close

Вход

Забыли?

вход по аккаунту

?

Census habitat preference and polyspecific associations of six monkeys in the Lomako Forest Zaire.

код для вставкиСкачать
American Journal of Primatology 34295-307 (1994)
RESEARCH ARTICLE
Census, Habitat Preference, and Polyspecific
Associations of Six Monkeys in the Lomako Forest, Zaire
SCOTT MCGRAW
Department of Anthropology, State University of New York at Stony Brook, Stony Brook
This paper reports preliminary data on a number of poorly known cercopithecids inhabiting the Lomako Forest, Zaire. Data include those on density, biomass, group size, the relationship between group type (mono vs.
polyspecific) and forest type (mixed primary, secondary, monodominant
primary, and swamp), and vertical stratification. Species examined are
Colobus angolensis, Cercocebus aterrimus, Cercopithecus wolfi, Cercopithecus ascanius, Cercopithecus neglectus, and Allenopithecus nigroviridis.
The density and biomass for the Lomako Forest anthropoids (excluding
Cercopithecus neglectus and A. nigroviridis) are 165 ind/km2 and 1,034
kg/km2, respectively. Cercopithecus wolfi and Colobus angolensis are
found in group sizes similar to those reported from other sites while Cercopithecus ascanius, Cercocebus aterrimus, and A. nigroviridis display
group sizes unique to the Lomako. While Colobus angolensis, Cercocebus
aterrimus, Cercopithecus ascanius and Cercopithecus wolfi were found, to
varying extents, in all four forest types, Cercopithecus neglectus and A.
nigroviridis inhabited only swamp forest. The different species sort out
along vertical continua both within and between the four forest types.
0 1994 Wiley-Liss, Inc.
Key words: Cercopithecus, Allempithecus, Colobus, Cercocebus, ecology
and polyspecific associations
INTRODUCTION
Zaire is the most primate-rich country in Africa, with at least 24 anthropoid
and 8 prosimian species in 14 genera [Oates, 19851. Despite this extraordinary
diversity, few studies on monkey communities have been carried out in Zaire as
most field work on the cercopithecids of equatorial Africa has been conducted in
sites east (e.g., Uganda, Tanzania, Kenya) or west (e.g., Gabon, Cameroon, Nigeria, Ivory Coast) of the Congo basin. Long-term research on African monkeys is
rare and even basic information such as relative abundance and patterns of habitat
use are lacking for many taxa. In this paper, preliminary ecological data on a
number of poorly known cercopithecids living in the Lomako Forest, Zaire are
placed in the context of data from other field sites (see Table I for summary of data
from previous studies). Gautier-Hion et al. [19811 have suggested that the formaReceived for publication May 28, 1993; revision accepted March 9, 1994.
Address reprint requests to Scott McGraw c/o Dr. Randall Susman, Department of Anatomical Sciences,
School of Medicine, State University of New York a t Stony Brook, Stony Brook, NY 11794-8081.
0 1994 Wiley-Liss, Inc.
296 I McGraw
TABLE I. Comparative Data on Lomako Forest Monkeys*
x Body weight
Species
(kd
Group
size
Colobus
angolensis
9.9
6.6
Population
density
(ind/km2)
7.7
Groves [19731
Moreno-Black & Maples [19771
4.3
4.9
5.5
Cercocebus
aterrimus
Cercopithecus
wolfi
Cercopithecus
ascanius
Cercopithecus
neglectus
8
17.5
69
Horn [1987]
3.8
ND
ND
Thomas 119911
3.6
22, 23, 24
72
Cords [1984]
17-23
30-35
117
140
5,6
28
5.5
*ND
=
4.5
Struhsaker & Leland [19791
Quiris [1976]
Brennan [19851
Gautier-Hion & Gautier [19781
3.2
Allenopithecus
nigroviridis
References
Thomas [1991]
> 40
ND
Gautier [19851
no data. Body weights are averages of adult males and females.
tion of mixed-species groups within different forest types may be a response to
(among other things) varying risks of predation within each habitat. Data on the
number of group types within each habitat are presented to address this issue. The
species discussed are: Colobus angolensis (Angolan Black and White colobus), Cercocebus aterrimus (Black mangabey), Cercopithecus ascanius whitesidei (Redtail
monkey), Cercopithecus wolfi wolfi (Wolf‘s guenon), Cercopithecus neglectus (DeBrazza’s monkey), and Allenopithecus nigroviridis (Allen’s Swamp monkey).
THE STUDY SITE
The Lomako Forest is located in the interior of the Congo Basin (Zaire) between the Yekokora and Lomako Rivers a t 0.50’N, 21.05’E (Fig. 1). In addition to
the monkeys examined in this study, the Lomako Forest is home to a population of
pygmy chimpanzees (Pan paniscus) that has been the subject of study by members
of the Lomako Forest Pygmy Chimpanzee Project, based a t the State University of
New York a t Stony Brook, since 1979 [see Susman, 19841.
At least four gross vegetation types are found in the Lomako. (1) The majority
of the primary study site consists of approximately 35 km2 of lowland terra firma
forest. (2) Pockets of secondary growth that include sites of former hunting villages, manioc fields, and tree fall gaps are scattered throughout the terra firma
forest. (3) Areas of monodominant slope forest, comprised almost exclusively of
Gilbertiodendron dewevrei trees, crosscut the site along streams that feed the Lomako River. (4) Finally, the primary study site is bordered by extensive areas of
permanently inundated swamp forest that encroach into the evergreen forest via
stream flood plains (dominated by Sclesopermium manii). These vegetation types
are indicated in Figure 2.
Census of Lomako Forest Monkeys I 297
Fig. 1. The location of Lomako Forest within the Congo Basin.
Within the terra firma forest the main canopy layer is continuous, reaching
heights of between 30 and 40 m and dominated by species of Polyalthia and Scorodophloeus (e.g., Polyalthia suaueolens, Scorodophloeus zenkeri, Dialium zenkeri,
Zruingia robur, Celtis mildbraedi, Crudia laurentii). Emergent trees (e.g., Oxystigma oxyphyllum and Antiaris toxicaria) are common and may reach heights of
up to 55 m. The under story is more discontinuous and consists of a network of
lianes which allows for movement between forest layers. The lowest herbaceous
layer, consisting largely of Haumania liebrechtsiana and Palisota spp., usually
reaches heights no greater than 4 m [Malenky & Stiles, 19911. Further details on
the study site may be found in Susman et al. [19801, White [19861, and Malenky
[19901.
METHODS
Results presented here are from a 2-month study conducted in 1991. Twentyfour surveys were conducted along established trails and fruit transects in the
primary study site. Although the use of existing pathways may bias density estimates, artificial transects were not cut within the Lomako Forest so as not to
disturb the existing habitat. Sections of the trail system which curved more than
30" were excluded to avoid inadvertently recording animals twice which may have
been flushed farther along the transect routes. Three trails were censused eight
times each. Transect lengths were 5.1, 5.5, and 3 km, respectively (see Fig. 2 for
location of transects). All surveys began at 6:OO A.M. and were concluded by approximately 12:OO noon. On census days, trails were walked slowly and all observations
were made from the transect path only. Every attempt was made not to violate the
298 I McGraw
Fig. 2. Transect routes and major forest types found within the Lomako Forest study site.
assumptions of line transect sampling discussed by Burnham et al. [1980]: i.e., (1)
that monkeys directly on the transect were never missed, (2) that monkeys were
fixed a t the initial sighting location and none were counted twice, (3) that distances were measured exactly (estimated to the nearest meter), and (4)that sightings were independent events. After Rodman [1978], the following data were collected a t all localities: (1)time of sighting, (2) location on transect, (3) forest type,
(4) distance to first animal detected, (5) species present, (6) group type (mono- or
poly-specific; various definitions of poly-specific associations have been employed
by other workers [e.g., Bernstein et al., 1976; Waser, 1986a; Cords, 1987; Mitani,
19911. In this study, I followed the rationale of Struhsaker [1981] who recorded
poly-specific associations “when two or more social groups were spatially intermingled; this usually means they are in the same or contiguous tree and within 20
m of one another” [Gartlan & Struhsaker, 1972; Struhsaker, 1975]), (7) number
of animals sighted, (8) height of first animal observed, (9) activity of first animal
sighted, and (10) foods consumed.
Using the recommendations of the National Research Council [ 19811, transect
Census of Lornako Forest Monkeys / 299
TABLE 11. Maximum Reliable Sighting Distances
Used for Density Calculations
Species
Cercopithecus ascanius
Cercopithecus wolfi
Cercocebus aterrimus
Colobus angolensis
Sighting distance (m)
N
30
36
40
45
a7
72
107
19
strip width was determined using the method of maximum reliable sighting distance. Since sighting distances used for the estimation of densities were found to
vary with species, densities were calculated using taxon specific distances. These
distances are presented in Table 11.
Noncensus days were spent following groups and recording observations ad
libitum. Upon contacting a group, I recorded (1)time of sighting, (2) forest type, (3)
species present, (4) initial group count, (5) height of first animal observed, and (6)
activity of first animal sighted; subsequently animals were followed for as long as
possible to determine the reliability of group counts obtained from census
transects. This was accomplished by comparing initial group counts with counts
made a t 5-minute intervals during follows. Data collected on these days were not
used for density/biomass estimates but rather to supplement data on forest preference, group size, vertical distribution, and poly-specific associations derived from
transect censusing. Additional time was allotted to specifically investigate the
flooded riverine forests which border the primary study site. Every fourth day, I
traveled through the swamp forest via a number of routes leading to the river
system, collecting data in the fashion described above. Systematic forays were
made on foot along the river's smaller tributaries and some portions of the inundated forest were investigated from a canoe. It must be emphasized that the four
categories of habitat are found in different proportions and that equal sampling
time was not spent within each vegetation type. Therefore, figures on habitat use
do not necessarily represent how much time each monkey spends in each forest
type. Nevertheless, these data can give a preliminary indication of gross habitat
use a s the census transects sampled a t least a portion of ail four forest types
(Fig. 2).
RESULTS
Density, Biomass, and Group Size Estimates
Results of density, biomass, and group size estimates are presented in Table
111. Data on mean group counts are derived both from census counts (when I was
reasonably certain the whole group had been counted) and from non-census follows
when the entire group could be counted repeatedly. Cercocebus aterrimus ( x group
size = 10.9) is the most abundant monkey in the study site (73.1 ind/km2)followed
by nearly equal numbers of Cercopithecus ascanius (42.8 ind/km2) and Cercopithecus wolfi (44 ind/km2)with mean group sizes of 14.7 and 10.1, respectively. Colobus angolensis (5.8 ind/km2) was encountered relatively infrequently and in
smaller groups ( x group size = 5) than the above taxa. Allenopithecus nigrouiridis
and Cercopithecus neglectus were never observed along transect routes and density
estimates were therefore not attempted for them. It is difficult to speculate on the
relative abundance of these swamp taxa without systematic investigations of
the inundated forest throughout the Lomako River Basin. However, considering
the limited time spent exploring their habitat and the regularity with which these
300 I McGraw
TABLE 111. Group Size, Density, and Biomass Estimates*
Taxon
Cercocebus
aterrimus
Colobus
angolensis
Cercopithecus
ascanius
Cercopithecus
wolfi
Cercopithecus
neglectus
Allenopithecus
nigrouiridis
Pan paniscus
X
X
Total
observations
Group
counts
Group
size"
Group
sizeb
Density
(indikm2)
Body
weight
146
77
10.9
10.2
73.1
8d
585
27
21
5
5
5.8
9.9"
57
105
24
14.7
12.7
42.8
3.6"
154
101
37
10.1
12
44.2
3.8"
168
12
5
3
ND
-
5.5
7
3
4
ND
-
4.5
NA
NA
NA
ND
2'
Total
165 indikm'
35
Biomass
70
1,034
*NA = not applicable; ND = no data.
Tombined census and noncensus data
bCensus data only.
'Badrian & Malenky [19841.
dTervuren Museum (n = 4).
'Thomas [19911.
monkeys were either observed or heard, it is probable that these two species are
fairly common throughout the Lomako River system.
Group Types and Forest Use
Within the study area, the Lomako primates were not distributed evenly
throughout the four categories of vegetation types and most of the Lomako monkeys displayed strong tendencies to associate with one or more different species.
Table IV summarizes the relative frequency with which different group types of
each species were found in different forest categories while Table V reports the
composition of each mixed-species association.
Cercocebus aterrimus, Cercopithecus wolfi, and Cercopithecus ascanius were
most often encountered in some combination of mixed-species association. Cercocebus aterrimus was found most often in primary forest, either alone (n = 44)or in
association with other taxa (n = 59). The black mangabey was encountered rarely
in secondary and swamp forest while it used slope forest in proportions equal to
those used by Cercopithecus ascanius and Cercopithecus wolfi. Cercopithecus ascanius and Cercopithecus wolfi were most often encountered in terra firma forest
although with different frequencies. Both guenons were found in slope and swamp
forest in nearly equal proportions. Mono-specific groups of Cercopithecus wolfi
were observed in secondary forest only once while mono-specific groups of Cercopithecus ascanius were recorded in this vegetation type on fifteen occasions. It is
interesting to note that groups comprised solely of Cercocebus aterrimus and Cercopithecus wolfi were nearly three times more common than the mixed groups of
Cercocebus aterrimus and Cercopithecus ascanius.
Colobus angolensis was observed a n equal number of times in primary and
slope forest. This is significant because slope forest makes up only a small percentage of the total study site. It is possible that the frequency with which Colobus
Census of Lomako Forest Monkeys / 301
TABLE IV. Number of Observations of Group Types in Different Forest Types
1"
Species
Cercocebus aterrimus
Cercopithecus wolfi
Cercopithecus ascanius
Colobus angolensis
Cercopithecus neglectus
Allenopithecus nigroviridis
Slope
2"
Swamp
Mono
Poly
Mono
Poly
Mono
Poly
Mono
Poly
44
12
19
4
-
59
56
36
4
-
0
1
15
1
-
6
7
11
1
-
12
2
7
4
-
15
17
13
4
-
-
__
7
3
1
5
12
5
3
3
3
1
0
2
TABLE V. Composition and Number of Poly-Specific Groups
Polyspecific groups of two species
Cercocebus aterrimus
Colobus angolensis
CercoDithecus ascanius
Colobus angolensis
Cercopithecus ascanius
Cercopithecus wolfi
0
-
13
1
34
1
12
N
Polyspecific groups of three species
C. aterrimus, C. wolfi, and C. ascanius
C. angolensis, C. wolfi, and C. ascanius
C. aterrimus, C. wolfi, and C. angolensis
Allenopithecus nigrouiridis, C. wolfi, and C. ascanius
Polyspecific groups of four species
C. aterrimus. C. ascanius. C. wolfi. and C. angolensis
26
1
2
2
5
angolensis was found in slope forest was a seasonal phenomenon as the study was
conducted during the period in which Gilbertiodendron dewevrei was flowering.
The preliminary data here indicate that these flowers are a preferred food of
Colobus angolensis in the Lomako which may explain the high occurrence of the
species in this habitat. With the exception of mono-specific groups in swamp forest,
there seemed to be little association between forest and group type for Colobus
angolensis.
Allenopithecus nigroviridis and Cercopithecus neglectus were never observed
outside of the swamp forest, although the remaining species were found in this
habitat at various times and in various associations. Cercopithecus neglectus was
never observed associating with other taxa while Allenopithecus nigroviridis was
found in mixed groups twice.
Vertical Stratification
Figure 3 presents a bar graph of the height of first animal sighted with data
from all four forest types pooled. Multiple comparisons among means revealed
significant differences for every combination of taxa at the .01 level. A stepped
series appears with Cercopithecus ascanius occupying the lowest tier followed respectively by Cercopithecus wolfi, Cercocebus aterrimus, and Colobus angolensis.
In nearly 50% of all observations, Cercopithecus ascanius was observed below 10 m
and was frequently seen on the ground or on low hanging lianes foraging for fallen
fruit and insects. Mean height for Cercopithecus wolfi was approximately 5 m
higher than that of Cercopithecus ascanius while Cercocebus aterrimus used the
302 I McGraw
Cercopithecus arcaniut
Cercopifhecus wolf1
Cercoeebur aterrirnut
Colobus angolensis
Percent observed
All pairwise comparisons significant at .01 level
Fig. 3. Height of first animal sighted obtained by pooling data from the four forest types.
middle and upper canopy layers extensively. Although it was never observed on
the ground in the course of this study, tracks of Cercocebus aterrimus were frequently found along stream beds throughout the study site and other workers in
the Lomako confirm that the black mangabey does occasionally descend to the
forest floor (Thompson-Handler, personal communication). Colobus angolensis was
found at the greatest height of all species. The Angolan colobus was frequently
seen feeding or sunning itself at the tops of emergent Gilbertiodendron dewevrei
trees during the hottest parts of the day. In addition, footprints of Colobus angolensis were found along stream beds in the Lomako Forest where local guides insist
the monkey digs for water worms. Both Allenopithecus nigroviridis and Cercopithecus neglectus were observed most often on the ground. Allenopithecus nigroviridis was not seen foraging above 2 m although Cercopithecus neglectus was
observed feeding a t levels between 10 and 15 m above the ground.
To determine whether stratification was consistent across forest types, mean
height was calculated separately for each forest type (Fig. 4).(It is important to
note that these heights are not scaled to those available within each forest type.
This is most significant for heights recorded in secondary forest: figures reported
are lower for all species in secondary forest because this habitat in the Lomako is,
by definition, between 15 and 30 m shorter that the other three forest types.) In
general, Colobus angolensis was consistently observed a t the upper levels of all
forest types while Cercocebus aterrimus was found slightly lower. The two guenons
were most often found in the mid-canopy of primary and slope forest while in
swamp forest, Cercopithecus ascanius and Cercopithecus wolfi tended to frequent
lower levels.
DISCUSSION
Information on densities and biomasses of whole African primate communities
is scarce. The preliminary data presented here indicate that the density and biomass of the Lomako Forest primates are comparable to those a t other African sites.
Estimates of the partial Lomako primate density (165 ind/km2) and biomass (1,034
kglkm') (excluding the swamp taxa Allenopithecus nigroviridis and Cercopithecus
Census of Lomako Forest Monkeys I 303
35
30
v)
& 25
+
0
n
.....
E 20
n
...........
c
.-
2
15
Dl
I".- l o
L
5
0
Primary
Mbau
Swamp
Secondary
Forest Ty pe
0C. angolensis
C. aterrimus
C. ascanius
0C. wolfi
Fig. 4. Height of first animal sighted within each forest type.
neglectus) are intermediate between those reported from the Ituri (112 indlkm' and
710 kg/km2) [Thomas, 19911 and Kibale forests (549 ind/km2 and 2217 kg/km')
[Struhsaker, 1975; Oates, 19771. While estimated primate densities for the Lomako fall within the range of West African sites (132-326 ind/km2),the Lomako's
primate biomass is greater than that reported from any West African locality
(524-761 kg/km') [Bourliere, 1985; Thomas, 19911. The Lomako estimates do not
include data on the swamp taxa and it is difficult to predict how much the addition
of these species would affect the total figures, since densities and group sizes for
Cercopithecus neglectus and Allenopithecus nigrouiridis are believed to vary widely
[see Gautier, 1985; Gautier-Hion & Gautier, 1978; Quiris, 1976; Brennan, 19851.
Furthermore, because the assumptions and biases of different census methods can
result in widely varying density and biomass estimates, comparisons are necessarily tentative.
In general, most of the Lomako monkeys were found at individual densities
and in group sizes similar to those reported from most other sites with similar taxa
(see Table I). Notable exceptions include the much larger groups of Allenopithecus
nigrouiridis observed by Gautier [ 19853 near Mbandaka, Zaire, the larger groups
of Cercocebus aterrimus observed near Lake Tumba, Zaire [Horn, 19873, and the
larger groups and higher densities of Cercopithecus ascanius reported from Kibale
[Struhsaker & Leland, 19791.
Despite its comparatively high density and biomass levels, the Lomako contains among the lowest number of species of any site within the Congo Basin.
304 I McGraw
Seven anthropoids inhabit the Lomako while 13 are found in the Ituri Forest
[Thomas, 19911, 9 at Wamba [Kano & Mulavwa, 19841, and 8 at Lake Tumba
[Horn, 19871. Conspicuously absent are (1)multiple folivores (e.g., three colobines
inhabit the Ituri Forest and two are found at both Wamba and Lake Tumba) and
(2) multiple ground-dwelling species (e.g., five largely terrestrial species are found
in Ituri Forest). These deficiencies are intriguing considering the mosaic of habitats available at the Lomako and the high productivity of the forest [Malenky,
19901. Although hunting is forbidden in the immediate study site, the monkey
populations are considered threatened and it is possible that certain taxa have
already been hunted to extinction [Badrian & Badrian, 19771. For example,
Talapoin monkeys were never sighted in the Lomako, despite their otherwise
widespread distribution south of the Zaire River [e.g., see Lernould, 19881. On the
other hand, the impoverished fauna and low level of endemism might better be
explained on biogeographic grounds: despite its location within the south-central
forest block, the Lomako does not appear to be a n interfluvial refugium [Colyn et
al., 19911. In either case, further investigation of the surrounding areas is needed
to confirm the taxonomic inventory of the Lomako River Basin.
To varying degrees, the monkeys show differential forest use. The most dramatic instance involves Cercopithecus neglectus and Allenopithecus nigroviridis
which, despite the proximity of other forest types, were never found outside of the
inundated swamp forest. Beyond the swamp forest, tendencies to use single habitats appear less marked and these data indicate that most species are capable of
exploiting all vegetation types available in the Lomako.
The Lomako Forest monkeys have been shown to range throughout a variety
of habitats a t other locations. However, because most have not been studied in
detail, the extent to which each species displays preferential habitat use is unknown. For example, in the Ituri, Thomas [1991] noted that Colobus angolensis
spent considerable time in riparian forest and was not found disproportionately in
mono-dominant, Gilbertiodendron dewevrei (slope) forest. Furthermore, Colobus
guereza, a close relative of the Angolan black and white colobus monkey, has been
touted as a frequent user of secondary forest [Oates, 19771. Interestingly, the
Lomako black and white colobus was observed in secondary forest on only two
occasions. Additional time should be budgeted to investigate those factors responsible for differential habitat utilization in this and the other monkeys.
Colobus angolensis, Cercocebus aterrimus, Cercopithecus ascanius, and Cercopithecus wolfi appear to occupy distinct forest levels both within and across the
different forest types. In general, this paper’s findings on Colobus angolensis, Cercocebus aterrimus, and Cercopithecus ascanius concur with comparable data from
other studies [Thomas, 1991; Horn, 1987; Groves, 1973; Struhsaker, 19691. While
little to no information exists for Cercopithecus wolfi itself, other members of the
Mona super-species (Cercopithecus mona, Cercopithecus campbelli, Cercopithecus
pogonias) are known to prefer the mid and lower canopy layers [Struhsaker, 19691
which agrees with the observations contained herein. The preliminary observations on Allenopithecus nigroviridis and Cercopithecus neglectus support previous
reports that these swamp taxa are semi-terrestrial [Gautier, 1985; Gautier-Hion &
Gautier, 1978; Kingdon, 19881.
Mixed-species groups have been reported in five of six Lomako monkeys studied at other sites [Groves, 1973; Moreno-Black & Maples, 1977; Horn, 1987; Gautier, 1985; Thomas, 1991; Cords, 1987; Gautier-Hion, 1988al. Functional explanations for poly-specific associations have most often focussed on the benefits either
of increased foraging efficiency [e.g., Gautier-Hion, 1988bl or the reduction of
predator pressure [e.g., Cords, 19841. While data are not yet sufficient to quantify
Census of Lomako Forest Monkeys / 305
the degree of feeding competition among the Lomako monkeys, preliminary information from this and other studies suggests that there may be a high amount of
dietary overlap between species [Cords, 1987; Horn, 19871. In addition, evidence is
available that the Lomako monkeys are subject to significant predation pressure.
The crowned hawk eagle (Stephanoaetus coronatus), a known monkey predator
[Gartlan & Struhsaker, 1972; Brown, 1982; Skorupa, 19891 is common throughout
the Lomako where it is known to claim monkeys of all sizes [Badrian & Malenky,
19841. Furthermore, monkeys are believed to actively avoid associating with
pygmy chimpanzees [Malenky, 19901which have been implicated as monkey hunters a t other sites [Horn, 19801. It has been suggested [Gautier-Hion et al., 19811
that structural differences in vegetation types (e.g., low, dense secondary forest vs.
high, open primary forest) may imply variable risks of predation from aerial (e.g.,
eagles) and scansorial (e.g., felids, snakes, and pygmy chimpanzees) hunters. If
poly-specific groups have evolved as a response to these threats, then one might
expect differential formation of poly-specific groups within each forest type. For
example, that Cercopithecus wolfi was found more often in poly-specific groups in
primary forest may be made possible by the mutual benefit of increased sentinels.
Although such hypotheses remain speculative, one goal of future studies should be
to assess the relative risks of predation within different forest types while looking
for patterns in group formation among monkeys with similar amounts of dietary
overlap.
The mosaic of habitats found within the Lomako forest provides a good opportunity for workers interested in differential habitat use to conduct natural experiments in comparative primate biology. The data presented here (which should be
viewed as preliminary) are intended to provide the basis for future studies in which
particular attention should be directed toward: (a) confirming the taxonomic inventory of the broader area, (b) assessing the degree of dietary overlap among the
local cercopithecids, (c) evaluating the relative risk of predation within each forest
type, and (d) determining the association between group type and forest utilization.
CONCLUSIONS
1. The density of the Lomako Forest anthropoids (excluding Cercopithecus
neglectus and Allenopithecus nigroviridis) is estimated at 165 ind/km2 which corresponds to an overall biomass of 1,034 kg/km2.While anthropoid species richness
is low (seven species), anthropoid biomass and density compare favorably with
estimates from other African forests.
2. Most of the Lomako primates, for which comparable data exist, are found a t
densities and in group sizes similar to those reported from other sites. Notable
exceptions include smaller groups of Cercopithecus ascanius, Cercocebus aterrimus,
and Allenopithecus nigroviridis in the Lomako.
3. The monkeys are not distributed randomly throughout the different forest
types. While Colobus angolensis, Cercocebus aterrimus, Cercopithecus ascanius,
and Cercopithecus wolfi were found, to varying extents, in all four forest types,
Cercopithecus neglectus and Allenopithecus nigroviridis were never observed outside of the swamp forest.
4.The monkeys sort out vertically from one another both within and between
the four forest types. In general, Colobus angolensis occupied the highest canopy
layer followed by Cercocebus aterrimus, Cercopithecus wolfi, and Cercopithecus
ascanius.
5 . Poly-specific associations are common in the Lomako Forest. Further atten-
306 I McGraw
tion should be directed toward determining whether the formation of poly-specific
groups is associated with different forest types.
ACKNOWLEDGMENTS
I thank Dr. Zana Ndontoni (Directeur General du CRSN), and the Centre de
Recherche en Sciences Naturelle (CRSN) for permission to study in the Lomako
Forest. I a m indebted to my advisor, Randall Susman, for the opportunity to work
in the Lomako Forest. Helpful comments and discussions were provided by Randall
Susman, John Fleagle, Charlie Janson, Richard Malenky, Nancy Thompson-Handler, Francis White, Tony Falsetti, Chris Wall, Dan Schmitt, and four anonymous
reviewers. Thanks to Lucille Betti-Nash who prepared the maps. Funding for the
project was furnished by NSF Grant BNS-870687 to R.L. Susman, Conservation
International and the Chicago Zoological Society.
REFERENCES
Badrian, A.; Badrian, N. Pygmy chimpanzees. ORYX 13:463-472, 1977.
Badrian, N.; Malenky, R. Feeding ecology of
Pan paniscus in the Lomako Forest, Zaire.
Pp. 275-299 in THE PYGMY CHIMPANZEE. R.L. Susman, ed. New York, Plenum
Press, 1984.
Bernstein, 1,s.; Balcaem P.; Dresdale,
Gouzoules, H.; Kavanagh, M.; Patterson,
T.; Neyman-Warner, P. Differential effects
of forest degradation on primate populations. PRIMATES 17:401-411, 1976.
Bourliere, F. Primate communities: Their
structure and role in tropical ecosystems.
INTERNATIONAL JOURNAL OF PRIMATOLOGY 6:l-26, 1985.
Brennan, J. DeBrazza's monkeys (Cercopithecus neglectus) in Kenya: Census, distribution, and conservation. AMERICAN
JOURNAL OF PRIMATOLOGY 8:269277, 1985.
Brown, L.H. The prey of the Crowned Eagle
Stephanoaetus coronatus in Central
Kenya. SCOPUS 6:91-94, 1982.
Burnham, K.P.; Anderson, D.R.; Laake, J.L.
Estimation of density from line transect
sampling of biological populations. WILDLIFE MONOGRAPHS 72,1980.
Colyn, M. Distribution of guenons in the
Zaire-Laulaba-Lomani river system. Pp.
104-124 in A PRIMATE RADIATION:
EVOLUTIONARY BIOLOGY OF THE
AFRICAN GUENONS. A. Gautier-Hion;
F. Bourliere; J. Gautier; J. Kingdon, eds.
Cambridge, Cambridge University Press,
1988.
Cords, M. MIXED-SPECIES GROUPS OF
CERCOPZTHECUS MONKEYS IN THE
KAKAMEGA FOREST, KENYA. Ph.D.
Thesis. Berkeley, CA, University of California, 1984.
Cords, M. Mixed-species associations of Cercopithecus monkeys in the Kakamega Forest, Kenya. UNIVERSITY OF CALIFOR-
NIA PUBLICATIONS IN ZOOLOGY NO.
117. Berkeley, University of California
Press, 1987.
Gartlan, J.S.; Struhsaker, T.T. Polyspecific
associations and niche separation of rainforest anthropoids in Cameroon, West Africa. JOURNAL OF ZOOLOGY 168:221266, 1972.
Gautier, J.P. Quelques caracteristiques
ecologiques du singe des marais Allenopithecus nigroviridis Lang 1923. TERRE ET
VIE 40:331-342, 1985.
Gautier-Hion, A. Polyspecific associations
among forest guenons: Ecological, behavioral and evolutionary aspects. Pp.
452-476. in A PRIMATE RADIATION
EVOLUTIONARY BIOLOGY OF THE
AFRICAN GUENONS. A. Gautier-Hion;
F. Bourliere; J . Gautier; J . Kingdon, eds.
Cambridge, Cambridge University Press,
1988a.
Gautier-Hion, A. The diet and dietary habits
of forest guenons. Pp. 257-283 in A PRIMATE RADIATION: EVOLUTIONARY
BIOLOGY OF THE AFRICAN GUENONS. A. Gautier-Hion; F. Bourliere; J.
Gautier; J. Kingdon, eds. Cambridge, Cambridge University Press, 1988b.
Gautier-Hion, A.; Gautier, J. Le singe de
Brazza:
Une
strategie
originale.
ZEITSCHRIFT FUR TIERPSYCHOL 46:
84-104, 1978.
Gautier-Hion, A.; Gautier, J.;Quiris, R. Forest structure and fruit availability as complementary factors influencing the habitat
use by a troop of monkeys (Cercopithecus
cephus). REVUE d'ECOLOGIE (TERRE
VIE) 351511-536, 1981.
Groves, C. Notes on the ecology of the Angola colobus (Colobus angolensis P.L.
Sclater 1860) in N.E. Tanzania. FOLIA
PRIMATOLOGICA 20:12-26, 1973.
Horn, A. Some preliminary observations on
the ecology of the bonobo chimpanzee (Pan
Census of Lomako Forest Monkeys / 307
paniscus Schwarz 1929) near Lake Tumba,
Zaire. FOLIA PRIMATOLOGICA 34:145169,1980.
Horn, A. The socioecology of the black mangabey (Cercocebus aterrimus) near Lake
Tumba, Zaire. AMERICAN JOURNAL OF
PRIMATOLOGY 12:165-180, 1987.
Kano, T.; Mulavwa, M. Feeding ecology of
the pygmy chimpanzees (Pan paniscus) of
Wamba. Pp. 233-274 in THE PYGMY
CHIMPANZEE. R.L. Susman, ed. New
York, Plenum Press, 1984.
Kingdon, J. Comparative morphology of
hands and feet in the genus Cercopithecus.
Pp. 184-193 in A PRIMATE RADIATION:
EVOLUTIONARY BIOLOGY OF THE
AFRICAN GUENONS. A. Gautier-Hion;
F. Bourliere; J. Gautier; J. Kingdon, eds.
Cambridge, Cambridge University Press,
1988.
Lernould, J.-M. Classification and distribution of guenons: A review. Pp. 54-78 in
A PRIMATE RADIATION: EVOLUTIONARY BIOLOGY OF THE AFRICAN
GUENONS. A. Gautier-Hion; F. Bourliere; J. Gautier; J . Kingdon, eds. Cambridge, Cambridge University Press,
1988.
Malenky, R.K. ECOLOGICAL FACTORS
AFFECTING FOOD CHOICE AND SOCIAL ORGANIZATION IN PAN PANZSCUS. Ph.D. Thesis. State University of
New York a t Stony Brook, 1990.
Malenky, R.K.; Stiles, E. Distribution of terrestrial vegetation and its consumption by
Pan paniscus in the Lomako Forest, Zaire.
AMERICAN JOURNAL OF PRIMATOLOGY 23:153-169, 1991.
Mitani, M. Niche overlap and polyspecific
associations among sympatric cercopithecids in the Campo Animal Reserve, Southwestern Cameroon. PRIMATES 32:137151,1991.
Moreno-Black, G.; Maples, W.R. Differential
habitat utilization of four Cercopithecidae
in a Kenyan forest. FOLIA PRIMATOLOGICA 27:85-107,1977.
National Research Council. TECHNIQUES
FOR THE STUDY OF PRIMATE POPULATION ECOLOGY. Washington, National Academy Press, 1981. Oates, J.F.
ACTION PLAN FOR AFRICAN PRIMATE CONSERVATION: 1986-1990.
New York; IUCN/SSC Primate Specialist
Group, 1986.
Oates, J.F. The guereza and its food. Pp.
275-321 in PRIMATE ECOLOGY: STUDIES OF FEEDING AND RANGING BEHAVIOR IN LEMURS, MONKEYS AND
APES C.H. Clutton-Brock, ed. New York:
Academic Press, 1977.
Oates, J.F. ACTION PLAN FOR AFRICAN
PRIMATE CONSERVATION: 1986-1990.
IUCNISSC PRIMATE SPECIALISTS
GROUP, 1985.
Quiris, R. Donnees comparatives sur la socioecologie de huit especes de Cercopithecidae vivant dans une meme zone de foret
primitive periodiquement inondee (nordest du Gabon). TERRE ET VIE 30:193209,1976.
Rodman, P. Diets, densities, and distributions of Bornean'primates. Pp. 465-478 in
THE ECOLOGY OF ARBOREAL FOLIVORES. G. Montgomery, ed. Washington,
D.C., Smithsonian Institution Press, 1978.
Skorupa, J. Crowned Eagles Strephanoaetus
coronatus in rainforest: Observations on
breeding chronology and diet a t a nest in
Uganda. IBIS 131(2):294-298, 1989.
Struhsaker, T.T. Correlates of ecology and
social organization among African cercopithecines. FOLIA PRIMATOLOGICA 11:
80-118, 1969.
Struhsaker, T.T. THE RED COLOBUS
MONKEY. Chicago, The University of
Chicago Press, 1975.
Struhsaker, T.T. Polyspecific associations
among tropical rain forest primates.
ZEITSCHRIFT FUR TIERPSYCHOLOGIE 57:268-304,1981.
Struhsaker, T.T.; Leland, L. Socioecology of
five sympatric monkey species in the
Kibale Forest, Uganda. Pp. 159-228 in
ADVANCES IN THE STUDY OF BEHAVIOR, VOLUME 9. J.S. Rosenblatt; R.A.
Hinde; C. Beer; M.C. Busnel, eds. New
York, Academic Press, 1979.
Susman, R.L. ed. THE PYGMY CHIMPANZEE. New York, Plenum Press, 1984.
Susman, R.L.; Badrian, N.L.; Badrian, A.J.
Locomotor behavior of Pan paniscus in
Zaire. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 53:69-80, 1980.
Thomas, S. Population densities and patterns of habitat use among anthropoid primates of the Ituri Forest, Zaire. BIOTROPICA 23(1):68-83, 1991.
Waser, P. Interactions among primate species. Pp. 210-226 in PRIMATE SOCIETIES. B. Smuts; D. Cheney; R. Seyfarth; R.
Wrangham; and T. Strushaker, eds. Chicago, The University of Chicago Press,
1986.
White, F.J. BEHAVIORAL ECOLOGY OF
THE PYGMY CHIMPANZEE. Ph.D. Thesis. State University of New York a t Stony
Brook, 1986.
Документ
Категория
Без категории
Просмотров
0
Размер файла
895 Кб
Теги
preference, habitat, polyspecific, associations, monkey, zaire, lomako, six, census, forest
1/--страниц
Пожаловаться на содержимое документа