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MN265 Spatial Ecology, Behaviour and Responses to Anthropogenic Disturbance of
Lemurs in Mahamavo Dry Forests, Madagsacar
Prof. Dr. Ute Radespiel, TiHo Hanover/Germany
Dr. Kathy Slater, Operation Wallacea
Within the Mahamavo forests of Western Madagascar there are numerous opportunities to
study the species of lemur that occur there. The research opportunities can broadly be divided
into two areas that focus on (1) the effect of anthropogenic habitat disturbance and human
settlements on lemur ecology and behaviour and (2) the spatial ecology and feeding behaviour
of Coqeuerel's Sifaka. Students booking on to this research project will be able to design their
proposal around either of these two lines of enquiry based on the project summaries below.
Study Site
The project will be conducted in the Mahamavo area in northwestern Madagascar, close to the
village of Mariarano. The habitat in this area is a matrix of wetlands and dry forest. The dry
deciduous forest fragments of the area vary in size and surround the camp sites (Figure 1). Up
to eight lemur species can be found in the fragments but their spatial distribution and local
abundance in the fragments may vary. Various forest trails and a systematic grid system in the
area allow access to the forest and will be used for systematic data collection.
a) forest / non-forest
b) patch area
Figure 1: Maps of Mahamavo protected area showing forest patches in terms of forest versus nonforest (a) and forest patch area (b). Forest patch area was calculated using the distance of every
forested pixel from the forest edge, the perimeter:area ratio of every forest patch (a measure of
compactness), and the distance to the edge of the nearest neighbouring forest patch (a measure of
isolation). Both maps were prepared by Dr Peter Long from Oxford University.
1) The effect of anthropogenic habitat disturbance and human settlements on lemur ecology
and behaviour, Madagascar
The high level of deforestation that has occurred on Madagascar over the past century is a
primary conservation concern. The constant loss of forest habitats coincides with an increasing
degree of forest fragmentation, and the rather small geographic distributions of many lemur
species. In addition, remaining forests are often altered by selective logging or wood
extraction, and many lemur species are still locally hunted (Mittermeier et al. 2010).
In this situation it is of utmost importance to understand the ecological plasticity and
responses of each lemur species towards these anthropogenic threats. This knowledge is
needed to understand the ecological vulnerability of each species and to develop and
formulate expert recommendations for effective conservation measures. It is known that
anthropogenic disturbances such as habitat fragmentation, selective logging or hunting can
modify habitats and alter the community structure and behavioural ecology of free-living
animal populations considerably (Henle et al. 2004). However, it is also known that not all
lemur species respond equally to forest fragmentation (Lehman et al. 2006). Extant Malagasy
lemurs have very diverse ecological requirements (microhabitats, sleeping sites etc.), activity
patterns (nocturnal, diurnal, cathemeral), feeding habits (folivores, frugivores, omnivores),
body sizes (40g - 9.5kg) and social organisations, and the interactions between these
parameters and the long-term viability of lemur populations in fragments is still largely
underexplored. The intensity of habitat disturbances typically correlates with the access of
humans to an area. Spatial proximity to the next human settlements and to forest edges can
be a good approximation for these potential threats.
A total of eight lemur species are known from the Mariarano area, six of which are nocturnal
(Microcebus murinus, M. ravelobensis, Cheirogaleus medius, Phaner pallescens, Lepilemur
edwardsi, Avahi occidentalis) and two are diurnal or partly cathemeral species (Eulemur fulvus,
Propithecus coquereli) (Olivieri et al. 2005, Mittermeier et al. 2010). Five of them are
categorized as endangered since the most recent IUCN assessment (IUCN 2012). The eight
species vary in all above mentioned traits and therefore form an interesting subset of species
to explore the effects of habitat fragmentation on species with different life styles and life
histories. Species can be expected to alter their ecology but also their behaviour in response to
human interventions of various kinds. For example, individuals may show different feeding
strategies or group sizes, or they may differ in locomotion, vigilance, or flight responses
towards human observers in varying distances to forest edges and settlements.
The aim of this study is to explore the influence of varying proximity to human settlements and
forest edges on the abundance and behaviour of different lemur species occurring in the
Mahamavo region of northwestern Madagascar. Particular emphasis shall be given to
nocturnal species (Microcebus spp., Lepilemur edwardsi), as they are generally less studied
than their diurnal cousins but not necessarily less vulnerable.
Data Collection
Data on the spatial distribution of lemurs species are typically collected with nocturnal or
diurnal very slow survey walks (Durckworth 1998) which need to be complemented with
capture-mark-release sessions in the case of mouse lemurs (Microcebus spp.), since the two
sympatric species cannot be easily distinguished during nocturnal surveys (Rakotondravony &
Radespiel, 2009). During a systematic survey walk, lemur encounters are always documented
for each species by with a GPS-device, and complementary data can be simultaneously
collected on the used microhabitats (e.g. substrate, height above ground), group size, and/or
behaviour (e.g. locomotion, feeding, flight response) that will allow the test of specific
hypotheses. Each survey walk will take between 2-3 hours depending on trail length (1-1.5km)
which should have a perpendicular orientation to the forest edge. The remaining time of the
day can then be used for data entry and analyses of the GIS-based dataset and edgedependent behavioural responses.
Mouse lemur capture sessions are typically performed overnight with the help of Sherman Live
Traps that are baited with banana and checked in the early morning. The installation of traps
at varying distance from forest edges and human settlements will allow testing the influence of
these two parameters on mouse lemur abundance. Captured mouse lemurs will be marked,
sexed, and assigned to their respective species. They can furthermore be measured
morphometrically in order to obtain physical data on body size, body dimension or body
condition that may be relevant for certain questions. All mouse lemurs will be released at their
individual capture sites at dusk. Capture data will allow to determine species-specific
abundances and edge responses of both species in a comparable way.
Survey walks can also be combined with the method of focal animal sampling (Altmann 1974)
in order to obtain more extended behavioural datasets for a particular lemur species.
Encountered but individually unknown individuals of that species can be followed and
observed continuously until contact is lost. The interrupted survey walk will subsequently be
resumed up to the next encounter, which will mark the beginning of the next episode of
behavioural observations. By employing this mixed approach, larger behavioural datasets can
be obtained without actually marking the animals or knowing them individually. These
modified survey walks will typically be conducted over half nights or half days.
Mouse lemurs (Microcebus spp.) can also be observed individually by employing the method of
radio-tracking which is always preceded by a period of capturing. Some captured individuals
can then be radio-collared and will subsequently be released at their respective capture sites.
The observer can then collect individual-based datasets on a defined number of individuals on
space use (home range sizes), sleeping sites, or other behaviours in varying distance from
forest edges and human settlements. Nocturnal focal observations will typically be conducted
over half nights.
Depending on the topic that is chosen and developed within this framework of fragmentation
effects, some of the above mentioned methods can be combined and conducted in parallel in
study sites that differ in their proximity to forest edges and human settlements.
2) Feeding ecology, habitat preferences and activity budgets of Coquerel’s Sifaka,
Madagascar
Coquerel’s Sifaka (Propithecus coquereli) is a medium sized lemur with a total length of 93110cm and weight of 3.7-4.3kg (Rambinintsoa et al., 2006). They are diurnal and live in
extended family groups of 2-10 individuals (Rambinintsoa et al., 2006; Mittermeier et al.,
2010). This species is primarily folivorous, but are also known to eat flowers and fruits when
available (Richard, 1978; Mittermeier et al., 2010). Their diet includes up to 98 different plant
species (Richard, 1978), but they show a significant preference for leaves high in extractable
protein and low in acid detergent fibre (Ganzhorn, 1992). These “high quality” leaves occur at
significantly higher densities in dry deciduous forest than in evergreen forest (Ganzhorn,
1992). Feeding is often in a suspensory posture (Mittermeier et al., 2010).
Coquerel’s Sifakas are most active in the morning and late afternoon, and travel between trees
by leaping often large distances from trunk to trunk and occasional bipedal hopping similar to
a kangaroo (Mittermeier et al., 2010). They favour gallery forest, but can be found in a range of
habitats including degraded forests and small forest fragments (Mittermeier et al.,
2010). However, detailed studies of their behavioural and dietary adaptations to forest
fragmentation and degradation are lacking.
Coquerel’s Sifaka have one of the most restricted ranges of all the lemurs and are only found in
the lowland dry forests of north western Madagascar. Listed as an IUCN endangered species,
these lemurs are severely threatened by habitat loss and hunting. For local tribes in the region
it is taboo to harm the lemurs, but recent immigration had lead to hunting of Coquerel’s Sifaka
in some areas. There are only two protected areas where Coquerel’s Sifaka are known to
occur: the Ankarafantsika National Park and the Bora Special Reserve. Unfortunately there is
significant hunting pressure on this species in Ankarafantsika and the forest in Bora has
become considerably degraded. Coquerel’s Sifaka are also found in forests outside these
protected areas. Community based conservation projects in these areas are therefore
extremely important for the survival of this species.
The aim of this project is to investigate the ranging, habitat preferences, feeding ecology, and
activity budgets of Coquerel’s Sifaka in the Mahamavo region of north western Madagascar,
close to the village of Mariarano. These data will provide vital information relating to the
species behavioural and dietary adaptations when living in forest fragments. The data will also
be useful for the community management of the area by improving the understanding of the
ecological needs and impacts of habitat disturbance on Coquerel’s Sifaka.
Data Collection
In order to investigate activity budgets, data is needed from dawn until dusk. However, such
long days does not leave sufficient time for data entry and addition data collection such as
habitat assessments. Depending on the ease with which the lemurs can be encountered and
the length of time they can be followed each day, behavioural observations will either be
conducted from dawn until dusk with occasional full days where the lemurs are not observed
to allow time for data entry and other data collection, or in morning (dawn till midday) and
afternoon sessions (midday till dusk) leaving half-day sessions for data entry and other data
collection. The GPS location of the group will be recorded throughout the day in order to
assess home and day range. Upon locating a group, the number or individuals and age-sex
classification of each will be recorded.
Activity data will be collected using instantaneous scan samples (Altmann 1974). You will need
to decide on the interval for these scans, either 3, 5, or 10 minute intervals. If you can easily
scan the group and record data for each individual within 1 minute, then 3 minute intervals are
fine, but if it takes you longer to do this (due to visibility issues or because group members are
often spread out) then you need to increase the interval to 5 or 10 minutes to ensure that
each scan is independent of the other. For each scan you should record the behaviour
(feeding, moving, resting, social, vigilant etc) of each adult individual in the group using a predefined behavioural ethogram. When feeding, the type of food (mature leaves, young leaves,
fruit, flowers and bark), and corresponding plant species will be recorded where known.
Where plants can not be identified in the field, photographs and samples will be taken for later
identification. For each scan, the habitat type, predominant plant species, and weather
conditions can be recorded.
Additional data can then be collected in order to interpret the findings of the activity and diet
data. Habitat surveys could be conducted to investigate forest structure, woody plant
composition and to ascertain the level of forest disturbance. Habitat data could be collected
using 20m x 20m plots in which the major woody plants are identified, DBH is measured,
canopy cover is measured using canopy scopes and evidence of anthropogenic disturbance is
recorded. Alternatively, habitat preferences could be investigated by uploaded ranging
patterns of the lemurs obtained from GPS units onto existing GIS vegetation maps of the
reserve. It may also be possible to investigate how Sifakas adapt their behaviour and diet
according to characteristics of the forest fragments in terms of patch area and distance to
other fragments.
References
Altmann, J. 1974. Observational study of behaviour: sampling methods. Behaviour 49: 227267.
Duckworth. J.W. 1998. The difficulty of estimating population densities of nocturnal forest
mammals from transect counts of animals. Journal of Zoology, London 246: 466-468.
Ganzhorn, J. U. (1992). Leaf chemistry and the biomass of folivorous primates in tropical
forests. Test of a hypothesis. Oecologia 91: 540–547.
Henle, K., Davies, K.F., Kleyer, M., Margules, C., Settele, J. 2004. Predictors of species sensitivity
to fragmentation. Biodiversity and Conservation 1: 207-251.
Lehman S.M., Rajaonson, A. & Day, S. 2006. Edge effects and their influence on lemur density
and distribution in southeast Madagascar. American Journal of Physical Anthropology 129:
232-241.
Mittermeier, R.A., Louis Jr, E.E., Richardson, M., Schwitzer, C., Langrand, O. Rylands, A.B.,
Hawkins, F., Rajaobelina, S., Ratsimbazafy, J., Rasoloarison, R., Roos, C., Kappeler, P.M. and
Mackinnon, J., Illustrated by Nash, S.D. (2010). Lemurs of Madagascar: Conservation
International Tropical Field Guide Series, Third Edition. Conservation International:
Arlington, VA, USA.
Olivieri, G., Craul, M. & Radespiel, U. 2005. Inventaire des lémuriens dans 15 fragments de
forêt de la province de Mahajanga. Lemur News 10: 11-16.
Rakotondravony, R. & Radespiel, U. 2009. Varying patterns of coexistence of two mouse lemur
species (Microcebus ravelobensis and M. murinus) in a heterogeneous landscape. American
Journal of Primatology 71: 928-938.
Rambinintsoa, A., Rigobert, Z.J., Richar, R., Razafindraibe Jean François Xavier, R.J.F.,
Brenneman, R.A. and Edward E. Louis Jr, E.E. (2006). A preliminary study on resident lemur
populations in the Mariarano Classified Forest. Lemur News 11: 21-24
Richard, A.F. (1978). Behavioral Variation: Case Study of a Malagasy Lemur. Bucknell University
Press: London.