Merker & Yustian 2007 Primates Habitat use analysis of Dian’s tarsier (Tarsius dianae) in a mixed species plantation in Sulawesi, Indonesia
Primates
DOI 10.1007/s10329-007-0072-z
SHORT COMMUNICATION
Habitat use analysis of Dian’s tarsier (Tarsius dianae)
in a mixed-species plantation in Sulawesi, Indonesia
Stefan Merker Æ Indra Yustian
Received: 16 August 2007 / Accepted: 18 September 2007
Ó Japan Monkey Centre and Springer 2007
Abstract To investigate the importance of mixed-species
plantations as a potential habitat for small arboreal
primates, we radio-tracked six Dian’s tarsiers (Tarsius
dianae) in such an area in Central Sulawesi, Indonesia, and
explored their selectivity for certain vegetation types. The
animals strongly favored sporadic dense shrubbery over
more open structures, yet they also utilized cash-crop
cultivations for hunting insects. This paper documents the
first habitat use analysis of tarsiers on agricultural land and
exemplifies the vital role of mixed-species plantations in
conserving wildlife when nearby forest is logged.
S. Merker (&)
Institute of Anthropology, Johannes-Gutenberg University
Mainz, Colonel-Kleinmann-Weg 2 (SB II),
55099 Mainz, Germany
e-mail: [email protected]
genetic characters mostly suggest that they would better be
grouped with monkeys and apes into the suborder Haplorhini (Martin 1990; Schmitz et al. 2001). With head-andbody lengths of about 12 cm, tarsiers weigh little more
than 100 g. These strictly faunivorous primates are endemic to the Greater Sunda Islands (all but Java) and the
Philippines.
Six tarsier species have been described thus far on the
Indonesian island of Sulawesi. Dian’s tarsier (Tarsius
dianae1) occurs in the lowlands and lower montane forests
of Central Sulawesi. This species lives in small groups of up
to seven individuals (Merker 2003). Population densities of
Dian’s tarsier have declined over the past years due to
intensified logging (Merker 2003; Merker et al. 2004). This
finding corroborates previous observations of imminent
threats to other tarsier species (MacKinnon and MacKinnon
1980; Leksono et al. 1997; Gursky 1998). Since the conversion of natural lowland forest into cash-crop plantations
appears to be an almost unstoppable process, assessing the
adaptability of tarsiers to such areas is essential for predicting these animals’ chances of survival.
Thoughts on the interface between tarsier biology and
agriculture are not new. Leksono et al. (1997) found tarsiers
in several cultivated areas of Sulawesi, reported on common
human misperceptions of these animals, e.g., that tarsiers
feed on cash-crops, and even suggested that tarsier populations could be managed as a natural pesticide. They did
not find these primates in areas of intensive coconut farming
but did observe them foraging in a mix of coconut and
cocoa cultivation. There, the animals frequently had sores
on their hands and anogenital regions. Some agricultural
practices inside the natural forest, however, might have
I. Yustian
Department of Biology, Sriwijaya University,
Palembang, Indonesia
1
Shekelle et al. (1997) pointed out this might be a junior synonym to
T. dentatus.
Keywords Cocoa Home range Primates
Radio tracking Tarsius dentatus
Introduction
Deforestation and habitat modification cause the decline of
primate populations around the tropical world (Johns and
Skorupa 1987). In Indonesia, this is not only true for the
large and space-demanding species such as orang-utans,
gibbons or macaques, but also for the lesser-known, smallbodied, and nocturnal tarsiers. These animals were
formerly classified along with lemurs and lorises as prosimians (Simpson 1945), yet anatomical, reproductive, and
123
Primates
desirable effects on tarsiers. Small forest coffee gardens, for
instance, positively affect Dian’s tarsier population densities and ranging patterns (Merker et al. 2004, 2005; Merker
2006).
A common and increasingly important practice in
Indonesia—mostly due to scattered land ownership and
crop rotation—is to cultivate several crop species side by
side. In Madagascar, lemur densities in such mixed-species
plantations are high (Ganzhorn 1987). The study reported
here aimed at revealing the habitat use of Dian’s tarsiers in
such an area in Central Sulawesi, Indonesia. Of particular
importance was the identification of typical vegetation
structures crucial for the presence of tarsiers in this
disturbed habitat.
Methods
From August to October 2001, five tarsier groups were
located in a 25-ha mixed-species plantation close to the
northeastern boundary of Lore-Lindu National Park,
Sulawesi, Indonesia (01°110 50@S, 120°090 26@E, 650–730 m
asl). This plantation comprised cocoa, maize, bamboo, and
the leguminous tree Gliricidia sepium (Jacq.) Steud. mostly
being used as living fence posts, fodder or fuelwood, and
for crop shade and improved fallow. The rhizomatous
perennial grass Imperata cylindrica L. (alang–alang), a
colonizer of degraded humid tropical forest soils, dominated the fallow land between cultivated crops. A patch of
young secondary forest with a canopy height of ca. 10 m
constituted the edge of the plantation towards old-growth
natural forest. Six different vegetation types were mapped
(Fig. 1) using measuring tape and a compass.
Nine tarsiers were captured using mist nets opened at
dusk and dawn in the vicinity of their sleeping sites. Six
adult females (from five groups, Fig. 1) were fitted with
3.3-g radio collars (Holohil Systems, Carp, ON, Canada)
and were subsequently radio-tracked over the course of
2 weeks. The choice of females as focal animals was due to
the design of a more comprehensive research project
comparing tarsier ranging patterns between different habitats (Merker et al. 2004, 2005; Merker 2006).
Data collection comprised shifts in the evening (1800–
2200), in the morning (0400–0630), and full-night follows. Home ranges were estimated by drawing minimum
convex polygons (MCPs) around the outermost data
points (Fig. 1). Since bearings within full-night shifts
were taken every 15 min (every 40 min during the other
shifts), they were likely to be intercorrelated (Merker
2003) and therefore omitted from the analysis described
here. Thus, a total of 32 track points (n = 31 for F5) were
available for each animal to be used in a habitat use
analysis.
123
Fig. 1 Study plot with six different vegetation types, home ranges of
six female Dian’s tarsiers (F1–F6) and commonly used tarsier
sleeping sites
The MCPs were superimposed on the map of vegetation
types (Fig. 1). The percentage of a particular vegetation
type within a tarsier home range was considered as available area. To determine the utilized fragments, data points
were plotted on the habitat map. The proportional use of
vegetation types was calculated by dividing the number of
locations in each fragment by the total number of track
points for this animal. The proportions of available vs.
utilized types were compared using a Wilcoxon signedrank test (Wilcoxon 1945). To test for selection or avoidance of particular structures, Ivlev’s electivity index Ei was
calculated for each vegetation type as Ei = (ui - ai)/
(ui + ai) where ui is the mean proportion of observations in
vegetation type i (habitat utilized) and ai is the mean proportion of vegetation type i available in the tarsier home
ranges (Lechowicz 1982).
Results
Tarsiers avoided fallow land and maize fields and strongly
selected dense shrubbery for sleeping and traveling
(Table 1). Young secondary forest, Imperata cylindrica
grassland, bamboo groves, and cocoa plantations were
Primates
Table 1 Abundance of vegetation types (as a percentage of tarsier home range) and their utilization by six female Dian’s tarsiers (in parentheses, in percent) in a mixed-species plantation in Sulawesi
Vegetation type
F1
Fallow/maize
12.6 (9.4)
Imperata
29.1 (28.1)
Cocoa
26.9 (9.4)
83.1 (71.9)
19.6 (18.7)
91.2 (84.4)
Shrubs
13.5 (18.8)
8.9 (25.0)
24.0 (46.9)
8.4 (15.6)
Bamboo
16.1 (34.4)
16.2 (12.9)
1.9 (0.0)
53.9 (54.8)
Secondary forest
F2
8.0 (3.1)
F3
49.0 (18.8)
F4
F5
0.4 (0.0)
7.3 (15.6)
30.0 (32.2)
F6
Mean
Ei
P
51.4 (25.0)
20.2 (9.4)
-0.37
0.04
4.9 (12.5)
6.9 (9.4)
0.15
0.29
28.8 (31.3)
46.6 (41.3)
-0.06
0.25
15.1 (31.3)
11.7 (22.9)
0.33
0.04
5.4 (7.9)
0.19
0.66
9.3 (9.1)
-0.01
0.66
Ei Ivlev’s electivity index, P for Wilcoxon signed-rank test, F female
Blanks denote the absence of a vegetation type in a particular home range. Mean calculated over all six home ranges, regardless of occurrence of
the vegetation type
neither avoided nor strongly selected. Consistently, tarsiers
utilized multiple kinds of vegetation including cocoa cultivations and Imperata cylindrica expanses. Only one
condition applied to all these observations—dense shrubs,
forest remnants or at least bamboo stands had to be nearby
to provide a suitable sleeping site. According to the land
owners, no insecticides were used but herbicides were
applied in this plot (2, 4-dimethylamine, glyfosate-isopropylamine). However, no unusual incidence of sores on the
hands or the anogenital region of these tarsiers was
detected. Although the tracking period was limited to
2 weeks, the tarsiers were observed over the course of ca.
10 weeks. During this time, the sleeping sites as shown in
Fig. 1 were consistently used, and tarsier ranges did not
change to a degree obvious to the human observer.
As the investigated plot lies in close vicinity to natural
forest (a potential source habitat), it cannot be assessed
here whether tarsier populations farther away from larger
forest patches are able to maintain sufficiently large
populations and gene exchange to avoid inbreeding. In
this particular plot, microsatellite analyses revealed no
reduced allelic variability and no increased relatedness
among these nine tarsiers indicating effective dispersal
(S.M., unpublished data). Follow-up studies including
further genetic analyses as well as a thorough investigation of reproductive success in disturbed areas are needed.
Based on the results of this short study, keeping or creating a mosaic of natural structures (e.g., shrubs, bamboo)
among the cash-crop cultivations as well as a shrub fringe
at the plantation border is recommended. Hedges or tracts
of Imperata cylindrica could effectively link tarsierfriendly plantations.
Discussion
Remnant forest patches or dense shrubbery can render
agricultural land as suitable tarsier habitat. As documented
in a previous study on tarsiers in this mixed-species plantation (Merker et al. 2005), tarsier group sizes are slightly
smaller, and the population density is significantly smaller
than in undisturbed forest. Furthermore, Merker et al.
(2005) found female home ranges to be significantly larger
than in pristine or less-disturbed plots. The authors mainly
attribute this to a reduced insect abundance in the plantations. Body weights, head-and-body lengths, ectoparasite
loads, and group composition were not found to be different between these study sites (Merker et al. 2005).
Although these population parameters indicate more difficult survival under such intensive anthropogenic influence
than in natural forest, such areas could be effective elements of metapopulations and stepping stones or corridors
for gene exchange. When forest is clear-cut, nearby plantations might serve as temporary refuge for a future
re-colonization of the succession areas.
Acknowledgments We wish to thank LIPI, PHKA, POLRI, and
BTNLL for granting research permits; Jatna Supriatna and Noviar
Andayani from UI Jakarta for officially sponsoring the studies; and
Leo, Sapri, and Thony for their help in the field. No animal was
harmed, and all radio-collars were retrieved after tracking. The study
was part of a larger research project supported by the German
Academic Exchange Service and the German National Academic
Foundation.
References
Ganzhorn JU (1987) A possible role of plantations for primate
conservation in Madagascar. Am J Primatol 12:205–215
Gursky S (1998) The conservation status of two Sulawesian tarsier
species: Tarsius spectrum and Tarsius dianae. Prim Conserv
18:88–91
Johns AD, Skorupa JP (1987) Responses of rain-forest primates to
habitat disturbance: a review. Int J Primatol 8:157–191
Lechowicz MJ (1982) The sampling characteristics of electivity
indices. Oecologia 52:22–30
Leksono SM, Masala Y, Shekelle M (1997) Tarsiers and agriculture:
thoughts on an integrated management plan. Sulawesi Primate
Newsl 4:11–13
123
Primates
MacKinnon J, MacKinnon K (1980) The behavior of wild spectral
tarsiers. Int J Primatol 1:361–379
Martin RD (1990) Primate origins and evolution—a phylogenetic
reconstruction. Chapman & Hall, London
Merker S (2003) Vom Aussterben bedroht oder anpassungsfähig? Der
Koboldmaki Tarsius dianae in den Regenwäldern Sulawesis.
PhD Thesis, Georg-August University, Göttingen. http://webdoc.
sub.gwdg.de/diss/2003/merker
Merker S (2006) Habitat-specific ranging patterns of Dian’s tarsiers
(Tarsius dianae) as revealed by radiotracking. Am J Primat
68:111–125
Merker S, Yustian I, Mühlenberg M (2004) Losing ground but still
doing well—Tarsius dianae in human-altered rainforests of
Central Sulawesi, Indonesia. In: Gerold G, Fremerey M,
Guhardja E (eds) Land use, nature conservation and the stability
123
of rainforest margins in Southeast Asia. Springer, Heidelberg, pp
299–311
Merker S, Yustian I, Mühlenberg M (2005) Responding to forest
degradation: altered habitat use by Dian’s tarsier Tarsius dianae
in Sulawesi, Indonesia. Oryx 39:189–195
Schmitz J, Ohme M, Zischler H (2001) SINE insertions in cladistic
analyses and the phylogenetic affiliations of Tarsius bancanus to
other primates. Genetics 157:777–784
Shekelle M, Leksono SM, Ichwan LLS, Masala Y (1997) The natural
history of the tarsiers of North and Central Sulawesi. Sulawesi
Primate Newsl 4:4–11
Simpson GG (1945) The principles of classification and a classification of mammals. Bull Am Mus Nat Hist 85:1–350
Wilcoxon F (1945) Individual comparisons by ranking methods.
Biometrics 1:80–83
DOI 10.1007/s10329-007-0072-z
SHORT COMMUNICATION
Habitat use analysis of Dian’s tarsier (Tarsius dianae)
in a mixed-species plantation in Sulawesi, Indonesia
Stefan Merker Æ Indra Yustian
Received: 16 August 2007 / Accepted: 18 September 2007
Ó Japan Monkey Centre and Springer 2007
Abstract To investigate the importance of mixed-species
plantations as a potential habitat for small arboreal
primates, we radio-tracked six Dian’s tarsiers (Tarsius
dianae) in such an area in Central Sulawesi, Indonesia, and
explored their selectivity for certain vegetation types. The
animals strongly favored sporadic dense shrubbery over
more open structures, yet they also utilized cash-crop
cultivations for hunting insects. This paper documents the
first habitat use analysis of tarsiers on agricultural land and
exemplifies the vital role of mixed-species plantations in
conserving wildlife when nearby forest is logged.
S. Merker (&)
Institute of Anthropology, Johannes-Gutenberg University
Mainz, Colonel-Kleinmann-Weg 2 (SB II),
55099 Mainz, Germany
e-mail: [email protected]
genetic characters mostly suggest that they would better be
grouped with monkeys and apes into the suborder Haplorhini (Martin 1990; Schmitz et al. 2001). With head-andbody lengths of about 12 cm, tarsiers weigh little more
than 100 g. These strictly faunivorous primates are endemic to the Greater Sunda Islands (all but Java) and the
Philippines.
Six tarsier species have been described thus far on the
Indonesian island of Sulawesi. Dian’s tarsier (Tarsius
dianae1) occurs in the lowlands and lower montane forests
of Central Sulawesi. This species lives in small groups of up
to seven individuals (Merker 2003). Population densities of
Dian’s tarsier have declined over the past years due to
intensified logging (Merker 2003; Merker et al. 2004). This
finding corroborates previous observations of imminent
threats to other tarsier species (MacKinnon and MacKinnon
1980; Leksono et al. 1997; Gursky 1998). Since the conversion of natural lowland forest into cash-crop plantations
appears to be an almost unstoppable process, assessing the
adaptability of tarsiers to such areas is essential for predicting these animals’ chances of survival.
Thoughts on the interface between tarsier biology and
agriculture are not new. Leksono et al. (1997) found tarsiers
in several cultivated areas of Sulawesi, reported on common
human misperceptions of these animals, e.g., that tarsiers
feed on cash-crops, and even suggested that tarsier populations could be managed as a natural pesticide. They did
not find these primates in areas of intensive coconut farming
but did observe them foraging in a mix of coconut and
cocoa cultivation. There, the animals frequently had sores
on their hands and anogenital regions. Some agricultural
practices inside the natural forest, however, might have
I. Yustian
Department of Biology, Sriwijaya University,
Palembang, Indonesia
1
Shekelle et al. (1997) pointed out this might be a junior synonym to
T. dentatus.
Keywords Cocoa Home range Primates
Radio tracking Tarsius dentatus
Introduction
Deforestation and habitat modification cause the decline of
primate populations around the tropical world (Johns and
Skorupa 1987). In Indonesia, this is not only true for the
large and space-demanding species such as orang-utans,
gibbons or macaques, but also for the lesser-known, smallbodied, and nocturnal tarsiers. These animals were
formerly classified along with lemurs and lorises as prosimians (Simpson 1945), yet anatomical, reproductive, and
123
Primates
desirable effects on tarsiers. Small forest coffee gardens, for
instance, positively affect Dian’s tarsier population densities and ranging patterns (Merker et al. 2004, 2005; Merker
2006).
A common and increasingly important practice in
Indonesia—mostly due to scattered land ownership and
crop rotation—is to cultivate several crop species side by
side. In Madagascar, lemur densities in such mixed-species
plantations are high (Ganzhorn 1987). The study reported
here aimed at revealing the habitat use of Dian’s tarsiers in
such an area in Central Sulawesi, Indonesia. Of particular
importance was the identification of typical vegetation
structures crucial for the presence of tarsiers in this
disturbed habitat.
Methods
From August to October 2001, five tarsier groups were
located in a 25-ha mixed-species plantation close to the
northeastern boundary of Lore-Lindu National Park,
Sulawesi, Indonesia (01°110 50@S, 120°090 26@E, 650–730 m
asl). This plantation comprised cocoa, maize, bamboo, and
the leguminous tree Gliricidia sepium (Jacq.) Steud. mostly
being used as living fence posts, fodder or fuelwood, and
for crop shade and improved fallow. The rhizomatous
perennial grass Imperata cylindrica L. (alang–alang), a
colonizer of degraded humid tropical forest soils, dominated the fallow land between cultivated crops. A patch of
young secondary forest with a canopy height of ca. 10 m
constituted the edge of the plantation towards old-growth
natural forest. Six different vegetation types were mapped
(Fig. 1) using measuring tape and a compass.
Nine tarsiers were captured using mist nets opened at
dusk and dawn in the vicinity of their sleeping sites. Six
adult females (from five groups, Fig. 1) were fitted with
3.3-g radio collars (Holohil Systems, Carp, ON, Canada)
and were subsequently radio-tracked over the course of
2 weeks. The choice of females as focal animals was due to
the design of a more comprehensive research project
comparing tarsier ranging patterns between different habitats (Merker et al. 2004, 2005; Merker 2006).
Data collection comprised shifts in the evening (1800–
2200), in the morning (0400–0630), and full-night follows. Home ranges were estimated by drawing minimum
convex polygons (MCPs) around the outermost data
points (Fig. 1). Since bearings within full-night shifts
were taken every 15 min (every 40 min during the other
shifts), they were likely to be intercorrelated (Merker
2003) and therefore omitted from the analysis described
here. Thus, a total of 32 track points (n = 31 for F5) were
available for each animal to be used in a habitat use
analysis.
123
Fig. 1 Study plot with six different vegetation types, home ranges of
six female Dian’s tarsiers (F1–F6) and commonly used tarsier
sleeping sites
The MCPs were superimposed on the map of vegetation
types (Fig. 1). The percentage of a particular vegetation
type within a tarsier home range was considered as available area. To determine the utilized fragments, data points
were plotted on the habitat map. The proportional use of
vegetation types was calculated by dividing the number of
locations in each fragment by the total number of track
points for this animal. The proportions of available vs.
utilized types were compared using a Wilcoxon signedrank test (Wilcoxon 1945). To test for selection or avoidance of particular structures, Ivlev’s electivity index Ei was
calculated for each vegetation type as Ei = (ui - ai)/
(ui + ai) where ui is the mean proportion of observations in
vegetation type i (habitat utilized) and ai is the mean proportion of vegetation type i available in the tarsier home
ranges (Lechowicz 1982).
Results
Tarsiers avoided fallow land and maize fields and strongly
selected dense shrubbery for sleeping and traveling
(Table 1). Young secondary forest, Imperata cylindrica
grassland, bamboo groves, and cocoa plantations were
Primates
Table 1 Abundance of vegetation types (as a percentage of tarsier home range) and their utilization by six female Dian’s tarsiers (in parentheses, in percent) in a mixed-species plantation in Sulawesi
Vegetation type
F1
Fallow/maize
12.6 (9.4)
Imperata
29.1 (28.1)
Cocoa
26.9 (9.4)
83.1 (71.9)
19.6 (18.7)
91.2 (84.4)
Shrubs
13.5 (18.8)
8.9 (25.0)
24.0 (46.9)
8.4 (15.6)
Bamboo
16.1 (34.4)
16.2 (12.9)
1.9 (0.0)
53.9 (54.8)
Secondary forest
F2
8.0 (3.1)
F3
49.0 (18.8)
F4
F5
0.4 (0.0)
7.3 (15.6)
30.0 (32.2)
F6
Mean
Ei
P
51.4 (25.0)
20.2 (9.4)
-0.37
0.04
4.9 (12.5)
6.9 (9.4)
0.15
0.29
28.8 (31.3)
46.6 (41.3)
-0.06
0.25
15.1 (31.3)
11.7 (22.9)
0.33
0.04
5.4 (7.9)
0.19
0.66
9.3 (9.1)
-0.01
0.66
Ei Ivlev’s electivity index, P for Wilcoxon signed-rank test, F female
Blanks denote the absence of a vegetation type in a particular home range. Mean calculated over all six home ranges, regardless of occurrence of
the vegetation type
neither avoided nor strongly selected. Consistently, tarsiers
utilized multiple kinds of vegetation including cocoa cultivations and Imperata cylindrica expanses. Only one
condition applied to all these observations—dense shrubs,
forest remnants or at least bamboo stands had to be nearby
to provide a suitable sleeping site. According to the land
owners, no insecticides were used but herbicides were
applied in this plot (2, 4-dimethylamine, glyfosate-isopropylamine). However, no unusual incidence of sores on the
hands or the anogenital region of these tarsiers was
detected. Although the tracking period was limited to
2 weeks, the tarsiers were observed over the course of ca.
10 weeks. During this time, the sleeping sites as shown in
Fig. 1 were consistently used, and tarsier ranges did not
change to a degree obvious to the human observer.
As the investigated plot lies in close vicinity to natural
forest (a potential source habitat), it cannot be assessed
here whether tarsier populations farther away from larger
forest patches are able to maintain sufficiently large
populations and gene exchange to avoid inbreeding. In
this particular plot, microsatellite analyses revealed no
reduced allelic variability and no increased relatedness
among these nine tarsiers indicating effective dispersal
(S.M., unpublished data). Follow-up studies including
further genetic analyses as well as a thorough investigation of reproductive success in disturbed areas are needed.
Based on the results of this short study, keeping or creating a mosaic of natural structures (e.g., shrubs, bamboo)
among the cash-crop cultivations as well as a shrub fringe
at the plantation border is recommended. Hedges or tracts
of Imperata cylindrica could effectively link tarsierfriendly plantations.
Discussion
Remnant forest patches or dense shrubbery can render
agricultural land as suitable tarsier habitat. As documented
in a previous study on tarsiers in this mixed-species plantation (Merker et al. 2005), tarsier group sizes are slightly
smaller, and the population density is significantly smaller
than in undisturbed forest. Furthermore, Merker et al.
(2005) found female home ranges to be significantly larger
than in pristine or less-disturbed plots. The authors mainly
attribute this to a reduced insect abundance in the plantations. Body weights, head-and-body lengths, ectoparasite
loads, and group composition were not found to be different between these study sites (Merker et al. 2005).
Although these population parameters indicate more difficult survival under such intensive anthropogenic influence
than in natural forest, such areas could be effective elements of metapopulations and stepping stones or corridors
for gene exchange. When forest is clear-cut, nearby plantations might serve as temporary refuge for a future
re-colonization of the succession areas.
Acknowledgments We wish to thank LIPI, PHKA, POLRI, and
BTNLL for granting research permits; Jatna Supriatna and Noviar
Andayani from UI Jakarta for officially sponsoring the studies; and
Leo, Sapri, and Thony for their help in the field. No animal was
harmed, and all radio-collars were retrieved after tracking. The study
was part of a larger research project supported by the German
Academic Exchange Service and the German National Academic
Foundation.
References
Ganzhorn JU (1987) A possible role of plantations for primate
conservation in Madagascar. Am J Primatol 12:205–215
Gursky S (1998) The conservation status of two Sulawesian tarsier
species: Tarsius spectrum and Tarsius dianae. Prim Conserv
18:88–91
Johns AD, Skorupa JP (1987) Responses of rain-forest primates to
habitat disturbance: a review. Int J Primatol 8:157–191
Lechowicz MJ (1982) The sampling characteristics of electivity
indices. Oecologia 52:22–30
Leksono SM, Masala Y, Shekelle M (1997) Tarsiers and agriculture:
thoughts on an integrated management plan. Sulawesi Primate
Newsl 4:11–13
123
Primates
MacKinnon J, MacKinnon K (1980) The behavior of wild spectral
tarsiers. Int J Primatol 1:361–379
Martin RD (1990) Primate origins and evolution—a phylogenetic
reconstruction. Chapman & Hall, London
Merker S (2003) Vom Aussterben bedroht oder anpassungsfähig? Der
Koboldmaki Tarsius dianae in den Regenwäldern Sulawesis.
PhD Thesis, Georg-August University, Göttingen. http://webdoc.
sub.gwdg.de/diss/2003/merker
Merker S (2006) Habitat-specific ranging patterns of Dian’s tarsiers
(Tarsius dianae) as revealed by radiotracking. Am J Primat
68:111–125
Merker S, Yustian I, Mühlenberg M (2004) Losing ground but still
doing well—Tarsius dianae in human-altered rainforests of
Central Sulawesi, Indonesia. In: Gerold G, Fremerey M,
Guhardja E (eds) Land use, nature conservation and the stability
123
of rainforest margins in Southeast Asia. Springer, Heidelberg, pp
299–311
Merker S, Yustian I, Mühlenberg M (2005) Responding to forest
degradation: altered habitat use by Dian’s tarsier Tarsius dianae
in Sulawesi, Indonesia. Oryx 39:189–195
Schmitz J, Ohme M, Zischler H (2001) SINE insertions in cladistic
analyses and the phylogenetic affiliations of Tarsius bancanus to
other primates. Genetics 157:777–784
Shekelle M, Leksono SM, Ichwan LLS, Masala Y (1997) The natural
history of the tarsiers of North and Central Sulawesi. Sulawesi
Primate Newsl 4:4–11
Simpson GG (1945) The principles of classification and a classification of mammals. Bull Am Mus Nat Hist 85:1–350
Wilcoxon F (1945) Individual comparisons by ranking methods.
Biometrics 1:80–83