American Journal of Primatology 29:49-59 (1993) BRIEF REPORTS Behavioral Contrasts Between Male Cynomolgus and Lion-Tailed Macaques A. S.CLARKE* AND D. G. LINDBURG Center for the Reproduction of Endangered Species, Zoological Society of San Diego, San Diego, California Evidence indicates that primate species differ not only in social structure and concordant social propensities, but also in their approach toward novel objects, environments, and procedures. These differences in response dispositions have been described as being based on differences in characteristic stances toward the environment, also called temperaments. This report extends previous comparative primate research by describing behavioral contrasts observed among males of two macaque species, liontailed and cynomolgus macaques. The lion-tails demonstrated more interest in other animals, more vigilance and instrumental behavior, and more readily adapted t o training to enter a small and unfamilar cage than the cynomolgus. These results suggest temperamental differences between the two species. Lion-tails may be characterized as bold, curious, and instrumental in their approach to the environment, while cynomolgus may be characterized as more passive or "reserved." These differences may form the basis for the well-developed sensorimotor abilities observed in liontails such as the manufacture and use of tools, and may also be related t o their highly omnivorous diet. o 1993 Wiley-Liss, Inc. Key words: species differences, temperament, manipulative behavior, sensorimotor ability, Macaca silenus, Macaca fascicularis INTRODUCTION Evidence is accumulating that closely related primate species show differences in proclivities toward engaging in certain types of behaviors, even where behavioral repertoires are highly similar [Clarke & Mason, 1988;Mason et al., in press]. Given the variety of social structures observed within the primate order, such differences might be expected to be most apparent under social conditions. Indeed, a number of studies have found distinct contrasts among primate species under various social conditions or social challenges [e.g., Anzenberger et al., 1986; Caine & Mitchell, 1980; Cubicciotti & Mason, 1975; Cubicciotti et al., 1986; Davis et al., 1968; Hawkes, 1970; Mason et al.,in press; Mendoza & Mason, 1986; Small, 19821. Similarly, other comparative primate studies have noted differences in nonsocial activity profiles, such as use of space, foraging patterns, and time spent in loco- Received for publication March 10, 1992; revision accepted July 10, 1992. Address reprint requests to A.S. Clarke, Harlow Primate Laboratory, University of Wisconsin, 22 North Charter Street, Madison, WI 53715. 0 1993 Wiley-Liss, Inc. 50 / Clarke and Lindburg motion, vigilance, self-directed behavior, etc. [Andrews, 1984; Caine et al., 1981; Davis et al., 1968; Fragaszy & Mason, 1983; Kawata, 19801. Some of these differences have been related to dietary and habitat differences in the wild [Caldecott, 1986; Fragaszy & Mason, 1978, 1983; Glickman & Sroges, 1966; Parker, 19741. While responses to the nonsocial environment might be predicted to show less obvious contrasts between species, several studies have noted behavioral differences among primate species in nonsocial test situations. The most common of these have involved responses to novel objects. In the largest study, Torigoe  compared object manipulation among 74 primate species. He found a large range of interspecific variation in degree and complexity of object manipulation, with the apes, Cebus species, and macaques the most manipulative. Similarly, Parker  compared ten primate species in degree of object manipulation and found that great apes showed the most frequent and diverse manipulative actions. Other studies have sought to characterize differences among primates toward novel stimuli beyond simply the degree of exploratory or manipulative behavior exhibited. Glickman & Sroges 119663 compared novel object responses among 24 primate species and found that baboons and macaques were the most responsive and were characterized as “highly reactive,” “aggressive,” and “vigorous” in their approach toward the objects. Singh & Manocha 119661 found contrasts between langurs (Presbytis entellus) and rhesus monkeys (M. muluttu) in their responses to a variety of objects. Langurs were more bold and less fearful than rhesus, approached and contacted the objects more often, and showed less abnormal behavior. Rhesus were also found to differ from gibbons (Hylobutes lur and H . pileatus) in response to novel stimuli. Gibbons were more active, manipulative, and bold in their approach toward unfamiliar objects, animals, and environments, while rhesus showed more disturbance behavior [Bernstein et al., 19631. These species differences have been characterized as response dispositions or temperaments [Higley & Suomi, 1989; Kagan, 1989; Mason et al., in press; Mendoza & Mason, 19891, which may be described in relation to stimuli as attributes such as “habituation, persistence, boldness and distractability” [Cubicciotti et al., 19861. For example, in comparisons of two New World species, squirrel (Suimiri sciureus) and titi monkeys (Cullicebus rnolloch) in response to various challenges, Suimiri were characterized as more active, more “opportunistic,” “impulsive,” and ‘%older”than Cullicebus [Mendoza & Mason, 1984,19861.A recent report comparing responses of a New and an Old World species (Cebus upellu and M.fasciculuris) to a highly salient artificial stimulus (a snake model) also illustrates temperamental differences in responses to this provocative stimulus. The cebus monkeys engaged in more approaches, exploratory behavior, and contact with the snake model than the macaques, whose behavior toward the model was characterized by avoidance and fearful behavior. The authors suggested that these differences were based on contrasts in predator defense and foraging strategies in the wild, which were in turn related to the temperaments of the two species [Vitale et al., 19911. Among the genus Mucacu, only a few species are well studied, and the number of directly comparative studies is limited. While superficially similar in social structure, these congeneric species do exhibit differences in aspects of social and sexual behavior [reviewed in Melnick & Pearl, 1987; Shively et al., 19821. In a series of laboratory studies, females of three macaque species (M.rnuluttu, M. mdiutu, and M . fusciculuris) were compared in their psychophysiological responses to several novel situations. The species showed striking contrasts in behavioral and physiological responses to a novel environment [Clarke et al., 1988al and to a simple operant training task [Clarke et al., 1988bl. In both situations, M. muluttu were characterized as the most active and instrumental in their approach toward Male Macaque Behavior / 51 the situations, M.radiuta as the most passive and least disturbed, and M. fascicularis as most disturbed. These differences were interpreted as based on temperamental factors that contrasted between the species [Clarke et al., 1988a,b]. Here we describe behavioral contrasts observed between males of two macaque species, lion-tailed macaques (M. silenus) and cynomolgus macaques (M. fascicularis), while housed individually and in response to a simple operant training task. Cynomolgus are relatively well known, but there have been few studies of the endangered lion-tailed macaque. Both species are arboreal, omnivorous, nonseasonally breeding, and live in mixed agehex groups. Cynomolgus occupy a wide variety of habitats throughout Asia [Richard et al., 19891. Lion-tails appear to be restricted to primary forest [Green & Minkowski, 1977; Johnson, 19851, although their now-limited range and endangered status make it diffieult to assess the possible diversity of their true natural habitats [Vijayan, 19851. METHODS Subjects The subjects were five adult male cynomolgus macaques (Macaca fmcicularis) and five adult male lion-tailed macaques (M. silenus). Ages ranged from 10-15 yrs for the cynomolgus and 7-14 yrs for the lion-tails. All monkeys were believed to be captive-born. The animals were housed in identical individual outdoor run cages (2 x 3 x 4m) in an off-exhibit facility at the Zoological Society of San Diego. The animals were housed such that individuals of each species were in adjacent cages with opaque side walls and the groups were directly across from each other. Thus, conspecifics could not see each other, but each had direct visual access from the front of cage to a member of the other species opposite (approximately 1.5 m apart, separated by a walkway). All of the animals also had limited visual contact with a large group of lion-tailed macaques housed nearby. Wire sitting platforms (perches) were located at approximately one-half the cage height at the rear of each cage. The front of the cages were equipped with a plastic shelter box (1 x 1 x 1.5m) that could be entered from a side door. The shelter box was mounted approximately 3 m off the floor, and the top of the box thus provided the most elevated perch in the cage. The cages were roofed, and the floors were covered with hay. Hay was changed and the cages cleaned on a weekly basis. The animals were fed h i t s , vegetables, and commercial primate biscuits daily, and had water available ad libitum. Procedures Undisturbed condition. Behavioral data were collected from the subjects in their individual run cages by the first author from a distance of 1m from the cage front. Behaviors measured included locomotion, vocalization, feeding, foraging in the hay substrate, environmental exploration, self-grooming, vigilance [defined as being at the cage mesh with gaze directed outward, Caine et al., 19811, and facial displays directed at animals caged nearby or the observer (threats, lipsmacks, bared-teeth displays, and yawns). In addition, use of space and structures within the cage was recorded. Stationary use of three locations (sitting or standing on> was recorded: on top of the nest box at the front of the cage (a location providing the best view of other animals); on the elevated perch at the rear of the cage (from which no animals were visible); or, on the floor (where some animals might be visible, depending on the subject’s location on the floor). Behavioral data were collected between 9:OO-11:OO AM for 20 min per subject, 3 days a week for 5 weeks. Within species groups, behavioral data from individuals were collected in preas- 52 / Clarke and Lindburg signed random order. Testing order and times were balanced across species groups. Behavioral data were recorded via one-zero sampling [Altmann, 19741,using 20 sec intervals. Portable cage entry training. In this condition, the subjects were trained to enter a portable metabolism cage voluntarily from their home cages, in order to later collect urine samples for hormonal analysis as part of another study. During training trials, the portable cage was attached by clips and chains to the wire mesh of the subject’shome cage, and both cage doors opened. The subject was given 3 min in which to enter the cage. If the monkey entered within the 3 min period, the latency to enter (timed by stopwatch to the nearest second) was recorded. The monkey then received a food reward and was confined in the cage for 5 min. If a monkey did not enter within the 3 min interval, the cage doors were closed and the trial was terminated. All subjects received five trials per day, one trial at a time, with subjects tested in random order. Criterion for successful training was considered to be five consecutive voluntary entries within the three-minute interval [Clarke et al., 1988bl. All subjects received 50 training trials, although all subjects met criterion at between 30-45 trials. The ability to view group-housed lion-tails (including females) not visible from their home cages but easily viewed from the metabolism cages also provided a social incentive for entering the portable cages. Data collected on training performance allowed for comparison of the two species in their responses to these procedures. Data Analysis Interspecific comparisons of behavioral measures were made by MannWhitney U tests. Comparison of cage training latencies was made by an independent t test. The distribution of cage entries vs. refusals among the two groups was evaluated by a Fisher’s exact test. RESULTS Three behaviors differed substantially between the two species in the solitary condition. Lion-tails engaged in significantly more vigilance behavior (looking out of the cage) than the cynomolgus (Fig. l A , U = 3.0,P = .04).Lion-tails also foraged in the hay substrate more frequently that the cynomolgus(Fig. lB,U = 0,P = .009). In contrast, the cynomolgus monkeys self-groomed more frequently than the liontails (Fig. lC, U = 3.0,P = .04).The two groups also differed in utilization of locations within the cage, showing symmetrically opposite patterns in use of the two arboreal cage structures. Lion-tails were observed significantly more often than cynomolgus on top of the shelter box (U= 2.0, P = .03),whereas cynomolgus spent significantly more time than lion-tails on the elevated perch W = O , P=.OO9). These data are shown in Figure 2. There was no difference between the groups in time spent on the floor. There were also no significant differences for the other solitary behaviors recorded (locomotion,vocalization, feeding, and environmental exploration), nor in facial displays directed at nearby animals or the observer. In the cage training condition, the two species showed consistent differences in performance on the task of voluntarily entering the portable cage within the required interval. .As shown in Figure 3, average latency to enter was consistently longer for the cynomolgus over all training trials (t = 6.1, P=.OOl). A second measure of training performance, the number of refusals to enter vs. voluntary entries, was also greater for the cynomolgus (P=.03,Fisher’s test). This result is shown in percentage form in Figure 4. Male Macaque Behavior I 53 ‘OW 1 I H LTM m VIGILANCE 8o 1 B 2o 1 HAY FORAGE SELF-GROOM Fig. 1. Mean frequency of display of the behaviors (A)vigilance, (B)foraging in the hay substrate, and (C) self-grooming in male lion-tailed (LTM) and cynornolgus (CYN) macaques. 54 / Clarke and Lindburg LTM CYN -r 40 Z W 3 30 CI W K 20 LL 10 0 SHELTER BOX PERCH Fig. 2. Mean frequency of sitting or standing on the elevated structures in the cage, perch and shelter box. iz +. A -- E 0’ LTM CYN I I I I I I I I I I 5 10 15 20 25 30 35 40 45 50 TRIALS Fig. 3. Mean latency to voluntarily enter a portable metabolism cage over 50 training trials. DISCUSSION Several striking behavioral contrasts between the lion-tail and cynomolgus groups were demonstrated under these conditions. Lion-tails engaged in much more frequent vigilance and manipulation of the hay substrate than the cynomolgus. In contrast, the cynomolgus showed more frequent self-grooming behavior. The lion-tails also entered the initially novel metabolism cage more often and consistently more quickly than the cynomolgus during training. While in the metabolism cages, all animals could view animals not visible from within their single cages, including two lion-tail groups containing females and young. This may have provided a social incentive for entering the smaller cages [Fujita, 19871. The liontails’ performance during training suggests a more active approach and greater “boldness’’ toward unfamiliar aspects of the environment for this species, and perhaps a greater general interest in the outside environment and/or other animals. Differences between macaque species in an analogous procedure were also interpreted as the result of interspecific differences in temperaments rather than in learning ability [Clarke et al., 1988bl.Other comparative studies of learning in Male Macaque Behavior / 55 loo 3 5 1 LTM 8o 60 40 8 20 0 REFUSALS TO ENTER Fig. 4. Mean percent of trials in which animals refused to enter the portable metabolism cage within the 3 min trial interval. macaques have generated similar conclusions [Schrier, 1965; Symmes & Anderson, 19671. All of these results suggest that the lion-tails were more oriented towards external objects and events in their environment, and were the more “instrumental” of the two species. Manual manipulation of the hay substrate and vigilance are both forms of environmental exploration, although one is tactile and the other visual. Other data suggest that lion-tails are a highly manipulative and instrumental species, perhaps more so than other macaques [Westergaard, 19881. In a previous study, lion-tails were found to be the most manipulative and exploratory of 13 macaque species, and to use the greatest variety of manipulations of objects [Torigoe, 19871. M. fusciculuris were ranked fourth in both frequency and variety of object manipulation in the same study. Taken together, these behavioral tendencies suggest a greater “curiosity” toward the environment [Wood-Gush& Vestergaard, 19911 for the lion-tails than for the cynomolgus. This tendency has been related to an omnivorous diet [Westergaard, 1988; Wood-Gush & Vestergaard, 19911, which in turn depends on welldeveloped exploratory behavior and a tendency to exploit foods which are embedded or otherwise require manipulation for acquisition [Gibson, 1986; Parker, 1973; Parker & Gibson, 19771. Thus, lion-tails might be expected to be more omnivorous and/or to make greater use of extractive foraging techniques in the wild. Data indicate that lion-tails are highly omnivorous [Artaud, 1980; Johnson, 1985; Green, 19761, probably more so than the more frugivorous cynomolgus [Wheatley, 19801. Whether lion-tails also utilize more manipulative and/or extractive foraging techniques than cynomolgus is uncertain. However, the hay foraging data suggest this, a8 do other data indicating advanced sensorimotor abilities [Torigoe, 1987; Westergaard & Lindquist, 19871, and well-developedtool use in this species [Westergaard, 19881. Tool use has been linked to the use of extractive foraging techniques, since most animal tool use occurs in this context [Beck, 1990; Parker & Gibson, 19771. Lion-tails have been observed to use tools in food preparation in the wild [Hohmann, 19881 and for food acquisition in captivity [Westergaard, 19881. Further, this is the only Old World monkey species in which a group of animals has been observed to spontaneously manufacture and use tools [Westergaard, 19881. The two species also differed in their use of space and structures: lion-tails spent most of their time on the shelter box (the most arboreal cage structure), 56 / Clarke and Lindburg while cynomolgus preferred the midlevel perch. While other animals could be viewed from the top of the shelter box, none were visible from the perch. It is unclear as to whether this result reflected a difference in height preference per se or in the desire to view other animals. Both species are primarily arboreal, however, lion-tails are believed to be the most arboreal macaque species [Roonwol & Mohnot, 19771. It is likely that the lion-tails preference for the shelter box reflected both their greater general vigilance tendency, and apparently greater motivation to view other animals. That the species did not differ in time spent on the floor supports this interpretation. Other data from studies of multimale and onemale captive groups indicate that lion-tail males in these groupings also spend a large proportion of their time in vigilant behavior, whereas group-living cynomolgus do not [Clarke, Harvey, & Lindburg, unpublished data). Other studies have also found variation among macaques in vigilance. Davis et al. [19681 found that rhesus engaged in considerably more vigilance than pigarctoides). Caine et al. [19811 found that tails (M.nemestrinu) or stumptails (M. rhesus showed much more vigilant behavior than bonnets (M. radiata). This difference was ascribed to the fact that rhesus are the more aggressive, show less interindividual tolerance, and are more likely to emmigrate. Thus, rhesus were more often peripheral and vigilant, while bonnets directed their attention into their more social groups. A similar explanation may account for these results. Lion-tails show little or no intermale tolerance in captive groups and high levels of agonism. In contrast, these cynomolgus macaques showed frequent ailiative behavior and low levels of aggression in social contexts. The greater self-grooming exhibited by the cynomolgus may be related to their greater frequency of allogrooming in a group (Clarke & Lindburg, 1988 and unpublished data). It is likely that the behavioral propensities found to differ between these two species are based on more broad and general temperamental differences between them. These observations may also be related to social, dietary andlor habitat differences, which in turn may be based on phylogenetic divergence [Fooden, 19801. Probably all of these contribute to the species differences reported here in response to objects and features of the physical environment. Available evidence suggests that the lion-tailed macaque is unique among macaques in its welldeveloped instrumental and tool-using activity. The display of these abilities is likely facilitated by the lion-tails’ bold and active approach toward novel aspects of the environment. CONCLUSIONS 1. These data extend previous comparative studies of macaques and demonstrate that males of two species differed dramatically in several aspects of behavior. 2. The behavioral differences observed appear to be based on temperamental differences between the species in response to environmental stimuli. Lion-tails may be characterized as bold and instrumental in their approach to nonsocial stimuli, whereas cynomolgus are more passive and reserved. 3. Lion-tails appear to have the most advanced sensorimotor abilities of macaques studied thus far, and these abilities are likely enhanced by their bold and curious nature. ACKNOWLEDGMENTS We thank N. Harvey, D. Forster, and J. Malone for assistance in cage training, and S. Mitchell for manuscript preparation. The research was supported in part by Male Macaque Behavior / 57 NIH grant RR05481 to A. S. Clarke and D. G. Lindburg. Assistance was provided by the staff and resources of the Wisconsin Regional Primate Research Center library, which is supported by PHS grant RRO169-32.Portions of the manuscript were prepared while A. S. Clarke was supported by the John D. and Catherine T. 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