Journal of Threatened Taxa | www.threatenedtaxa.org | 26 October 2021 | 13(12): 19675–19688

 

ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) 

https://doi.org/10.11609/jott.7468.13.12.19675-19688

#7468 | Received 24 May 2021 | Final received 13 August 2021 | Finally accepted 12 September 2021

 

 

Roosting habits and habitats of the Indian Flying Fox Pteropus medius Temminck, 1825 in the northern districts of Tamil Nadu, India

 

M. Pandian 1 & S. Suresh 2

 

1 No. F1901, Taisha, Natesan Nagar West, Virugambakkam, Chennai, Tamil Nadu 600092, India.

2 Department of Statistics, University of Madras, Chepauk, Chennai, Tamil Nadu 600005, India.

1 pandian.m14@gmail.com (corresponding author), 2 sureshstat22@gmail.com

 

 

 

Editor: C. Srinivasulu, Osmania University, Hyderabad, India.     Date of publication: 26 October 2021 (online & print)

 

Citation: Pandian, M. & S. Suresh (2021). Roosting habits and habitats of the Indian Flying Fox Pteropus medius Temminck, 1825 in the northern districts of Tamil Nadu, India. Journal of Threatened Taxa 13(12): 19675–19688. https://doi.org/10.11609/jott.7468.13.12.19675-19688

 

Copyright: © Pandian & Suresh 2021. Creative Commons Attribution 4.0 International License.  JoTT allows unrestricted use, reproduction, and distribution of this article in any medium by providing adequate credit to the author(s) and the source of publication.

 

Funding: None.

 

Competing interests: The authors declare no competing interests.

 

Author details: M. Pandian has completed MSc, PhD, in Botany and BLIS from University of Madras and Bachelor of Education (BEd) from Annamalai University, Chidambaram and now serves in Tamil Nadu Police Department. His area of interest is ecology and nesting biology of birds and has published a few papers on house sparrows, weaver birds, munias and ring-necked parakeets.  S. Suresh has completed MSc, and PhD, in Manonmaniam Sundaranar University, Tirunelveli and a recipient of INSPIRE Fellow under Department of Science and Technology. He has published few articles in the field of time series analysis and data mining in reputed journals. He is a life member of statistics forums IISA and ISPS. He has rich knowledge in R programming languages.

 

Author contributions: MP has conceptualized, designed the research, performed survey, wrote paper, reviewed and edited the paper for final approval. SS has analysed the data and gave interpretations.

 

Acknowledgements: We thank D. Balaji (Villupuram district), Minnal A. Giridharan, Chitteri S. Prabakaran, Teacher (Ranipet district) and Minnal T. Selvapandian (Mumbai) for assisting in the survey by data collection, data analysis and taking photographs/ videography of bats in the field.

 

 

 

Abstract: This paper pertains to the study on roosting habits and habitats of the Indian Flying Fox Pteropus medius Temminck, 1825 in 12 villages of four northern districts—Vellore, Krishnagiri, Tiruvannamalai, and Viluppuram—of Tamil Nadu. Studies targeted roosting tree species, population status, diurnal-roosting behaviour, interactions with other animals, and probable threats to the species. A total of 22,365 individuals of the species were observed in 72 roosting colonies in 72 trees belonging to nine families, 11 genera, and 13 species. The tree species that harbored the greatest population of P. medius (n= 12,465) were those of Tamarindus indica L. (Fabaceae) (n= 39), followed by Ficus religiosa L. (Moraceae) (n= 3,960), Madhuca latifolia J.F. Macbr. (Sapotaceae) (n= 2,760), and Ficus benghalensis L. (Moraceae) (n= 1,620). One-Way ANOVA revealed that a significant relationship exists between  colony size and tree diameter at breast height (dbh), and their canopy size (p <0.05). However, no significant difference occurred between the colony size and tree height. The time taken for emergence of individuals of the colony from the canopy for foraging varied between 20 and 40 min after 1750 h in the evening. The species mostly roosted on trees proximal to human settlements, electrical power lines, and water bodies. Individuals of P. medius used various tree species in different areas in different geographical regions and did not maintain any consistency in roosting tree species selection. A majority of individuals (88.7 %; n= 887) were found roosting using both legs and a minority of P. medius (11.3 %; n= 113) were clinging to tree branches using one. Individuals of P. medius flew to nearby water bodies to quench thirst and cool their bodies. Mating was observed during day roost in 146 pairs including male-female fellatio in seven pairs. Smoke from shrines in sacred groves, pruning of branches for various cultural reasons, populations of House Crow Corvus splendens (Vieillot, 1817) (Corvidae), Black-winged Kite Elanus caeruleus (Desfontaines, 1789) and Black Kite Milvus migrans (Boddaert, 1783) (both Accipitridae) were key disturbances to roosting populations of P. medius.

 

Keywords: Diurnal behaviours fellatio, mating, Pteropus giganteus, roosting trees, threats.

 

 

 

INTRODUCTION

 

The order Chiroptera consists of over 1,400 species of bats worldwide, of which 148 species occur in southern Asia (Simmons & Cirranello 2020; Srinivasulu et al. 2021a). Pteropodidae, the Old-World fruit-eating bats, are well adapted to live in the tropics, particularly in India, Bangladesh, Bhutan, Nepal, China, the Maldives, Myanmar, Pakistan, and Sri Lanka (Helgen et al. 2009; Jnawali et al. 2011). India harbors 12 species of fruit bats and among them three occur commonly; they include Pteropus medius, P. leschenaultii, and Cynopterus sphinx (Srinivasulu et al. 2021b). The Indian Flying Fox Pteropus medius Temminck, 1825 (earlier treated as P. giganteus) is one of the largest bats and is widely distributed in southern and south eastern Asia (Marimuthu 1996). This species is a gregarious, colonial mammal that roosts in large trees that possibly protect them from strong winds and offer an easy updrift access for flight. The number of individuals of P. medius per colony was found to be varied. Between 260 and 1,550 individuals were recorded during different months (January–October) in a single colony in the Kathmandu valley, Nepal (Manandhar et al. 2018), whereas a colony of 2,844 individuals was recorded in the Lower Dir district, Pakistan (Khan et al. 2021). A total of 11,000 individuals were counted on 182 trees in Jambughoda Wildlife Sanctuary, Gujarat (Vyas & Upadhyay 2014). An average of 43 to 6,141 individuals was counted in the colonies on 19 tree species in Odisha (Rao & Poyyamoli 2017). In Tamil Nadu, over 600 individuals in Nallur near Chennai (Smith 1998), 16,000 individuals in Srivaikundam (Sudhakaran et al. 2010), and 431 individuals in Pudukottai district were enumerated. They usually prefer to roost on tall trees in urban areas of Lahore, Pakistan (Gulraiz 2014).  In Tamil Nadu, they preferred Terminalia arjuna trees in Srivaikundam (Sudhakaran et al. 2010) whereas Vachellia leucophloea (= Acacia leucophloea) and Pongamia pinnata in Pudukottai district (Tangavelou et al. 2013)

Generally, bat roosting sites are found adjacent to water bodies (Fenton & Barclay 1980; Kunz 1982; Thomas 1988). The colonies of P. medius mostly preferred to choose trees for roosting near human settlements in India and Nepal (Bates & Harrison 1997; Katuwal et al. 2019). They exhibit various diurnal behaviour during day roost and belly-soaking behaviour is very common among this species during summer in Purulia district of West Bengal probably to regulate body temperatures (Dey et al. 2015). This species utilizes rain water droplets to quench its thirst by licking rain droplets from its patagium (Baskaran et al. 2016). The majority of individuals cling to the branches using either both legs or with single leg (Rao & Poyyamozhi 2017). Mating in the day roost and fellatio behaviour in hetero-sexual pairs was common among bats (Wilkinson 1986; Kerth et al. 2003; Tan et al. 2009), and so in P. medius individuals (Maruthupandian & Marimuthu 2013). The emergence time of P. medius individuals from the roosting trees varied: early emergence occurred during winter (1720‒1837 h) and delayed emergence during summer (1838‒1946 h) in Mohanlal Ganj, Uttar Pradesh (Ramkumar et al. 2019).

Populations of flying foxes are declining worldwide (Mildenstein et al. 2005; Stier & Mildenstein 2005) due to growing human population, destruction of habitats by felling of trees (Chakravarthy & Yeshwanth 2008), hunting by humans (Marimuthu 1996), shortage of their food resources, and urbanization (Fujita & Tuttle 1991; Mickleburgh et al. 2002). Deforestation, electrocution, expansion of highways, construction of buildings, and hunting reduces populations of P. medius (Molur et al. 2008; Ali 2010). A variety of birds of prey and various reptiles including snakes and lizards prey upon bats (Pierson & Rainey 1992). Ethnic communities usually hunt the Indian Flying Fox for meat as they believe it to have medicinal value (Acharya 2008; Thapa 2008). Various conservation attempts have been made for tree roosting P. medius (Katuwal et al. 2019). The IUCN Red List of Threatened Species categorises conservation status of this species as ‘Least Concern’ (Tsang 2020). No detailed studies were carried out on the habits and habitats of P. medius in the northern parts of Tamil Nadu. Hence to fill up this gap the present study was carried out.

This study, focussing on how habitat disturbances will affect the populations of P. medius, will contribute to future studies on the role of habitat disturbances on species in southern India. In this study, we aimed to document the diurnal roosting behaviour of P. medius with special reference to trees utilized in northern Tamil Nadu. The following objectives were targeted: (1) to assess the population status of P. medius and roosting tree species in the study area; (2) to understand the relationship between the roosting sites of P. medius and distances from human settlements, electric power lines, water bodies, and mobile-phone towers; (3) to document diurnal behaviours including mating and pre-emergence patterns; (4) to know interaction with other animals; and (5) to access the probable threats to their populations.

 

 

MATERIALS AND METHODS

 

Study Area

The study was carried out in 12 villages (listed in the legend of Figure 1) located in Krishnagiri, Vellore, Tiruvannamalai, and Viluppuram districts of northern Tamil Nadu (c. 17,000 km2, c. 80,40,000 human population). Agriculture is the principal occupation of the residents. The maximum and minimum annual temperatures in these districts are 36 oC and 20 oC, respectively. The average annual rainfall is 1,060 mm (www.tn.gov.in).

 

 

Methods

We selected 72 active roosting colonies of P. medius distributed on 72 trees belonging to 13 species in 12 villages where P. medius populations were known to be locally present through nomadic gypsies. The number of P. medius observed on each tree was considered a single roost/colony. The roosting colonies and trees were surveyed between 0600 and 1900 h from June 2020 to January 2021.

 Questionnaire study: Eighty respondents, all above 60 years old, residing adjacent to the roosting sites were interviewed as they have information from the past, in the selected 12 villages using a questionnaire survey form (in the Tamil language). The questionnaire form included questions on time periods of existence of the local P. medius colonies, population trends, details on roosting trees and tree selection, persecution and hunting of the flying fox, and perception of the local community about the animal as a nuisance, and the probable threats to the populations of local P. medius colonies.

Population count: A population count of the selected P. medius colonies was carried out visually and by using a pair of Super Zenith field binoculars (Model No. 20 x 50 Field 3O, Jack Berg, El Paso, Texas, USA) following Barlow’s (1999) direct roost-count method. The count was conducted fortnightly during June‒July 2020 and the numbers were arithmetically averaged.

Behavioural study: Some behaviours of the species in the colonies such as grooming, mating, and interactions with other animals were also observed. Anthropogenic impacts such as smoke from cooking, hunting, and pruning of trees chosen for roosting were observed and the level of impact was categorized. The height was measured using Silva Clinometer (Gulraiz 2014), dbh (diameter at breast height), canopy width and distance between roosting trees were measured using 100 m measuring tape. The nearest human settlements, power lines, water bodies, and mobile-phone towers were measured using a 100 m measuring tape. The canopy width was obtained by cross method (Blozan 2006) by measuring the edge of the canopy shadow on the ground. The pre-emergence and emergence activities were observed between 1700 and 1900 h for 20 days in January 2021. Locations of the colonies and mobile-phone towers were determined using a standard GPS (Garmin Etrex 20x, 2017, Garmin Corporation, Taiwan). Photographs and videography were made using a digital camera (Nikon Coolpix P1000 Super-telephoto, Nikon).

 

Data Analysis

One-way analysis of variance (ANOVA) was used to test the difference in means between the numbers of P. medius counted and the types of roosting tree species by using Statistical Package for Social Science (SPSS version 25.0 software). Roosting tree species having more than two individuals were considered for analysis. Those tree species with less than two individuals were ignored. One-way ANOVA was used to test the significance between the numbers of individuals of P. medius counted and the height, dbh, and canopy size of roosting trees. Test of significance between the variables was assessed at p <0.05.

 

RESULTS

 

Tree species selection for roosting

A total of 22,365 individuals of P. medius were counted from 72 colonies (Table 1). The roosting sites occurred in and around 11 human settlements, 11 sites in farmlands, and five sites near shrines within sacred groves. Out of the 12 villages, the maximum individuals that is 32.64 % (n= 7,298) occurred in Ongapadi (Vellore district) and the least 1.77 % (n= 398) in Junjupalli (Krishnagiri district). Among four districts, the highest population of P. medius (n= 9,268; 41.45 %) occurred at Vellore district on 10 trees, followed by 23.68 % (n= 5,298) on 47 trees in Tiruvannamalai district, and 20.91 % (n= 4,678) on seven trees in Krishnagiri district. The least populations of 13.95 % (n= 3,121) were counted on eight trees in Viluppuram district. On an average, 310 individuals of P. medius /tree existed in the study area. (Table 1, Image 1).

Altogether, 13 species belonging to 11 genera and nine families of 72 trees were roosted upon by P. medius. Bambusa arundinacea (L.) Voss (Poaceae), a large, arborescent herb, was one among the 13 species. A total of 12,465 individuals (55.73 %) of P. medius lived on 49 trees of the family Fabaceae. Most of the colonies (53.9 % of their total population, n= 12,055) were on Tamarindus indica L. (n= 39) and a minimum population (0.12%, n= 28) on a single Lannea coromandelica (Houtt.) Merr. (Table 2).

The tree species used for roosting, such as Delonix regia (Boj. ex Hook.) Raf., Azadirachta indicaA. Juss., Ceiba speciosa (A.St.Hil.) Ravenna, Lannea coromandelica (Houtt.) Merr., Madhuca longifolia J.F.Macbr., Syzygium cumini (L.) Skeels., and Terminalia arjuna L. were represented only by either one or two trees which were excluded from the analysis. Statistical testing (ANOVA) revealed a significant relationship between the means of P. medius individuals and the tree species chosen by P. medius for roosting (F5,56= 5.35, p <0.05).

One-way ANOVA shows the relationship between the height, dbh, and canopy size of the roosting trees. However, no significant relationship occurred between the average number of P. medius and heights of the trees (F2,69= 1.42, p >0.05). Nevertheless, there was a significant difference between the average number of P. medius and the dbh of trees used by P. medius for roosting (F2,69= 8.25, p <0.05). In addition, significant differences occurred between the number of P. medius and the canopy size of roosting trees (F2,69= 10.34, p <0.05).

 

Apparent preference of trees close to human settlements

Sixty per cent of the trees used for roosting (n= 43) and 80 % individuals of total population of P. medius (n= 17,880) occurred within 100 m radius from human settlements. No roosting trees were located between 100 and 250 m. Only 40 % trees used for roosting (n= 29) and 20 % individuals (n= 4,485) of P. medius were found beyond 250 m (Figure 2).

Forty-three per cent of trees used for roosting (n= 31) and 64.75 % of P. medius (n= 14,482) occurred within a 25-m radius from electric power lines. A maximum of 84.72 % of trees used for roosting and 92.1 % P. medius (n= 20,600) occurred within a 100-m radius from power lines. Only 15.28 % of trees used for roosting (n= 61) and 7.9 % of P. medius (n= 1,765) occurred beyond 100 m. No mortality of P. medius due to electrocution was noticed during the study period (Figure 3).

Ninety-six per cent of trees used for roosting (n= 69) and 80.86 % of P. medius (n= 18,085) occurred within 1,000-m radius from water bodies such as lakes, ponds, rivers, and canals (Figure 4). Thirty-two per-cent of trees used for roosting (n= 23) and 50.4 % P. medius individuals (n= 11,272) occurred within a 500-m radius from mobile-phone towers and 62.5 % trees (n= 45) and 28.62 % P. medius (n= 6,403) were observed within a 501‒2000 m radius from mobile-phone towers. The remaining 5.55 % trees (n= 4) and 20.97 % P. medius (n= 4,690) occurred beyond 2001 m from mobile-phone towers (Figure 5).

 

Perception of local people

Of the 80 local respondents interviewed, 87 % residents (n= 66) were concerned over the declining populations of P. medius and the numbers of trees used for roosting. That the residents of these villages consider roosting populations of flying foxes important in their culture and life is notable. For example, if they considered it a bad omen, they would have either cut those trees that accommodate roosting populations of P. medius or chased the roosting colonies away from the trees. However, in Junjupalli village, we observed that soon after a marriage ceremony, the married couple worshipped the tree (Ficus benghalesnsis) supporting a roosting population of P. medius. Residents from the villages reported that the numbers of P. medius had reduced, compared to six decades ago. Thirty-five residents (44 %) indicated either occasional or clandestine hunting of P. medius for folk-medicinal reasons. Seventy-four residents (92 %) considered the presence of a roosting colony as a sign of prosperity to their village. Sixty residents (75 %) indicated that cracker bursting was always done only after sunset when P. medius population was away from the trees for foraging. To protect roosting colonies of P. medius residents of Ongapadi village avoided bursting crackers during festive times. Seventy-four residents (92 %) considered P. medius populations within the village were never a nuisance; despite the fact that these animals desecrate houses, walls, and other common public areas under the roosting trees, and the foul odour emanating from the droppings. Sacredness and an environmental value addition because of culture, offer ‘protection’ to populations of P. medius contributing to their conservation.

 

Behaviour of P. medius

During the north-east monsoon rains (October—November 2020), individuals of P. medius were observed clinging to tree branches with their heads and ventral parts of their body wrapped with their membranous wings. Immediately after the rain, they flap their wings speedily and move from one branch to another. After the rain, they groom, scratch, and lick water droplets from their body (Image 2).

During hot summer days (June—July), individuals of P. medius moved from the top of the canopy downwards, i.e., midparts of the tree and roosted on large tree trunks, probably to avoid direct exposure to sunlight. In June‒July 2020 in Marudhadu village, five incidents of P. medius individuals flying to a nearby lake and soaking the ventral part of their body were observed.

 

Mating

One-hundred-and-forty-six incidents of mating were observed in the studied villages between 0700 h and 1645 h during October—December 2020. A maximum of 26 pairs engaged in courtship and copulation was observed in Kesavapuram village, and two mating pairs in Anumandhai village. Before copulation, seven incidents of males licking the genitalia of the females were observed, which occurred for 2—4.5 min. After copulation, both pairs moved away from each other and female‒male fellatio stopped. Two instances of males licking their own penises before copulation were observed in Padhiri village (Table 3; Image 3).

 

Emergence from trees

A total of 20 pre-emergence and emergence activities were observed for 20 days continuously from 1700 to 1900 h in Kazhuperumbakkam and Maruvur (Viluppuram district). Frequent and irregular migrations of individuals from one branch to another either in the same tree or between different trees occurred between 1710 and 1750 h. From a minimum of one to a maximum of 11 were found flying, encircling the canopy for a few minutes and returning to the tree used for roosting. Wing flapping and grooming activities were high and almost all individuals of P. medius concurrently made vocal communications, resulting in a loud, collective noise around the roost. The emergence of the first batch of individuals (10‒50) from the colony occurred between 1750 and 1810 h. The emergence time of the last batch of the colony was between 1820 and 1840 h. The time taken for emergence of individuals (80‒100) of the colony from the canopy varied between 20 and 40 min.

 

Interactions with other animals

Twelve incidents of Macaca radiata (E. Geoffroy, 1812) (Cercopithecidae) living on T. indica trees in Gudiyatham and Rayandapuramwere observed. When a troop of M. radiata climbed over T. indica trees to feed on flowers and raw fruits, P. medius individuals from the nearby branches flew away from these trees to nearby trees. In one instance, one M. radiata was found slapping a roosting P. medius when the latter hindered it while plucking fruits of T. indica. Corvus splendens frequently visited the trees used by P. medius for roosting, disturbing them. When the P. medius started to fly, C. splendens selectively chased the juveniles of P. medius away. A total of 36 incidents of C. splendens chasing P. medius individuals from roosting colonies were observed. But no incidents of C. splendens predating on the juveniles of P. medius were found during the study (Fig 10).

 

Threats

Smoke disturbance to roosting colonies of P. medius was common around shrines located within sacred groves. Local residents cook porridge on firewood stoves to offer to deities in the sacred groves in Marudhadu, Kazhuperumpakkam, Padhiri, Maruvur, and Chenur during July‒August and January‒February. The emerging smoke disturbed P. medius individuals, driving them away from the trees to migrate to other trees (e.g., T. indica and F. religiosa) situated outside the villages for roosting. 

Trees chosen for roosting by P. medius adjacent to residential areas and farm lands are frequently pruned because the village administrators see them as obstructions to electric power lines and villagers who see them preventing sunlight to crop plants. One P. medius individual was noticed with a damage on its patagium. Although the exact cause for the damage was unknown. One Black-winged Kite Elanus caeruleus (Desfontaines, 1789) was seen hovering and roosting on power lines in the vicinity of trees used by P. medius for day roost at Maruvur village, although no incident of attack by E. caeruleus on P. medius was observed. Villagers remarked that Black Kites, Black-winged Kites, and House Crows occasionally predate on the juveniles of P. medius.

 

 

DISCUSSION

 

Tree species selection for roosting

The Indian Flying Fox has been known to use nine tree species in avenues in Delhi (Mishra 2010) and 18 tree species in Uttar Pradesh (Kumar et al. 2017). In the present study conducted in Vellore, Krishnagiri, Tiruvannamalai, and Viluppuram districts in northern Tamil Nadu, P. medius populations used 13 tree species belonging to nine families and 11 genera for roosting. Among the 13 species of roosting trees, T. indica and L. coromandelica are the most preferred by the flying fox in Tamil Nadu. The same taxa also commonly occur in Vellore, Krishnagiri, Tiruvannamalai, and Viluppuram districts, except H. brasiliensis (Vijayasankar et al. 2012) but these tree species were not selected by P. medius populations for roosting. Tree species such as P. longifolia, Neolamarckia cadamba (Roxb.) Bosser. (Rubiaceae), Eucalyptus citriodora (Hook.) K.D.Hill & L.A.S. Johnson (Myrtaceae), Mimusops elengi L. (Sapotaceae), Samaneae saman (Jacq.) Merr. (Fabaceae), Tectona grandis L.f. (Lamiaceae), Peltophorum pterocarpum (DC.) K.Heyne, and Lagerstroemia speciosa (L.) Pers. (Lythraceae) (Rao & Poyyamoli 2017) were not used by P. medius in Vellore, Krishnagiri, Tiruvannamalai, and Viluppuram disricts. In Pudukkottai district, central Tamil Nadu, P. pinnata and V. leucophloea, especially in the sacred groves, were the trees used maximally for roosting (Tangavelou et al. 2013). In the present study, P. pinnata was the tree that housed maximum roosting populations of P. medius (n= 71). Different species of Eucalyptus (Myratceae) were the most used trees for roosting in Kathmandu (Nepal) (Manandhar et al. 2018). But in the present study area no Eucalyptus tree species was used by P. medius for roosting, although various species of Eucalyptus occur abundantly in the studied districts. The reason may be due to the felling of Eucalyptus trees periodically by the social forestry department because these trees were not allowed grow for long periods and hence, P. medius might have avoided selecting this tree species. These findings indicate that P. medius use various tree species in different geographical regions and do not maintain any consistency in tree selection for roosting.

No positive relationship occurred between the numbers of P. medius and heights of the trees used for roosting (F2,69= 1.42, p >0.05). Significant relationship existed between the dbh and canopy size of trees selected for roosting and the number of P. medius individuals in urban and semi-urban areas in Uttar Pradesh (Kumar & Elangovan 2019). In the present study, a significant, positive relationship occurred between the means of P. medius individuals and numbers of A. lebbeck, P. pinnata, T. indica, B. arundinacea, F. benghalensis, and F. religiosa chosen by P. medius for roosting (F5,56= 5.35, p <0.05). There was a significant difference between the average number of P. medius and the dbh (F2,69= 8.25, p <0.05) and the canopy size of trees used by P. medius for roosting (F2,69= 10.34, p <0.05). It indicates that individuals of P. medius preferred trees with larger dbh and larger canopy size for roosting in the study area.

 

Apparent preference of trees close to human dwellings

In the Indian subcontinent, populations of P. medius mostly preferred to choose trees for roosting near human settlements (Bates & Harrison 1997). In lower Nepal, most of the colonies of P. medius were recorded close to human settlements and in farmlands (Katuwal et al. 2019). This species roosts on trees that occur close to human settlements in Tirunelveli district, viz., sacred groves, and agricultural lands (Jayapraba 2016). In the present study, 60 % of trees (n= 43) chosen for roosting and 80 % P. medius individuals (n= 17,880) were found within 100 m radius from human settlements and hence it is in accordance with the observations of Bates & Harrison (1997), and Katuwal et al. (2019).

 

Behaviours observed

In New South Wales, Australia, flying foxes were observed to visit nearby water bodies in peak summers to soak their fur and wings to cool their bodies (Welbergen et al. 2008). Belly-soaking behaviour is very common among the Indian Flying Fox during summer in Purulia district of West Bengal (Dey et al. 2015). In the present study, the observations of partial dipping of its ventral body surfaces in water might have been to quench its thirst and to reduce its body temperatures during hot summer and hence it matches with the views of Dey et al. (2015) and Welbergen et al. (2008).

Populations of P. medius usually roost on trees for 12‒14 h daily hanging from branches. A majority of individuals (88.7 %) were found roosting using both legs and a minority of P. medius (11.3 %) were clinging to tree branches using one. They probably relax their leg muscles by alternately using both or a single leg and it requires further studies. The majority of individuals clinging to the branches used both legs during day roost as stated by Rao & Poyyamozhi (2017).

After rainfall the individuals of P. medius, groom, scratch, and lick their body to remove the water droplets (Maruthapandian & Marimuthu 2013). This species utilizes rain water droplets to quench their thirst by licking rain droplets from the wing membrane (Baskaran et al. 2016). As stated by the above authors, in the present study also we observed similar behaviours of P. medius individuals scratching and licking its body and removing water droplets. The droppings of P. medius desecrate human residences, common usage areas, and cause foul odour, but the residents tolerate it and allow roosting colonies on trees in their villages.

The occurrence of mating in the day roost and fellatio behaviour in hetero-sexual pairs was common among P. medius individuals (Wilkinson 1986; Kerth et al. 2003; Maruthupandian & Marimuthu 2013; Tan et al. 2009). Similar behaviours while mating during day and female-male fellatio were observed in the current study as stated by the above authors.

 

Emergence from trees

The emergence time of P. medius individuals from the trees varied: early emergence occurred during winter (1720‒1837 h) and delayed emergence during summer (1838‒1946 h) in Mohanlal Ganj, Uttar Pradesh (Ramkumar et al. 2019). In the present study the emergence period during the winter season was between 1750‒1840 h and it nearly corroborates with the observations of Ramkumar et al. (2019). The time taken for emergence of all the individuals of the colony was found to vary: 21 min to 39 min. The variations of emergence time during summer have not been studied.

 

Interactions with other animals

A variety of birds of prey, both Falconiformes and Strigiformes, various reptiles including snakes and lizards prey upon them (Pierson & Rainey 1992). Though monkeys and house crows caused disturbance to P. medius individuals, no incidents of predation was reported in the present study area. Villagers remarked that individuals of Black Kites and Black-winged Kites had frequented roosting colonies and predate of juveniles of P. medius and hence it corroborates with the findings of and Pierson & Rainey (1992). However, no predation by Black Kites, Black-winged Kites, and reptiles were noticed in the study sites.

 

Threats

This species roost on trees that occur close to human settlements, farmlands and sacred groves. Because of human habitation, electrical power lines usually occur close to those roosting trees. Ali (2010) reported small numbers of P. medius were found electrocuted and died in Dhubri district, Assam. The present survey revealed that no mortality of P. medius individuals was found in the surveyed four districts. Although 84.72 % trees chosen for roosting and 92.1 % P. medius individuals (n= 20,600) occurred within a 100-m radius from electrical power lines, no mortality due to electrocution was observed.

Hunting of bats for meat is still prevalent in some parts of Nepal (Katuwal et al. 2019). The meat of flying foxes (‘valguli mamsa’ in local language) is believed to be of some therapeutic value and its consumption is recommended locally. Meat of this species is consumed for treating rheumatism in India (Nowak 1999) and the people of Attapadi region (Kerala) believe that the meat of P. medius treats asthma and chest pain (Padmanaban & Sujana 2008). During the survey, 44 % of residents (n= 35) indicated either occasional or clandestine hunting of P. medius for folk-medicinal reasons.

Electromagnetic radiations exert an abnormal behaviour and affect the foraging activities of bats in Aberdeen, Scotland. Their activity was more rigorous in the control sites than the sites exposed to a high level (>2v/m) of electromagnetic radiation (Nicholls & Racey 2007). In Mumbai, the number of flying foxes was found to have decreased when mobile-phone towers occurred within 80 m from a roosting colony (Kumar 2010). In the present study the minimum distance between a tree used for roosting and a mobile-phone tower was 40 m at Ongapadi (Vellore district) and the maximum 6,000 m  in Maruvur (Viluppuram district). The trees used for roosting and P. medius populations revealed that a large number of trees chosen for roosting (31.94 %; n= 23) and P. medius individuals (50.4 %; n= 11,272) occurred within 500 m radius from the mobile-phone towers. However, in the event of the existence of mobile-phone towers in almost all villages, the situation of a tree 40 m distance from the mobile-phone tower, the exact impact of the mobile-phone tower on the roosting colonies of P. medius needs further study.

 

 

CONCLUSION

 

The populations of P. medius used 13 tree species belonging to 11 genera and nine families for roosting at various habitats, such as human dwellings, farmlands, and water bodies. No positive relationship occurred between the numbers of P. medius and heights of the trees used for roosting. There was a significant difference between the average number of P. medius and the dbh and the canopy size of trees used by P. medius for roosting. The individuals of P. medius were found soaking themselves in water during summer probably to reduce body temperatures. While roosting, they mostly cling on to tree branches using both legs, rarely using one. Mating and fellatio behaviour in hetero-sexual pairs were observed during the day roost. The time taken for emergence of individuals of the colony from the canopy varied between 20 and 40 min. No mortality due to electrocution was observed. The impact of mobile-phone towers on roosting colony needs further study. The roosting populations were disturbed by individuals of Bonnet Macaque, House Crow, Black Kite, and Black-winged Kite. Anthropogenic impacts like hunting, pruning trees used for roosting and smokes emanated from sacred groves during festivals  pose a threat to the populations of P. medius.

In spite of rapid urbanization, industrialization, population increase, habitat destruction, hunting by villagers and decreasing areas of cultivation including orchards, considerable P. medius populations exist in the study area.  A special management plan could be devised for the area, considering the anthropogenic and natural stresses to which the habitat is currently subjected. The present roosting sites should be declared as protected areas and further organisations (NGOs) have to play a major role in creating awareness among the general public to protect this species. This study clearly demonstrates the presence of 22,365 Indian Flying Fox individuals in their natural habitats and identifies current and emerging challenges in conservation of habitats of such key species in the natural ecosystems.

 

Table 1. District-wise details of villages, GPS co-ordinates, number of roosting trees and total number of Pteropus medius counted in the study area.

 

      District

Name of the village

             GPS

Total no. of trees have roosting colony

Total no. of P. medius counted on these trees

Percentage

(%) of P. medius

1

Vellore

Gudiyatham

12.938438oN, 78.861062oE

4

1970

8.8

2

Ongapadi

12.822734oN, 78.946628oE

6

7298

32.63

3

Krishnagiri

Junjupalli

12.564656oN, 78.164119oE

4

398

1.64

4

Chenur

12.360311oN, 78.583989oE

3

4280

19.13

5

Tiruvannamalai

Rayandapuram

12.092188oN, 78.928710oE

13

2723

12.17

6

Kesavapuram

12.655683oN, 79.126282oE

18

1417

6.33

7

Vandavasi

12.510984oN, 79.597503oE

10

700

3.12

8

Marudhadu

12.490742oN, 79.653357oE

6

458

2.94

9

Viluppuram

Kazhuperumpakkam

12.067317oN, 79.829502oE

1

780

3.48

10

Anumandhai

12.131800oN, 79.911418oE

4

1251

5.59

11

Maruvur

12.164664oN, 79.515650oE

1

410

1.83

12

Padhiri

12.314802oN, 79.755639oE

2

680

3.04

Total

                      4

                 12

 

72

22365

100

 

 

Table 2. Details on the diversity of roosting trees and total Pteropus medius counted in the study area.

 

Type of roosting trees

Family

Total no. of trees have P. medius roosting

Total no. of P. medius individuals counted

1

Albizia lebbeck (L.) Benth.

Fabaceae

5

219

2

Dellonix regia (Boj. ex Hook.) Raf.

Fabaceae

1

120

3

Pongamia pinnata (L.) Panigrahi

Fabaceae

4

71

4

Tamarindus  indica L.

Fabaceae

39

12055

5

Azadirachta indica A.Juss.

Meliaceae

1

46

6

Bambusa arundinacea (L.) Voss

Poaceae

7

468

7

Ceiba speciosa (A.St.Hil.) Ravenna

Malvaceae

2

175

8

Ficus benghalensis L.

Moraceae

4

1620

9

Ficus religiosa L.

Moraceae

3

3960

10

Lannea coromandelica (Houtt.) Merr.

Anacardiaceae

1

28

11

Madhuca longifolia J.F.Macbr.

Sapotaceae

1

2760

12

Syzygium cumini (L.) Skeels.

Myrtaceae

2

56

13

Terminalia arjuna (Roxb.) Wight & Arn.

Combretaceae

2

787

Total

9

72

22365

 

 

Table 3. Details of mating pairs and female-male fellatio observed during day roost in October and December 2020 in the study area.

 

      District

Name of the village

Total no. of mating individuals observed

Female-male fellatio observed

1

Vellore

Gudiyatham

12

2

2

Ongapadi

08

0

3

Krishnagiri

Junjupalli

14

0

4

Chenur

04

1

5

Tiruvannamalai

Rayandapuram

22

0

6

Kesavapuram

26

2

7

Vandavasi

08

0

8

Marudhadu

14

0

9

Viluppuram

Kazhuperumpakkam

20

1

10

Anumandhai

02

0

11

Maruvur

06

0

12

Padhiri

12

1

Total

                      4

                 12

146

7

 

 

For figures & images - - click here

 

 

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