related to fruit abundance or consumption. Each species had a long-ranging strategy with long daily ranges relative to home range size and little repeated use of areas on successive days, which may relate to territory and boundary patrols, especially for Cercopithecus diana. I compare them with other guenon communities and demonstrate that the ranging patterns of the 3 species are more similar than the ranging patterns of sympatric guenons in other communities. I discuss the results in relation to the association of Cercopithecus campbelli and C. petaurista with C. diana for antipredator benefits.     

Locomotion and habitat use of Stampflii's putty-nosed monkey (Cercopithecus nictitans stampflii) in the Taï National Park, Ivory Coast

Stampflii's putty-nosed monkeys Cercopithecus nictitans stampflii are large, rare, poorly known guenons with a discontinuous distribution in West Africa. Putty-nosed monkeys occur at low densities in Ivory Coast's Tai National Park where they are believed to have migrated from less forested regions north of the park (Eckardt and Zuberbühler: Behav Ecol 15 (2004) 400-411). In this article, we compare the positional behavior of Putty-nosed monkeys to that of three other guenon species in the Tai Forest and provide an additional test of the relationship among locomotion, body size, maintenance activity, and habitat use in generalized arboreal quadrupeds. Our results indicate that putty-nosed monkeys confine the great majority of their locomotion to the main canopy where most movement occurs on boughs and branches. Comparison of overall locomotor frequencies across the four Tai guenon species reveals a general pattern; quadrupedalism accounts for at least 70% of the total profile, climbing ranges between 15 and 20%, and leaping accounts for 5-10% of total movement. The overall locomotor consistency among the taxa, especially between putty-nosed and Diana monkeys, is significant considering marked interspecific differences in support preference and strata use.     

Referential labelling in Diana monkeys

Animal semantic communication has received considerable theoretical and empirical attention because of its relevance to human language. Advances have been made by studies of alarm-call behaviour in nonhumans. In monkeys, for example, there is evidence that recipients have a fairly sophisticated understanding of a call's meaning; that is, the predator type usually associated with a certain alarm call. Little is known, however, about the mental mechanisms that drive call production in nonhuman primates. In some nonprimate species, it has been found that signallers do not respond to a predator's physical features but instead seem to respond to its relative threat or direction of attack. In these species, therefore, alarm calls do not denote different predator categories but simply reflect different types or levels of danger. Because different predator categories typically impose different types and degrees of threat it is entirely possible that nonhuman primates also respond to threat rather than a predator's category. This study examined how wild Diana monkeys, Cercopithecus diana, of the Ta? forest, Ivory Coast, label predation events. By altering playback stimuli and the position of a concealed speaker, I investigated whether Diana monkeys respond with acoustically different alarm calls depending on a predator's (1) distance (close versus far), (2) elevation (above versus below), or (3) category (eagle versus leopard). Analysis of male and female alarm-call behaviour showed that Diana monkeys consistently responded to predator category regardless of immediate threat or direction of attack. Data further suggested that, in addition to predator category, monkeys' alarm calls might also convey information about the predator's distance. Copyright 2000 The Association for the Study of Animal Behaviour.     

Within-group differences in captive Diana monkey (Cercopithecus diana diana) behaviour

This case study examines the activity budgets of captive Diana monkeys (Cercopithecus diana diana) and discusses results in the context of what is known regarding captive and wild-type behaviour in this species and other guenons. The activities of a family group of Diana monkeys (two parents and four offspring) housed at Edinburgh Zoo, UK, were quantified using a 5-min interval scan sampling technique. The 5100 observation points collected showed that the subjects spent the largest proportion of their time observing (approx. 46%), followed by feeding (approx. 15%), playing (approx. 11%), mutual grooming (approx. 8%) and resting (approx. 7%). The daily activity budgets for each of the subjects were tallied and, at the end of the 10-day observation period, used to produce a data matrix consisting of nine behaviour variables per subject. Clear among-individual differences in activity were identified with canonical discriminant function analysis. This multivariate approach illustrated how the combined behaviours of the parent male were distinct from those of the rest of the family group. Within the remainder of the group, the three youngest offspring displayed similar activity budgets, whereas the overall behaviour of the eldest offspring (a female) was between that of its siblings and her mother.