Journal of Threatened Taxa | www.threatenedtaxa.org | 26 September 2018 | 10(10): 12344–12349

 

 

 

A new record of the rare Hardwicke’s Woolly Bat Kerivoula hardwickii (Horsefield, 1824) (Mammalia: Chiroptera: Vespertilionidae) after 23 years from a lowland rainforest of Sri Lanka

 

Dinesh Gabadage 1, Gayan Edirisinghe 2, Madhava Botejue 3 , Kalika Perera 4, Thilina Surasinghe 5 & Suranjan Karunarathna 6

 

1,2,3,4 Biodiversity Conservation Society, No. 150/6, Stanly Thilakaratne Mawatha, Nugegoda 10250, Sri Lanka

5 Department of Biological Science, Bridgewater State University, Bridgewater, MA 02325, USA

6 Nature Explorations & Education Team, No. B-1 / G-6, De Soysapura Flats, Moratuwa 10400, Sri Lanka    

1 degabadage@gmail.com, 2 gayan.yza@gmail.com, 3 madhavabotejue@gmail.com, 4 kalikap23@hotmail.com, 5 tsurasinghe@bridgew.edu, 6suranjan.karu@gmail.com (corresponding author)

 

 

 

doi: https://doi.org/10.11609/jott.4100.10.10.12344-12349  |  ZooBank: urn:lsid:zoobank.org:pub:606830F4-08A7-4407-B8A9-A50BAC3E3F3E

 

Editor: Anonymity requested. Date of publication: 26 September 2018 (online & print)

 

Manuscript details: Ms # 4100 | Received 26 February 2018| Final received 12 September 2018 | Finally accepted 15 September 2018

 

Citation: Gabadage, D., G. Edirisinghe, M. Botejue, K. Perera, T. Surasinghe & S. Karunarathna (2018). A new record of the rare Hardwicke’s Woolly Bat Kerivoula hardwickii (Horsefield, 1824) (Mammalia: Chiroptera: Vespertilionidae) after 23 years from a lowland rainforest of Sri Lanka. Journal of Threatened Taxa 10(10): 12344–12349; https://doi.org/10.11609/jott.4100.10.10.12344-12349

 

Copyright: © Gabadage et al. 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: Biodiversity Secretariat, Sri Lanka.

 

Competing interests: The authors declare no competing interests.

 

Acknowledgements: We thank Kelum Manamendra-Arachchi, Sonali Premarathne, Survey Department, and villages who helped in diverse ways to enrich the field works. This study was partially supported by a small grant from the Biodiversity Secretariat Sri Lanka.

 

 

 

Abstract: Distribution of Kerivoula hardwickii, Hardwicke’s Woolly Bat, in Sri Lanka is restricted to the central highlands and to the northeastern region of the country, and so far, only recorded from four distinct locations.  In Sri Lanka, this species was last documented in the year 1994 and no subsequent surveys recorded this species in Sri Lanka, thus considered rare in Sri Lanka.  In contrast, within its South Asian biogeography, K. hardwickii is widely distributed, particularly in Southeast Asia.  In this study, a single male of K. hardwickii was observed in lowland rainforest ecoregion of Sri Lanka near Labugama-Kalatuwana Forest Reserve where the bat was roosting on a curled live banana frond.  The bat was roosting 1.8m above the ground.  This was the first instance K. hardwickii recorded in the lowland rainforests of Sri Lanka, which extends this species’ biogeography of Sri Lanka into the lowland wet zone.  Thus, distribution range of K. hardwickii in Sri Lanka could be broader than historically documented.  Intensive surveys, particularly in lowland rainforest regions, are required to validate the true distribution of this bat in Sri Lanka.

 

Keyword: Banana frond, canopy cover, distribution, Kerivoula, pitcher plants, threatened.

 

 

 

 

Sri Lanka, though a relatively small island (~65,610km2) located in the Indian ocean, provides habitats for a rich assemblage of mammalian fauna.  Of the 95 species of terrestrial mammals recorded in the island, bats are the second most diverse mammalian order with 32 species (13 yinpterochiropteran and 19 yangochiropteran species) closely behind rodents with 34 species (Phillips 1980; Leowinta & Luk 2016; Yapa 2017; Edirisinghe et al. 2018).  Among Sri Lankan bats, two microbat species of the genus Kerivoula represented are K. picta (Painted Bat) and K. hardwickii (Hardwicke’s Woolly Bat) (Phillips 1935; Yapa & Ratnasooriya 2012; Yapa & Ratnavira 2013).  Although the latter species has a wide distribution range covering both southern and northern South Asia, southern China, and throughout continental and insular Southeast Asia, distribution of K. hardwickii in Sri Lanka is restricted to the central highlands and northeastern part of the country (Bates & Harrison 1997, 2000; Francis 2008; Slade 2017).  This species is widespread in Southeast Asia, including Myanmar, Thailand, Laos, Vietnam, Cambodia, Peninsular and Bornean Malaysia, Indonesia, and the Philippines, but show a patchy and relatively isolated distribution in India, Pakistan, and China (Bates & Harrison 1997; Menon 2003; Francis 2008).  Distribution of K. hardwickii is not well studied in Sri Lanka and recent surveys failed to document this species in or outside its historical range (Rubsamen et al. 2004; Yapa et al. 2005; DWC 2007a,b, 2008a,b; Yapa & Ratnasooriya 2012; Kusuminda et al. 2013; Yapa 2017; Edirisinghe et al. 2018).  Given the marked deferential distribution status, there is a discrepancy in the conservation status of K. hardwickii in the IUCN Red List of Threatened Fauna and Flora of Sri Lanka (Critically Endangered: Ministry of Environment 2012) versus the Global Red List (Least Concern: Rosell-Ambal et al. 2008).  Given the frequent records of K. hardwickii elsewhere, the low encounter rate of this species in Sri Lanka could be an artifact of imperfect detection or inadequacy of countrywide surveys on bats.  Here, we report documentation of K. hardwickii in lowland rainforests of Sri Lanka.

 

Materials and Methods

We conducted field excursions for a period of six days (06-11 of August, 2017) in the vicinity of Labugama-Kalatuwana Forest Reserve (6.842–6.8860N & 80.220–80.2590E, altitude ranges 30–202 m) in southwestern Sri Lanka (lowland wet zone; average annual precipitation >2,000mm, elevation <300m).  The general area is a habitat mosaic where lowland evergreen rainforests of secondary origin is the most dominant vegetation type.  In addition, agricultural land-cover types such as rubber, coconut, and banana plantations, paddy fields, and home gardens are scattered around our study area.  Through random walks, we first documented suitable bat roosting sites and subsequently surveyed each potential roosting site during both day (08:00–14:00 hr) and night (17:00–21:30 hr) and captured any bats present in the roosting site using a hand net (net depth: 45cm, net diameter: 30cm, mesh size: 1.5x1.5 mm).  To confirm species identification, we used several standard guides and keys (Phillips 1980; Srinivasulu et al. 2010; Yapa & Ratnavira 2013).  For all captured bats, we documented both morphological characteristics and morphometric variables using a digital Vernier calliper (RD-10, China), photographed (Canon 60D DSLR camera with EF 100mm f/2.8L Macro IS USM Lens) specimens, and immediately released them back to the site of capture.  In addition, we recorded air temperature and relative humidity using a multi-digital hygrometer (TA-138, China), and wind speed using a digital anemometer (MS-6252-A, China).

 

Results

A single male of K. hardwickii (Image 1) was observed (17:19hr on 10 August 2017) roosting on a curled live banana frond of a mature banana tree Musa paradisiaca located in a secondary forest patch (~163ha in size).  This site (6.8660N–80.2410E, altitude ~174m) is located 3.6km northeast of Labugama-Kalatuwana Forest Reserve in Thoranagoda (3.5km northwest of from Eheliyagoda City), situated in Ratnapura District within Sabaragamuwa Province of Sri Lanka (Fig. 1).  The roosting site (1.8m height) had about 70% canopy cover. During the time of observations, the wind speed was 1.22–2.16 km/h (average 1.68 km/h), temperature 25.3–28.2 0C (average 26.70C), and humidity 57–83 % (average 69.5%).  From our first time of observation, the bat remained in its roost for 51 minutes and left the roost around 18:10hr, immediately after the sun set.  The morphological and morphometrics featured of this individual resembled general description of K. hardwickii (Table 1 and 2).  Other bat species we documented in this survey included Pteropus giganteus, Rousettus leschenaulti, Cynopterus sphinx, Hipposideros ater, Hipposideros speoris, Pipistrellus tenuis, and Rhinolophus rouxii.

 

Discussion

Previously-known occurrence of K. hardwickii in Sri Lanka was limited to four locations (Fig. 1)—Kumbalgamuwa (1931, 914m, near Walapane, Nuwara-Eliya District, Central Province, Natural History Museum of London, Cat No. BMNH.1931.11.7.1 (Phillips 1932)); Pundaluoya (1,062m, near Kikiliyamana, Nuwara-Eliya District, Central Province, Natural History Museum of London, Cat No. BMNH.3840346 (Bates & Harrison 1997)); and Pallama (1994, 500m, near Matale, Matale District, Central Province, Harrison Zoological Museum Cat No. HZM.3.31606 (Bates & Harrison 1997)); and Nilaweli (1945, 8m, near Kumpurupiddi, Trincomalee District, Eastern Province, Kansas University Biodiversity Institute, Cat No. KUM.135734, (Slade 2017)).

In Sri Lanka, this species is purported to occur in small numbers and inhabit warm, montane (500–1,100 m) well-sheltered forested valleys throughout the central highlands of Sri Lanka.  According to our knowledge, this is the first photographic evidence of K. hardwickii from Sri Lanka with detailed morphological and morphometrics descriptions, and this is the first documentation after 1994 (Bates & Harrison 1997).  Our sighting suggests a greater distribution range of K. hardwickii, which may extend beyond the central highlands and northeastern lowland dry zone, into the lowland wet zone of Sri Lanka.  Since our encounter is limited to a single bat we draw a cautionary note regarding updating its conservation status.  Further research with a combination of repeated visits and mist netting should be carried out in this region prior to updating the species extent of occurrence and area of occupancy.  Moreover, we are also uncertain of the reason for low encounter rate of K. hardwickii and can be attributed to a combination of this species’ illusive behavior, small-size, use of cryptic roosting sites, and lower population density stemming from lack of suitable habitats and low availability of critical resources.

Within its South Asian biogeography, this species is mostly found in forests and woodlands (Molur et al. 2002), but they are also found in forest edges, paddy fields, home gardens.  Our documentation agrees with previous records of this species outside Sri Lanka as the landscape context of our study site is a habitat mosaic with home gardens, agricultural lands, isolated woodlands undergoing frequent anthropogenic disturbances, and many other forms of modified land-cover types.  For instance, K. hardwickii is found in both subtropical and tropical China, and inhabits both forested and agricultural habitats, and forages around home gardens, paddy fields, and rural human settlements (Smith & Xie 2008).  In Southeast Asia, K. hardwickii has been recorded from primary forests, secondary and disturbed forests, and montane forests (Rosell-Ambal et al. 2008).  Throughout the overall distribution, K. hardwickii occurs along a broad elevation range (60–2,060 m) (Bates & Harrison 1997).  Our observation is the first documentation of K. hardwickii from lowland rainforests of Sri Lanka, which in combination with its historic records from montane humid forests and dry mixed evergreen forests may suggest that this bat occupies a wider range of ecoregions within Sri Lanka similar to its biogeography in eastern and Southeast Asia.

Kerivoula hardwickii inhabits a wide variety of roosting habitats.  Most often, they are found in buildings (both abandoned and those occupied by humans), large dead or dry leaves that are hanging downwards (which conforms with our observation), clusters of dead leaves, hollow tree trunks, tall trees and dense bushes, and bamboo thickets (Bates & Harrison 2000; Francis 2008; Rosell-Ambal et al. 2008).  A unique roosting habit of K. hardwickii has recently been documented from Southeast Asian island of Borneo where the bat roosts inside aerial pitchers of Raffles’ Pitcher plant (Nepenthes rafflesianaelongata).  This is considered a resource-service mutualistic association where bat excreta provide nitrogen for the plant and the aerial pitcher shelters and protects the bat from predators (Bauer et al. 2011; Grafe et al. 2011).  In Sri Lanka, K. hardwickii has not been documented in pitcher plants so far.  Although pitcher plants are abundant in and around our study site, we did not find K. hardwickii to associate pitcher plants for roosting purposes.

 

 

 

 

 

Table 1. Morphometric variables recorded on Kerivoula hardwickii specimen recorded from Thoranagoda area, Sri Lanka, in this study, and also Phillips (1935), Bates & Harrison (1997) (measurements in mm.).

 

Measurement

2017

1935

1997

Head & Body length

40.37

43

39.0–55.0

Ear length

12.53

32

11.0–15.0

Ear width

6.20

-

-

Tragus length

5.98

-

-

Tragus width

1.16

-

-

Forearm length

32.47

32

31.7–36.0

1mt thumb +1st claw length

5.00

-

-

2nd metacarpal

33.42

-

-

3rd metacarpal

34.77

-

30.9–38.1

4th metacarpal

33.64

-

-

5th metacarpal

31.41

-

-

1ph 3mt length

14.22

-

-

2ph 3mt length

20.13

-

-

1ph 4mt length

9.53

-

-

2ph 4mt length

9.54

-

-

1ph 5mt length

8.24

-

-

2ph 5mt length

9.93

-

-

Wingspan length

230

-

-

Penis length

3.50

-

-

Penis width

1.19

-

-

Testicle height

1.54

-

-

Testicle width

1.33

-

-

Tibia length

17.21

-

-

Calcar length

13.44

-

-

Hind foot length

6.70

5

5.0–8.0

Tail length

38.50

-

35.0–43.0

 

 

 

Table 2. Detailed morphological features of Kerivoula hardwickii recorded from Thoranagoda area, Sri Lanka, in this study.

 

Morphological characters

Present specimen (Male)

Nose shape

Simple nostrils.

Head

Muzzle relatively small; Eyes small; The face covered in hair except for the nostrils, which are angled slightly downwards and outwards; the whiskers are conspicuous and protrude beyond the hairs on the snout.

Ears

Mostly naked but dark brown colour few short hairs present, Relatively large, funnel-shaped, tip-rounded.

Tip of the ear

Hair absent.

Tragus

 

Long and attenuated, narrowing gradually to a sharp point. A prominent notch present. Slightly concave, with a less angular tip.

Chin

Light brown, few short hairs present around the chin.

Throat

Light brown, few short hair present

Dorsal area

Dark brownish to grey or light brown, hair present throughout head and body.

Ventral area

Dark brown hair present in the nape and the chest. Light grey and light brown hair present on the abdomen.

Ante-brachial membrane

Present (Semi- transparent, thin in texture)

Radio metacarpal pouch

Absent.

Wing membrane

Well developed; the patagium and the skeletal elements supporting the patagium are naked. The wings and interfemoral membrane are brown; nearly transparent.

Forearm; 1st, 2nd, 3rd, 4th and 5th, metacarpals; 1st, 2nd, 3rd, 4th, and 5th phalanx to 1st, 2nd, 3rd, 4th, and 5th metacarpals

Naked.

Dorsal surface of tibia

Light brown, short hair present.

Inter-femoral membrane Dorsal area

Light brown, short hair present.

Inter-femoral membrane Ventral area

Light brown, short hair present.

Wing attached to

The base of the outer toe.

Penis (Foreskin)

Light brown, short hair present.

Testicles

Light brown, short hair present.

Anus

Light brown, short hair present.

Hind feet

Well-developed, light brown short hair present.

Calcar

Well-developed, light brown short hair present.

Tail

Enclosed with Inter-femoral membrane

 

 

 

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