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Capped langurs of Madhupur. Review of The Capped Langur in Bangladesh Behavioral Ecology and Reproductive Tactics by Craig B. Stanford. Basel Karger 1991 XVII + 179 pp 53 fig. 30 tab. 4 plates $98

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American Journal of Primatology 28299-302 (1992)
Capped Langurs of Madhupur
Review of The Capped Langur in Bangladesh: Behavioral Ecology and Reproductive
Tactics, by Craig B. Stanford. Basel, Karger, 1991, XVll
179 pp, 53 fig., 30 tab., 4
plates, $98.50, hardcover.
After over 30 years of field investigations, the behavioral ecology of a t least
one population has now been well-documented for many primate species. This has
provided a scattered but invaluable database on ranging behavior, activity budgets, dispersal patterns, and social behavior of individuals, from which synthetic
hypotheses in primate socioecology are being formulated. Early attempts to explain variation in primate behavior focused on classifying broad types of groupings
[e.g., Crook & Gartlan, 1966; Eisenberg et al., 19721. As more information has
become available, hypotheses have become more refined. More recent hypotheses
have addressed very specific issues, such as the nature of relationships between
individuals within and between groups [Wrangham, 1980; van Schaik, 1989; Isbell, 19911 and patterns of dispersal [Wrangham, 1980; Clutton-Brock, 19891. Testing these hypotheses necessitates renewed efforts to gather data on the behavior
and ecology of species not yet studied. We still have embarrassingly little data on
the natural history of forest primates, i.e., most New World monkeys, guenons, and
For this reason, Craig Stanford's study of the behavior and ecology of capped
langurs (Presbytis pzleata) is a helpful contribution to primatology. He collected
data in Madhupur National Park, Bangladesh over 15 months on various aspects
of their behavioral ecology, including ranging behavior (chapter 3 in the monograph), activity patterns (chapter 4), feeding ecology (chapter 5), and social behavior (chapters 6 and 7). The following is a brief summary of Stanford's findings:
capped langurs at Madhupur are leaf-eaters that also feed heavily on fruits a t
certain times of the year. They live in single-male, multi-female groups containing
about five adult females. Females have poorly defined dominance hierarchies
within groups because they rarely interact aggressively toward one another. The
main study group ranged over an area of about 22 hectares that overlapped extensively with the home ranges of other groups. Interactions between females of
different groups are non-aggressive. In contrast, resident males can be aggressive
toward males of other groups, particularly if those males are unfamiliar. During
intergroup encounters, the resident male typically places himself between his
group and other males, and acts aggressively toward females in his group if they
attempt to approach or appear to be attracted to other males. Males presumably
disperse from their natal groups at sexual maturity, and move about by themselves
Lynne A. Isbell is now at Department of Anthropology, Rutgers University, P.O. Box 270, Douglass
Campus, New Brunswick, NJ 08903.
0 1992 Wiley-Liss, Inc.
300 I Isbell
or in all-male bands. Females may also leave their natal groups but female dispersal appears to be less common than male dispersal.
The intent of this monograph was to provide a descriptive account of the
natural history of capped langurs and to incorporate this information into an
examination of some of the central issues and hypotheses in primate socioecology.
Unfortunately, the monograph was not carefully edited and it contains a large
number of errors that make it difficult to read. Some of the errors are sufficiently
serious that uncritical readers might be led to the wrong conclusions (e.g., in Fig.
5.10 it is stated that P > .05 when it is clear from the graphics that this is incorrect;
the text mentions a P value of < .001; also, Tables 5.3 and 5.4 are particularly
intriguing). Fortunately, some parts of the monograph have been published with
fewer errors and with arguments that he developed more clearly in peer-reviewed
journals. On the other hand, the monograph contains more discussion of the conceptual arguments, which I found interesting, even if sometimes difficult to follow.
Despite the editing (or lack thereof), the monograph addresses some of the
more fundamental issues in primate socioecology. Among these issues are the
functional significance of female transfer and the validity of Wrangham’s [19801
model of female-bonded vs. non-female-bonded primate species. When Stanford
went into the field in 1986, Wrangham’s was the only model that attempted to
explain the ecological determinants of variation in female relationships within and
between groups. As more studies are conducted, however, it is becoming clear that
there is more variation in female relationships than is accounted for by Wrangham’s model. Stanford is correct in recognizing this for his study species. He points
out that capped langurs are non-female-bondedin that females have poorly defined
dominance hierarchies within groups, they are not aggressive between groups, and
sometimes transfer to other groups. However, they also direct group movements, a
characteristic predicted for female-bonded species. In the last few years, newer
models [van Schaik, 1989; Isbell, 19911 have come into existence that do attempt
to account for this kind of variation, apparently after this monograph went to
press. It is still unclear just how much variation among primate species does exist,
and why, mainly because of the shortage of studies such as Stanford‘s on the
behavioral ecology of forest primates.
Stanford’s discussion of variation in female transfer is timely and informative.
He documented a t least three transfers of adult females into five study groups
during his 15 months of study. Accounting for variation in patterns of female
transfer is a relatively young issue in primate socioecology.Again, as more natural
history studies are conducted, it is becoming apparent that dispersal patterns are
more variable than previously believed. In many species, females typically remain
in their natal groups throughout their lives and only rarely transfer, e.g., most
macaques, baboons, and guenons [Pusey & Packer 19871. In other species, e.g.,
gorillas [Gorilla gorilla: Harcourt, 19781 and red colobus [Colobus badius: Struhsaker, 19751, females commonly transfer to other groups. In still other species,
female transfer is not common but does occur occasionally. Stanford is correct in
pointing out that female transfer is a puzzle in capped langurs. Unlike red colobus,
in which only females typically leave their natal groups, both male and female
capped langurs leave. In species such as capped langurs, in which both sexes
emigrate, it becomes more difficult to explain female transfer as a way to avoid
inbreeding. Stanford suggests that females may assess their opportunities for successful reproduction both in their current group and in other groups and leave
when better opportunities arise [see also Harcourt, 1978; Marsh, 19791.
What determines whether a female will remain in or leave her natal group?
Stanford was not able to determine exactly what females might be assessing.
Capped Langurs I 301
Wrangham [19801 suggested that females would remain when they benefit from
cooperation with relatives in defense of food resources. However, given that movement out of natal groups or natal home ranges entails known costs [Johnson &
Gaines 19901, we might expect females to remain philopatric regardless of the
positive benefits of remaining philopatric.
Dispersal is likely to be costly when animals either disperse into an unfamiliar
home range (locational dispersal), or interact with unfriendly, unfamiliar conspecifics (social dispersal), or both. The decision to disperse or stay will probably
depend on the number of potential costs that are faced by each individual, weighed
against the potential benefits. In most primate species, the cost of aggression from
unfamiliar neighbors appears to be sufficient to prevent most females from transferring into new groups. The capped langurs of Madhupur are an example of
species in which there is no female aggression and female transfer does occur a t
least occasionally, in common with several other colobine species. There are also
species in which groups of females are aggressive toward one another and females
nonetheless still occasionally transfer. This suggests that other costs prevent such
females from leaving their natal groups. The most obvious cost is that of moving
into an unfamiliar area. Female transfer tends to occur at low levels in more
species with extensive (as opposed to minimal) home range overlap. In fact, those
species in which female transfer occurs occasionally despite intergroup aggression
often have extensive home range overlap in which one might expect greater familiarity with the home ranges of new groups Ce.g., brown capuchins, Cebus apella:
Robinson & Janson 1987; rhesus macaques, Mucuca mulatta: Hausfater 19721.
Because, as Stanford shows, female capped langurs are not aggressive toward one
another and have extensive home range overlap, they may not suffer either social
or locational costs of dispersal.
The distinction between dispersal into an unfamiliar area and dispersal into
an unfamiliar social environment has not been made explicitly in the literature,
and should be helpful for understanding variation in female dispersal patterns
among primates. Because dispersal in group-living animals may include any combination of social and locational dispersal, group-living animals may face different
combinations of costs based on their particular situations. Stanford's study provides a good example of a system that would benefit from such analysis. Indeed,
with transfer occurring a t least occasionally, most langurs (Hanuman langurs, P.
e n t e l h , are an exception) should be an ideal group of species with which to compare the situations faced by those who disperse and those who stay behind.
At close to $100.00, this monograph is more likely to be found in libraries than
on personal bookshelves. Nonetheless, it is another in a series of natural histories
that are valuable in elucidating issues in socioecology such as those Stanford and
others are now addressing. Such studies always make lasting contributions to
Lynne A. Isbell
Department of Anthropology
University of California
Clutton-Brock,T.H. Female transfer and inbreeding avoidance in social mammals.
NATURE 337:70-72, 1989.
Crook, J.H.; Gartlan, J.S. Evolution of primate societies. NATURE 210:1200-1203,
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R. The relation between ecology and social
structure in primates. SCIENCE 176:863874, 1972.
Harcourt, A.H. Strategies of emigration and
transfer by primates with particular refer-
302 / Isbell
ence to gorillas. ZEITSCHRIFT FUR
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Hausfater, G. Intergroup behavior of freeranging rhesus monkeys (Mucucu mulutta).
Isbell, L.A. Contest and scramble competition among primates: variation in female
aggression and ranging behavior. BEHAVIORAL ECOLOGY 2~143-155,1991.
Johnson, M.L; Gaines, M.S. Evolution of dispersal: theoretical models and empirical
tests using birds and mammals. ANNUAL
Marsh, C.W. Female transference and mate
choice among Tana River red colobus. NATURE 281568-569,1979.
Pusey, A.E.; Packer, C. Dispersal and philopatry. Pp. 250-266 in PRIMATE SOCIETIES. B.B Smuts; D.L. Cheney; R.M. Seyfarth; R.W. Wrangham; T.T. Struhsaker,
eds. Chicago, University of Chicago Press,
Robinson, J.G.; Janson, C.H. Capuchins,
squirrel monkeys, and atelines: socioecological convergence with Old World primates. Pp. 69-82 in PRIMATE SOCIETIES. B.B. Smuts; D.L. Cheney; R.M.
Seyfarth; R.W. Wrangham; T.T. Struhsaker, eds. Chicago, University of Chicago
Press, 1987.
Struhsaker, T.T. THE RED COLOBUS
MONKEY. Chicago, University of Chicago
Press, 1975.
van Schaik, C.P. The ecology of social relationships amongst female primates. Pp.
Oxford, Blackwell Scientific Publications,
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tactics, karger, langue, bangladesh, madhupur, xvii, langurs, capper, fig, 1991, 179, base, behavior, tab, stanford, ecology, review, craig, reproduction, plates
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