Article Citation: Ezhilmathi Sophia

Dwindling Populations of the Microchiropteran Bat, Hipposideros ater (Hipposideridae: Chiroptera) in Tirunelveli Journal of Research in Ecology (2015) 2(3): 018-026

Dwindling Populations of the Microchiropteran Bat, Hipposideros ater

(Hipposideridae: Chiroptera) in Tirunelveli

Keywords: Hipposiderid bat, bio-control agent, human interference, population decline.

018-025| JRE | 2015 | Vol 2 | No 3

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Journal of Research

in Ecology An International

Scientific Research Journal

Authors:

Ezhilmathi Sophia

Institution:

PG and Research

Department of Zoology, St.

John's College,

Palayamkottai-627002 ,

Tamil Nadu, India

Corresponding author:

Ezhilmathi Sophia

Email Id:

Web Address: http://eologyresearch.info/

documents/EC0029.pdf.

Dates: Received: 20 Dec 2013 Accepted: 25 Sep 2014 Published: 12 Feb 2015

An International Scientific Research Journal

ORIGINAL RESEARCH

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ABSTRACT: Being a tropical country, India has a wide variety of bat fauna. Bats are one of the unrecognized species of mammals; in spite of their vital role in the maintenance of the agro and forest ecosystem. The dusky leaf-nosed bat, Hipposideros ater is a smaller, shy and sensitive bat species. A continuous monitoring of the H. ater colony for a period of 12 year in Tirunelveli, South India, reveals that they are highly sensitive and show high fluctuations with sharp decline in the population size mainly due to human intrusions, particularly during breeding seasons. It is recommended that this bat species may be conserved as it is a bio-control agent, by protecting their roosts as well as by constructing bat houses in undisturbed areas.

INTRODUCTION

There are 1,242 species of bats in the world and

India has 114 species among them (IUCN 2003). But

25% of the Indian bat population comes under the

Threatened and 1% under the endangered species

respectively. Significantly, Hipposidrid bats are effective

bio control agents which mainly feed on the agricultural

pests and mosquitoes.

Generally, the Chiropterans are highly sensitive

and vulnerable to disturbances and hence they choose

roost in accordance to their sensitivity. Disturbance to

roosts leads to decline in bat population and exert

enormous pressure on the food chain. Hence their

conservation and management must be considered as an

essential element to bring sustainable development both

in agro-ecosystem and tropical ecosystem (Fujita and

Tuttle, 1991).

Bats enjoy diversified roosts such as caves,

trees and anthropogenic structures which provide spots

for mating, venue for rearing young ones, a community

hall for social promotion and a refuge from adverse

weather and predators (Kunz, 1982). In India, natural and

manmade habitats are used as roosts by these bats which

are under threat and not protected. Bats generally spend

most of their time in such day roosts. Deforestation and

urbanization has been increased at an alarming rate is the

main threat to the bat roosts.

One such microchiropteran bat facing this severe

threat is the Dusky leaf nosed bat, Hipposideros ater.

The major threat to almost all bat species in India is

habitat loss (Jeya Prabha and Vanitharani, 2003).

Changes in habitat, habitat destruction, deforestation,

looping of trees, construction of dams, human

settlements, urbanization and break down of old

buildings are the major calamities faced by the Indian

tropical bats. H.ater is very sensitive and the colony is

easily disturbed and they even die when the spelunkers

visit the colony during their breeding season.

MATERIALS AND METHODS

Study Animal

H.ater is a smaller hipposiderid bat with a nasal leaflet,

and a pale grey fur on its body (Fig. 1). It is distributed in

Australia, India, Indonesia, Malaysia, Myanmar, Papua

New Guinea, the Philippines, Sri Lanka and Thailand. It

is very delicate and shy but an active individual avoiding

mist net. They show bimodal reproductive cycle

correlating with monsoon prevailing in their roosting site

(Gopalakrishnan and Madhavan, 1978). Even a slight

disturbance might force them to evacuate their diurnal

roost. The habitat in which these roosts of H.ater located

happens to be generally covered by water bodies and

paddy fields. Some roosts are engulfed by human

habitation with heavy traffic illuminated by sodium

vapour lamps during nights (Fig. 2).

Methodology

The present study is an attempt to survey the

roosts of H.ater in and around Tirunelveli (08o 44’ N;

77o42’E) from 2001 to 2012. The oral enquiries in the

study area have provided information on the available

roosting sites. Without disturbing the colony total

number of individuals was recorded by visual count. The

location, nature of roost and light pattern were also noted

along with the common threats faced by the colony.

For the convenience of continuous monitoring,

one roost located in an urban habitation was selected and

the bats were mist netted to record the colony

composition (Fig. 1). The location is Tirunelveli

Junction, (Tamil Nadu) in which one finds a tSophia

inker workshop. (plate 1)The population size was

calculated by Cloudsley-Thompson (1980) method.

RESULTS

Survey on roosting sites of Hipposideros ater was

carried out in and around Tirunelveli, continuously for

12 years, during the months of June and December from

2001 to 2006 and on every June from 2006 to 2012. The

colony size was recorded by visual count in 8 different

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019 Journal of Research in Ecology (2015) 2(3): 018 – 026

roosting places. The results reveal that this bat species

roosts in unused buildings including kitchen, godown,

dungeon room, stone buildings, community hall etc. The

sites of the roost locations include middle of human

habitation within city limit and agricultural surroundings

within village limit. The lighting pattern includes from

dark to semi-dark conditions. The population size of the

bat species ranges from one to 300 individuals. The

threats posed mainly by human interference through

renovation and fumigation (Table 1). Table-2 shows the

colony size, sex ratio and other information with regards

to the colony members at an unused workshop from 2001

to 2005.There was a steady decline of bat population

throughout the study period (Fig 1). For instance, in the

roost # 4, the bat population was 150 in the beginning

and 5 at the last visit, similarly in roost # 8, the

population was 300 during June 2004 and it was 35 at the

end of the study. It is also observed that a few symbiotic

bat species like Hipposideros speoris and Megaderma

lyra inhabits the roosts of H. ater, as intruders.

DISCUSSION

The survey of H. ater colony during the study

period and the colony composition reflects high

fluctuation leading to a sharp decline in population. The

selection of roost is a vital part to maintain the

population, as the roost is a spot for mating and venue

for rearing the young ones. The day roosts mainly offer

protection from predators and adverse weather

conditions. Significantly bats may also change roosts on

seasonal basis, favouring their mating, rearing young

ones and other activities (Lewis, 1995). They quite often

use different kinds of roosts because predation and

human interference to roosts are threats for their survival

(Kunz, 1982). H. ater chooses only dark and humid area.

It is recorded that all the roosts are under stress due to

renovation work. The factors which play a vital role in

the selection of roosts is the risk of predation and

physical environment (Vanhof and Barclay, 1996). The

maternal colony is maintained during the non breeding

season which shows high roost fidelity and sensitivity to

non tactile disturbances.

The study colony of H.ater is located in the heart

of Tirunelveli town, urban ecosystem. Urban

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Journal of Research in Ecology (2015) 2(3): 018 – 025 020

Table -1 Survey on Roosts of Hipposideros ater in and around Tirunelveli (2001 - 2012)

Sl.

No Place Nature Roosting Site Location / Environment

Light

pattern Threat

1 Palayamkottai

(Perumalpuram)

Residential centre - unused

kitchen of S.T. College Middle of human habitation Semi dark Human Disturbance

2 Tirunelveli Junction

Interior chamber of

Godown - Lakshmi

Tinkering workshop

Urban habitation (city limit) Dark Renovation

3 Tirunelveli Junction Theater unused Toilet Urban (city limit) Semi dark Human Disturbance

4 Palayamkottai Unused dungeon room of a

house Urban (city limit) Dark Fumigation

5 Therkukallur Mandapam - an old stone

building Agricultural (Village limit) Semi dark Human disturbance

6 Morapanadu Interior chamber Village with Agricultural

surroundings Semi dark Renovation

7 Kurukuthurai Community hall, small, dark Human habitat (city limit) Dark Human disturbance

8 Sivasilam Stone building of a Temple Entrance of village with

water supply Dark Not noticed

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021 Journal of Research in Ecology (2015) 2(3): 018 – 025

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Journal of Research in Ecology (2015) 2(3): 018 - 025 022

interferences like construction and renovation work

supplemented by weather imbalance lead to a drop in the

population of these smaller hipposiderid bats. The

continuous and periodic visits of the observers to the

roosting site may also be one of the major reasons to

create stress to these sensitive populations of H.ater. The

present study establishes gestation period of H.ater

colony as experiencing severe disturbances. The H.ater

bats are very sensitive and they cannot tolerate human

intruders (Vanitharani, 1998) during gestation period. In

addition to this smoke, oil and noise from automobile

workshops near the urban roosts make a decline in bat

population.

The colony of H.ater faces the problem of

intruders like H. speoris during lactation periods

periodically and M.lyra into roost during a particular

occasion. All these three types of bats prefer same

foraging area and roost in nearby areas. This causes the

competence for many factors including prey items which

can also be cited as one of the factors for the decline of

the population of H.ater. The predatory role on smaller

bats by the carnivorous M.lyra is also a point to be noted

for their decline in H.ater colony. The particular study

colony of H.ater is located in the urban ecosystem where

the colony members have to cover a large foraging area.

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023 Journal of Research in Ecology (2015) 2(3): 018 – 025

TABLE 2 : Composition of H.ater colony during the study period (Tirunelveli Junction - Tinkering Work Shop)

Year Month Male Female

J V SA A Total J V SA P.M. L.M. A Total Population Density Sex ratio M / F Introders

2001

July - 1 3 1 5 - - - - - 1 1 2 5:1

August - - - - 0 - - 2 - - - 2 13 0:2

November - 1 1 2 4 - 2 2 - Weaned 1 4 9 7 4:1

December - - 1 - 1 - - 2 - 4 - 6 3 1:6

2002

January - - 1 - 1 - - - - 2 - 2 4 1:2

February - - - - 0 - - - 4 - - 4 5 0:4

March - - - - 0 - - 1 2 - 2 5 5 0:5

April - - 1 - 1 - - 2 - 2 with pup - 4 19 1:4 H.Speoris

May 2 2 - - 4 4 2 2 - With pup

Weaned 3 4 15 12 4:15 H.Speoris

June 2 2 1 - 1 - 1 2 - Weaned 2 2 7 4 5:7

September 1 - - - 1 - - - - Weaned 1 2 3 4 1:3

October - - - - 0 - - 1 2 - - 3 3 0:3

November - - - - 0 - - - 2 3 with pup - 5 5 0:5 H.Speoris

December 1 - 1 1 3 - - - - 1 - 1 4 3:1

2003

January 1 - - - 1 - - - - - - 3 4 1:3

April 1 2 - - 3 1 - - 2 1 with pup 1 8 11 3:8

June - - - - 0 - - 1 - - - 18 11 0:1

September - 1 - - 1 - - 1 1 - - 1 2 1:1

October - - - - 0 - - 1 1 - - 2 2 0:2 M.Lyra

2004 April - 1 - - 1 - - - - 1 with pup - 2 3 1:2

July - - 2 1 3 - - - - - - 0 3 3:0

2005

January

Not tagged

2

May 2

November 2

J:Juvanile ; V: Volant ; S.A. : Sub Adult ; A: Adult ; P.M.: Pregnant Mother ; L.M: Lactating Mother

Fig 1. Shows the bat population of H. ater (dark line

indicates total & grey line mean population) in the

study area during the study period from 2001 to 2012.

Eventually pregnant and lactating females face the

burden of more energy expense. Lack or little foraging

experience of pups of urban roosting site might have led

to increased pup mortality. There is also a possibility of

pup fatality due to the heavy usage of pesticides to

control mosquitoes, rodents and insect pests in the

surrounding urban and agro-ecosystem which is their

foraging area. The sexual segregation of males during the

non-breeding season and the maintenance of nursery

colony by the female adults and sub adult males cause

severe stress to the members of the colony.

CONCLUSION

The present study has stressed the need for the

protection of roosting site of H. ater from the human

unintentional and intentional interferences. Protection to

the key roosts is the only possible way to save the

population of H.ater. At least, the maternity colonies can

be protected with legislation. Legislations in India should

come out of the farcical economic principles and the

tyrannical political interventions to be formulated by

giving sufficient attention to genuine scientific

information from active field biologists (Vanitharani,

2004 a and b). There is a need for the formulation of

legislations to protect the key roosting sites which in turn

can bring a large ecological value to the nation. Bat

conservation societies can encourage and recommend the

farmers to build bat houses in their fields (Mac Cracken

and Long,1999). Production of bats' sex attractant

analogue and their deciphering will definitely pave a way

for species specific conservation in their roost and bat

houses. Above all creating awareness about the role of

bats' in the ecosystem is more important.

REFERENCES

Cloudely - Thompson JL. 1980. Woodlice as a material

for research projects. J. Biol Edu., 2: 107-118.

Fujita NS and Tuttle DM. 1991. Flying foxes;

(Chiroptera;Pteropodidate). Threatened animal of key

ecological and economic importance. Con. biol., 5: 455-

463.

Gopalakrishnan A and Madhavan A. 1978. Breeding

habits associated phenomena in some Indian bats. J.

Bom. Nat. His. Soc.,3:511-517.

IUCN. 2003. Guidelines for Application of IUCN Red

List Criteria at Regional Levels: Version 3.0. IUCN

Species Survival Commission. IUCN, Gland,

Switzerland and Cambridge, UK. ii + 26 pp.

Jeyaprabha L and Vanitharani J. 2003. Roosting

ecology and conservation status of bats in Tirunelveli

district. In : Annamalai,R., Narayanan, M., and

Vanitharani, J. (Eds.). Proceedings of 28th Conference

Ethol. Soci. India. Pp. 63-65.

Kunz TH. 1982. Roosting ecology. In: Ecology of bats

(Eds.). Kunz,T.H. Plenum Press, New York.

Washington. 35-57.

Lewis SE. 1995. Roost switching in bats- A review.

J.Mammal., 76:481-496.

Mac Cracken GF and Long LF. 1999. Nature’s Crop

Dusters-Eperts from Abstract Presentation, First Agrobat

Workshop in Bat Conservation International

Newsletter.www. batcon. org. news 2/scripts

Vanhof MJ and Barclay RMR. 1996. Roost site

selection and roosting ecology of forest dwelling bats in

Southern British Columbia. Can. J. Zool.,83:1799-1805.

Vanitharani J. 1998. Studies on the changes of wing

morphology and body weight in few species of South

Indian Bats. Ph.D., Dissertation submitted to Madurai

Kamaraj University, Madurai, Tamil Nadu. S. India.

Vanitharani J. 2004 a. Conservation strategies and

action plan for bats of Tamil Nadu. In: Tamil Nadu

Biodiversity strategy and action plan – Chordate

Sophia, 2015

Journal of Research in Ecology (2015) 2(3): 018 - 025 024

diversity (Eds.). Annamalai. R. Tamil Nadu forest Dept.

Govt. of Tamil Nadu, Chennai. Pp.14-127.

Vanitharani J. 2004 b. The emerging trends in the bio-

diversity of bats in Tamil Nadu. Mapana J. of Sci., 14-

27.

Sophia, 2015

025 Journal of Research in Ecology (2015) 2(3): 018 - 025

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