Journal of
Threatened Taxa | www.threatenedtaxa.org | 26 August 2018 | 10(9): 12163–12172
Foraging and roosting ecology of the Lesser Dog-faced Fruit Bat Cynopterus
brachyotis (Mammalia: Chiroptera: Pteropodidae) in southern India
T. Karuppudurai 1 & K. Sripathi 2
1,2 Department of Animal Behaviour and
Physiology, School of Biological Sciences, Madurai Kamaraj University, Madurai,
Tamil Nadu 625021, India
2 Present address: Faculty of Allied Health
Sciences, Chettinad Academy of Research and Education, Chettinad Health City,
Rajiv Gandhi Salai, Kelambakkam, Chennai, Tamil Nadu 603103, India
1 tkdurai@gmail.com (corresponding author),
2 sribat@gmail.com
Abstract: The Lesser Dog-faced Fruit Bat Cynopterus
brachyotis was found at higher elevations but since there is a paucity of
reports on its distribution and habitat selection, an inventory was made at
four locations in the Eastern and Western Ghats of southern India where the
elevation ranged from 200–1,500 m. The C.
brachyotis roosts were distributed between 600–1,500 m. Day roosts were found at an elevation of
about 1,000m in Sirumalai and Yercaud Hill stations. Mist-netting studies, however, revealed that C.
brachyotis was widely distributed at different elevations ranging from
600–1,500 m. Moreover, through a
radio-telemetry study, we determined that the males foraged at shorter
distances from the day roost, whereas the females commuted longer distances and
used more than one foraging area. The
male bats’ time of emergence is significantly less than females; in addition,
males frequently return to their day-roost and made several short foraging
flights spaced randomly throughout the night. These observations suggest that
some type of territoriality is associated with their roost, which appears to be
the basis of social organization in C. brachyotis. Overall, this study provides
detailed information about the foraging and roosting ecology of C.
brachyotis in southern India.
Keywords: Cynopterus brachyotis, Eastern
Ghats, Fruit Bat, habitat use, mist netting, radio-telemetry, Western Ghats.
doi: https://doi.org/10.11609/jott.3850.10.9.12163-12172
Editor: Paul Racey, University of Exeter, Devon,
UK. Date
of publication: 26 August 2018 (online & print)
Manuscript details: Ms
# 3850 | Received 16 October 2017 | Final received 06 July 2018 | Finally
accepted 24 July 2018
Citation: Karuppudurai, T. & K. Sripathi (2018).
Foraging and roosting
ecology of the Lesser Dog-faced Fruit Bat Cynopterus brachyotis
(Mammalia: Chiroptera: Pteropodidae) in southern India. Journal
of Threatened Taxa 10(9): 12163–12172; https://doi.org/10.11609/jott.3850.10.9.12163-12172
Copyright: © Karuppudurai &
Sripathi 2018. Creative Commons
Attribution 4.0 International License. JoTT allows unrestricted use of this
article in any medium, reproduction and distribution by providing adequate
credit to the authors and the source of publication.
Funding: Ministry of Environment, Forest and Climate Change
(23/15/2005/RE) and Department of Biotechnology (D.O. NO. BT/HRD/35/02/2006).
Competing interests: The authors declare no competing interests.
Author
Details: Dr.
T. Karuppudurai is a
DBT-Ramalingaswami Fellow (Scientist ‘D’/Senior Assistant Professor) at Madurai
Kamaraj University. His research group currently uses both bats and Drosophila
as model system and his research interest includes bats behavioural ecology,
molecular genetics, molecular biology and Drosophila genetics and molecular
neuroscience. Dr. Sripathi Kandula retired as a Professor at School of
Biological Sciences, Madurai Kamaraj University. He has been working
on the mechanisms of behaviour, conservation and molecular evolution of
chiropterans for more than three and a half decades. Presently he is
working at the Chettinad Academy of Research and Education, Chennai as
Professor and Principal, Faculty of Allied Health Sciences.
Author
Contribution: Study design
(TK and SK); field work, data collection and analysis (TK); photography and
manuscript writing (TK and SK), manuscript correction and revision (TK).
Acknowledgements. This work was supported by grants from the Ministry of Environment and
Forests (MoEF), New Delhi to KS and DBT-Ramalingaswami Re-entry Fellowship
Scheme to TK. We are grateful to Dr.
P.T. Nathan, Dr. T. Karuppanapandian, Dr. S. Baskaran, R. Steffi Christiane,
R. Dhanabalan, S. Sivaraj, C. Sekar, Kumar, C.P. Mayilvaganan and A. Bose
for the assistance rendered. We thank
all the estate owners for permitting us to carry out this study in their coffee
estates and orchards. This work has been
approved by the Institutional Ethical and Biosafety Committee of the Madurai
Kamaraj University, Madurai.
INTRODUCTION
The
Lesser Dog-faced Fruit Bat Cynopterus brachyotis is a group-living,
frugivorous, yinpterochiropteran bat,
distributed throughout Southeast Asia (Corbet & Hill 1992; Bates &
Harrison 1997; Simmons 2015). It is
commonly found at higher elevations of the tropical evergreen forests (Lim
1966; Francis 1994; Balasingh et al. 1999).
In India, it is reported from a few pockets in the Western and Eastern
Ghats (Balasingh et al. 1999). The
behaviours of C. brachyotis such as tent construction (Kunz et al. 1994;
Tan et al. 1997), pollination and seed dispersal (Phua & Corlett 1989),
food habits (Tan et al. 1998) and hind limb motion (Cheney et al. 2014) were
studied in detail and most of the studies had been carried out in the Southeast
Asian countries like Myanmar, Thailand (Bumrungsri & Racey 2007; Bumrungsri
et al. 2007), peninsular Malaysia and the Philippines (Lim 1966; Francis 1994;
Zubaid 1994). The available data suggest
that this is one of the poorly studied species in the Indian subcontinent. Especially, knowledge about distribution,
abundance and habitat selection in southern India is still rather incomplete
and also little is known about their dispersal patterns, sex ratio, breeding
behaviour and social structure. Moreover,
this species is dwindling due to increased human interference so that
traditional roosts have been drastically reduced as a consequence of tree
felling and there is a need for a greater understanding of the species’
occurrence and roosting habits. Therefore,
the main aim of the present study was to evaluate the foraging and roosting
ecology of the Lesser Dog-faced Fruit Bat C. brachyotis in southern
India.
MATERIALS AND METHODS
Study area
We
conducted this study on a monthly basis for a total of 24 months from April
2007 to March 2009 in four different hill regions: Sirumalai (10.19420N
& 77.99670E), Kodaikkanal (10.23810N & 77.48920E),
Megamalai (High Wavy Mountains; 9.64610N & 77.40130E),
and Yercaud (11.77530N & 78.20930E; Fig. 1). The study was carried out at different
elevations ranging between 200m and 1,500m.
In addition, the day roosts of C. brachyotis in Sirumalai and
Yercaud hill regions were surveyed during October and November 2015 and March
and April 2016.
Sampling method (Mist-netting)
Bats
were captured using nylon mist nets of 9m x 2.6m with a mesh size of
38mm (Avinet-Dryden, New York, USA) from different altitudes of the above
mentioned study areas (Image 1). Mist
netting was done from a height of 200–1,500 m.
At each altitude, we mainly concentrated on three locations, which had
most roosting resources and high food resources for bats. Each location was measured approximately
0.1km in diameter and separated by a minimum of 1km from the closest
location. The maximum distance between
the locations was about 5km. Since,
forest fragments were small and limited to areas too steep and inaccessible for
coffee, tea and banana cultivation, it was impossible to find distant capture
locations within fragments in four different hill regions. Every month mist netting was carried over a
period of nearly 24 months. Mist netting
was carried out for 24 nights per elevation (8 nights per location) totaling
168 nights (2,016 night hours) for seven elevations (200–400; 400–600; 600–800;
800–1,000; 1,000–1,200; 1,200–1,400; 1,400–1,500 m) from dusk to dawn. The mist nets were placed away from
illuminated areas to avoid visual detection by bats. Mist nets covered a height of up to 4m from
the ground. They were erected about half
an hour before sunset and removed at 06:00hr.
Mist nets were open all night long (12 hours), under different climatic
conditions, like new and full moon phases and even during rainy nights. The sampling effort was calculated in
net-hours, one net-hour corresponding to one mist net (9x2.6 m, 38mm mesh)
opened for one hour [one 9x2.6 m net open for 1h equal to 1 mist-net-hour
(mnh)]. Each night, we used one net,
resulting in a total sampling effort of 288 net-hours for each elevation,
totally 2,016 net-hours for seven elevations in each hill. In order to identify the relative abundance
of C. brachyotis (excluding recapture) in four different hill regions,
we calculated relative capture rates (number of captured individuals/mist
net-hour) for each hill station. Bats
caught in mist nets were removed immediately with gloved hands and placed in
cloth bags (Gaisler 1973). The
morphological measurements such as body mass and length of forearm were
measured using a spring balance (Avinet-Dryden, USA) and a Vernier caliper,
respectively and also for each bat, species, sex, age were identified, marked
and released (Elangovan et al. 2003); a large number of bats were captured
within a short duration, they were placed in a holding cage to avoid
stress. All the captured bats were
marked with a color-coded bead necklace.
Ten colored beads (5mm) were used for marking the bats with each color
denoting a number from 0–9 (Balasingh et al. 1992). We used three beads for each necklace. Thus, all possible sequential arrangements of
the beads provided up to 999 unique tags.
The necklace was secured around the bat’s neck, by crimping the sleeved
copper ring with long-nose pliers. We
have used this type of tagging for various studies and have observed no
apparent detrimental effects on bats (Gopukumar et al. 2003; 2005; Karuppudurai
et al. 2008). After marking, all
individuals were released at the site of capture. These markings allowed us to identify
individuals and determine their past roosting locations. No bats were injured, killed or retained as
specimens during this study.
Radio-telemetry studies
In addition to mark-recapture studies, a
radio-telemetry study was conducted during September and October 2008 in
Yercaud Hill station. For this study,
four bats (2 females and 2 males) of C. brachyotis were selected within
the study area. The bats were captured
at the time of emergence using mist nets and each bat was fitted with a
transmitter (Model BD-2, Holohil Systems Ltd., Carp, Ontario, Canada). The weight of the transmitter was 1.5g with a
transmission range of 400–500 m, which was mounted over an aluminium collar
covered with reflective tape. The
reflective tape allowed us to locate the bat within the dense foliage using a
torchlight. The transmitter along with
the collar was less than 5% of adult body mass.
Bats fitted with radio collars were released within 3h of capture, but
were not intensely monitored until the following night. Two tracking groups monitored the radio-tagged
bat using Merlin receivers and collapsible 3-element Yagi antennae (Customs
Electronics, Urbana, Illinois, USA).
While, one unit tracked the bat in the foraging area, the other unit
stationed near the day roost monitored the bat activity at the roost. In addition, the activity of the bat at the
roost was observed using a red torch (>640 nm). We rarely lost radio contact with the focal
animal. If radio contact was broken with
a moving bat, contact usually was re-established within 20min by walking
towards the bearing of disappearance. A
change in pulse rate according to the orientation of the antenna allowed us to
determine whether the bat was flying or roosting. The constant beep signals were considered as
‘rest’ and variable singles were considered as ‘flying’. We defined foraging time as the period
between emergence from the roost at dusk and return to the roost at dawn. ‘Foraging bouts’ are defined as the period
during which a bat flew continuously between leaving the roost and returning to
the same roost. The number of foraging
bouts and time spent in the day roost during night hours by male and female C.
brachyotis was analysed by t-tests.
Values are expressed as mean ± SD throughout the text.
RESULTS
Mist-netting studies
Over
the course of mist netting survey at four different hills, a total of 362 C.
brachyotis, were captured (Table 1).
Of the 362 C. brachyotis, about 41 individuals (11.3%) were
recaptured (23 adult females, 11 adult males, five young females, and two young
males). Adult females (56.1%) were
recaptured more frequently followed by adult males, young females and young
males and accounted for 26.8%, 12.2% and 4.9% respectively. In general, more adult females and males were
recaptured at nearby elevations but occasionally adult females were recaptured
in distant elevations than males. For
example, in Kodaikkanal hill station, one tagged adult female was captured at
an elevation of 1,400–1,500 m but was originally captured and tagged at an
elevation of 800–1,000 m.
Among
the four different hills, the Sirumalai hill region accounted for 22.4%, of
bats, the Kodaikkanal hill station accounted for 28.2% of bats, the Megamalai
(High Wavy Mountains) accounted for 26.2% and Yercaud accounted for 23.2% of
the total bats (Table 1). There was no
significant difference found among the total number of C. brachyotis
captured at different elevations in four different hill stations (ANOVA:
F3, 24 = 0.08, P = 0.97), and also there was no
significant difference among the total C. brachyotis mark-recaptured at
four different hill stations (ANOVA: F3, 24 = 0.33, P
= 0.80). To identify the abundance
of C. brachyotis (excluding recapture) in four different hill stations,
we conducted a total of 2,016 mist-net-hours in each hill station. In Sirumalai Hill station a total of 81 C.
brachyotis were captured with a capture rate of 0.040 bats per
net-hour. In Kodaikkanal Hill station a
total of 102 bats were captured, which corresponds to a capture rate of 0.051
bats per net-hour, in Megamalai a total of 95 bats were captured, with a
capture rate of 0.047 bats per net-hour and in Yercaud 84 bats were captured,
which corresponds to a capture rate of 0.042 bats per net-hour.
In
addition, a total of 229 bats of another three species were captured. All species captured were common bats (Table
1). Two species of fruit-eating bats, Cynopterus
sphinx (218), Rousettus leschenaultii (9), and one species of
insect-eating bat Megaderma spasma (2).
Our study species C. brachyotis accounted for 61.3% of all bats
captured. Other three bat species C.
sphinx, R. leschenaulti and M. spasma, accounted for 38.7%,
1.5% and 0.3%, respectively. Overall,
members of the C. brachyotis (61.3%) and C. sphinx (38.7%) were
captured most frequently (Table 1).
There was no significant difference among the total bats captured at
four different hill stations (ANOVA: F3, 12 = 0.27, P
= 0.84).
Distribution, abundance and roosting
ecology of C. brachyotis
The
distribution and abundance of C. brachyotis survey was carried out at
different elevations starting from 200–1,500 m.
More C. brachyotis were captured and observed in higher
elevation (600–1,500 m; Fig. 2) and stayed only in higher elevations in
southern India. In contrast, the C.
sphinx was captured both in higher and lower elevations but the capture
rate was lower in higher elevation and higher in lower elevation. We distinguished C. brachyotis from C.
sphinx on the basis of four morphological characters like forearm length,
body mass, ear length and pelage colour (Image 1). The mean forearm length (61.6±1.7 mm) and
mean body mass (32.3±2.5 g) of C. brachyotis were significantly lower
than the mean forearm length (68.5±2.2 mm) and body mass
(47.2±3.8 g) of C. sphinx (forearm length of C. brachyotis vs. C.
sphinx; t = -23.902, P<0.05; body mass of C. brachyotis
vs. C. sphinx; t = -19.852, P<0.05). The mean ear size of C. brachyotis (16.9±0.72
mm) was significantly smaller compared with mean ear size of C. sphinx (20.2±1.1
mm; t = -15.041, P<0.05).
The dorsum of C. brachyotis is cinnamon brown compared with the
darker olive black of C. sphinx (Image 1).
The day
roosts of C. brachyotis were located at an elevation of above 1,000m in
Sirumalai and Yercaud hill stations (Image 2).
In these study areas, C. brachyotis constructed tents in the
pepper plant (Piper nigrum L.), leaves of banana tree (Musa acuminata)
and in the cavities of Indian Banyan tree (Ficus benghalensis) which
were observed. At Yercaud, a day roost consisting of 10 C. brachyotis were
found in the roof of an abandoned building (Image 2f). Recent direct
observation of day-roosts revealed that C. brachyotis completely abandon
the pepper plant (P. nigrum L.) and leaves of banana tree (M.
acuminata) tents. The cavity of
Indian Banyan tree (F. benghalensis), however, was still used as a day
roost.
Radio-telemetry studies
In the
radio-telemetry study, four bats (2 males and 2 females) were radio-tagged in
order to estimate the number and type of foraging areas used by C.
brachyotis (defined as the localities within which bats were found,
presumably feeding, during a large proportion of the night) and patterns of
nightly behaviour by individual bats.
Each locality has different habitats interspersed with coffee
plantations, orange groves, pepper plants and banana trees and the localities
are separated from the day roosts by one kilometer. The male (M1 and M2) and female (F1 and F2)
bats were successfully tracked for 16, 10, 5 and 14 days respectively and their
day roosts were also located successfully (Image 3). The female bat (F2) was roosting in the
pepper plant (P. nigrum L; Image 3a,b) and the male bat (M1) was
roosting in the banana tree (M. acuminata; Image 3c). Interestingly, the
male bats used a maximum of three night roosts.
Conversely, the female bats used a maximum of two night roosts. All the male bats used a single day roost and
female bat F1 used a single day roost while female F2 used 2-day roosts (Table
2). The male bat returned to its day roost (modified leaves of banana tree)
regularly, however, female bats changed their day roost frequently to either
pepper plants and/or a cavity in an Indian banyan tree. The male and female bats used 5 and 6
different foraging areas, respectively (Table 3). The foraging site one was used exclusively by
male bats and site 6 was used exclusively by female bats. The male bats foraged ca. 4–4.5 km and the
female bats foraged 5–6 km from the day roosts.
Female bats travelled longer distances and used more foraging areas
(Table 3).
The
male and female bats foraged at different areas. Throughout the study, male bats made many
visits to its day roosts and thus it spent significantly less time in
foraging. There was significant
difference in the mean number of foraging bouts/night between male (7.6±1.1)
and female (2.2±0.8, n=5 nights) bats (t = 6.65, P<0.05; Fig.
3) and also there was significant difference in the mean time spent in the day
roost/night between males (223±80.7 min) and females (554±100.2 min, n=5
nights) (t = 4.97, P<0.05; Fig. 4).
DISCUSSION
Diversity and richness of C. brachyotis
in southern India
Our
study provides detailed information about the distribution, abundance and
number of foraging areas of C. brachyotis in peninsular India. Day roosts of C. brachyotis were
located at an elevation of about 1000m and distributed at different elevations
that ranges from 600–1,500 m in all selected hill stations to avoid biotic and
abiotic disturbance (Brooke et al. 2000; Baskaran et al. 2016). These observations, suggest that C.
brachyotis occur at higher elevations in southern India, whereas, in
Southeast Asia C. brachyotis prefers to stay in the plains (Kunz et al.
1994; Tan et al. 1997). In contrast, the
Indian Short-nosed Fruit Bat C. sphinx were captured both in higher and
lower elevations but the capture rate of C. sphinx was lower in the
higher elevation. Most fruit bats are
known to play a crucial role in reforestation through seed dispersal. Previous studies showed that C. brachyotis
modified leaves of palm trees to construct tents which were then used as day
roosts and/or feeding roosts (Tan et al. 1997).
In this study, we observed that C. brachyotis modifies the pepper
plant, leaves of the banana plant, and also used cavities in the Indian banyan
tree as day roosts (TK-personal observation).
Our recent day roost observations clearly revealed that modified pepper
plant and banana tree roosts were completely abandoned by C. brachyotis
in Sirumalai and Yercaud hill stations.
The reasons for decrease in the bat population and roost sites appear to
be increased human interference by way of cultivation. Traditional roosts have been drastically
reduced as a consequence of tree felling (TK-personal observation).
Feeding behaviour
Previous
studies suggest that the fruit bat C. brachyotis feeds on fruits of 54
plant species, leaves of 14 species and the stamens of four species. Its role as a seed disperser has been
documented in other Southeast Asian countries (Marshall 1983; Phau &
Corlett 1989). In the present study, we
observed that C. brachyotis mainly feed on several fruits, especially
banana, jackfruit, orange and coffee.
The feeding roosts were usually within 100m of the fruiting tree. Occasionally fruits were carried too far (2–3
km). In our study areas, the most
favoured day-roost in the hills was the pepper plant, which sometimes supported
colonies of 10 or more bats. In our
field studies, most of the mist-netted bats were C. brachyotis flying at
2–5 m from the ground. The foraging
pattern was observed indirectly from the rate of capture at every hour from
dusk to dawn by mist netting. The peak
foraging activity occurred between 21:30–23:00 hr with a small peak at
04.30–05.30 hr showing a dominant unimodal pattern of foraging activity in C.
brachyotis. The second small peak
cannot be considered as foraging activity as it may represent a return from the
foraging areas. Generally, bimodal
activity patterns are characteristic of almost all insectivorous species and
some fruit eating bats (Fleming 1982; Elangovan et al. 1999; Stephenraj et al.
2010). In contrast, unimodal patterns
are dominant among frugivorous and nectarivorous species (Fleming & Heithaus 1986). From our indirect observations, the unimodal
pattern of foraging activity was observed in C. brachyotis, however,
further systematic studies are required to determine the pattern of foraging
activity.
Roosting Ecology
Radio-telemetry
studies showed that bats left their day roosts shortly after sunset and flew to
foraging areas while they began to search for ripe fruits. The harvested fruit is transported to the
night roost for consumption. These
‘night roosts’ might promote digestion and energy conservation, offer retreat
from predators, serve as centers for information transfer about the location of
fruit patches and facilitate social interaction (Morrison 1978; Kunz 1982; Fleming
1988). Throughout our study one male bat
was found to have high night roost fidelity.
A banana tree was used as a night roost constantly. The regular travel path exhibited by this bat
between its day roost and foraging area may be attributed to the constancy of
resource availability. Such trap-lining
behaviour (repeated sequential visits to a series of feeding or foraging
locations) minimizes commuting search distance and energy cost. But the other tagged bats of both sexes used
more than one night roost. High risk of
predation may be attributed for the usage of more night roosts. It seems clear that male C. brachyotis
restrict their foraging areas close to the day roost, whereas, females commute
longer distances and utilized several foraging areas. Since, the male is involved in tent
construction, harem formation, and defense, a foraging area a short distance
away would facilitate harem defense strategies near the day roost (Fleming
1988). These observations of short
distance foraging flights of males are consistent with the earlier reports on
the activity of harem males in C. sphinx, Artibeus jamaicensis,
Phyllostomus hastatus, Carollia perspicillata, and Balionycteris
maculata (Morrison 1978; Fleming 1988; Balasingh et al. 1995; Bhat &
Kunz, 1995; Marimuthu et al. 1998; Gopukumar et al. 1999; Hodgkison et al.
2003; Karuppudurai et al. 2008). This
suggests that some type of territoriality is associated with shelter, which
appears to be the basis of social organization of bats (Kunz et al. 1998).
Foraging behaviour of male and female
C. brachyotis
Female
bats travel long distances (ca. 6km).
Besides, they change their primary foraging area in an unpredictable
fashion as observed in C. perspicillata (Kunz 1982). Since not every foraging area contains the
same potential food resources, one reason for such unpredictable ‘shuttles’
might increase dietary diversity. The
foraging areas of females are isolated whereas the foraging areas of males are
overlapping. Since the day roost of most
of the males lie within a rich food patch, overlapping of foraging areas is
likely to arise (our unpublished data).
The exact reasons why female C. brachyotis commute longer
distances, spend more time foraging and utilize several foraging areas are not
clearly known. One of the reasons for
long distance commuting by females might be searching for potential male tent
roosts and to assess the harem male’s parental ability. Recent studies reported the importance of
female choice especially in highly mobile animals with harem mating systems
(Clutton-Brock 1989; McComb 1991).
Female Saccopteryx bilineata actively select their roosting
location and are highly mobile; some females shift roosting territories during
the course of a day and some disperse to other colonies (Heckel et al.
1999). In addition, earlier studies in C.
sphinx reported fluctuations in the harem size on a day-to-day basis,
indicating that females periodically shifted their tents (Balasingh et al.
1995; Karuppudurai & Sripathi 2010).
Similarly, the polygynous bats A. jamaicensis (Ortega et al.
2003), P. hastatus (McCracken & Bradbury 1977), Desmodus
rotundus (Wilkinson 1985), and S. bilineata (Heckel et al. 1999)
shifted their roosting sites. Our
radio-telemetry studies lend support to these observations. In the present study, one female bat used
more than one day roost and also shifted her day roosts frequently. Overall, male and female C. brachyotis
differed in their foraging areas and behaviour, as it has been shown for many
other bat species like Rousettus aegyptiacus (Barclay &
Jacobs 2011), Myotis daubentonii (Ngamprasertwong et al. 2014),
and Nycticeius humeralis (Istvanko 2015). An extension of molecular genetics techniques
to behavioural ecology might help in understanding the behavioural ecology of C.
brachyotis. For example, how the behavioural phenotypes are controlled by
genes, how they interact with other genes, what is the molecular and genetic
basis of their allelic variation, and how this variation behaves with respect
to the environment.
CONCLUSION
The
present study describes the distribution, relative abundance and number of
foraging areas of C. brachyotis in four different hill stations in the
southern Western Ghats. These findings
provides additional knowledge of the behavioural ecology of fruit bats in the
Western Ghats, southern India in order to improve habitat suitability models,
define critical habitat, and direct land management policies. There is little information about this
species in the Indian subcontinent especially in the Western Ghats. Hence, this study provides detailed
information about the habitat selection of C. brachyotis and is useful
in bringing out new information about this species and also gives more
information about the altitudinal preference and plant animal
interaction in the forest area. The
understanding of habitat selection of C. brachyotis can contribute
valuable guidelines for proper conservation and management and is also helpful
for formulating bat conservation strategies.
Further studies, however, are needed to determine the dispersal
patterns, sex ratio, mating strategy and genetic diversity of C. brachyotis
over the long term using behavioural and molecular techniques.
Table 1. Total
number of C. brachyotis and other bat species captured at four different
hill stations in southern Western Ghats. Value in parentheses is percentage (%)
of bats captured in each species.
Study areas / Bat species |
Sirumalai (1,600m) |
Kodaikkanal (2,133m) |
Megamalai (1,500m) |
Yercaud (1,623m) |
Total number of bats |
C. brachyotis |
81 (22.4) |
102 (28.2) |
95 (26.2) |
84 (23.2) |
362 (61.3) |
C. sphinx |
107 (49.1) |
86 (39.4) |
14 (6.4) |
11 (5.0) |
218 (38.7) |
R. leschenaulti |
3 (33.3) |
4 (44.4) |
2 (22.2) |
0 (0.0) |
9 (1.5) |
M. spasma |
0 (0.0) |
0 (0.0) |
2 (100) |
0 (0.0) |
2 (0.3) |
Table 2. Tracking summary of radio
collared male and female bats of C. brachyotis in Yercaud Hill region.
Bat code |
Observed days |
No. of day roosts used |
No. of night roosts used |
Cause for end of observation |
M1 M2 F1 F2 |
16 10 5 14 |
1 1 1 2 |
3 1 2 1 |
Transmitter recovered Transmitter loss Transmitter loss Bat disappeared |
Table 3. Number of foraging areas used
by radio tagged bats in the study area. Value in parentheses is
distance(s) to foraging areas from the day roosts (km).+ used; - not used
Bate code |
No. of Foraging areas
1 2 3 4 5 6 |
|||||
M1 M2 F1 F2 |
+ (0.2) + (0.1) - (0.8) - (1.0) |
+ (0.6) + (0.8) - (1.0) + (1.2) |
+ (0.9) + (0.4) + (0.5) + (0.8) |
+ (1.2) + (1.1) + (1.5) - (2.0) |
+ (2.0) - (2.4) + (2.8) + (3.0) |
- (4.0) - (4.5) + (5.2) + (6.0) |
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