A preliminary assessment of the bat fauna (Mammalia: Chiroptera) of Murlen National Park, Mizoram, India: distribution, morphology, and echolocation

: As part of a faunal documentation work in Murlen National Park in Mizoram, two field surveys were conducted in the park area and its immediate periphery which resulted in capture of 39 individuals of bats. Based on these captures and a previous published record, 14 bat species belonging to nine genera and three families were recorded from the study area. Despite lesser sampling coverage and shorter duration of the surveys, uncommon and little-known species like Arielulus circumdatus, Kerivoula cf. hardwickii, Myotis annectans, Myotis montivagus , and Mirostrellus joffrei were recorded, thereby highlighting the rich assemblage of chiropteran fauna and also the need for effective protection of the area. Based on the collected samples, five species— Rhinolophus affinis, R. perniger , Myotis annectans , Pipistrellus javanicus , and Mirostrellus joffrei —are first recorded from Mizoram state. The echolocation call structures of four of the recorded species from the study area are also presented. We have also provided an updated checklist of the bat fauna of Mizoram state comprising 35 species of five families.


INTRODUCTION
Murlen National Park is one of the ten protected areas in Mizoram and is the second National Park in the state.Encompassing diverse vegetation from tropical, semi evergreen to sub-montane forest, the Park has a relatively pristine ecology.Considering its contiguity with Kachin Hills in Myanmar and relatively intact nature of forest, the area has the potential to harbor a rich assemblage of fauna including a high diversity of mammals (Saikia & Bal in press).However, information on faunal diversity of the Park is scanty except for a select group of vertebrates (Kaul et al. 2001;Mandal et al. 2007;Saikia et al. 2021;Bal et al. 2022a,b;Bal & Giordono 2022;Lalramsanga et al. 2022).Bats are one of the least known mammalian groups from Mizoram with only 29 authentically recorded species (Dobson 1874;Bates & Harriosn 1997;Mandal et al. 2007) and information on the bat diversity from protected areas of the state are nearly nonexistent.The only report on the bat fauna of any protected area of Mizoram pertains to Lengteng Wildlife Sanctuary, wherein nine species of bats were reported (Vanlalnghaka 2013).However, considering the inclusion of extralimital species like Rousettus aegyptiacus and Rhinolophus hipposideros and lack of taxonomic rigor of that study, the identity of several recorded species remains to be verified.In order to fill the biodiversity information gap and consequently to help the Park authorities with better management plan of the resources, a series of faunal surveys were initiated by the North Eastern Regional Centre (NERC) of Zoological Survey of India, Shillong.As part of this survey, the first author conducted sampling in the Park and its immediate surroundings during October 2018 and March 2022.Based on the collected specimens from the aforementioned surveys and record of a single species in Mandal et al. (2007), a preliminary assessment of bat diversity in Murlen National Park and its environ has been presented.Additionally, we provide the echolocation call structures of free flying individuals of four of the recorded species from the study area.An updated checklist of the bat fauna of Mizoram comprising 35 species of five families is also provided.

Study area
Murlen National Park is located in Champhai district of Mizoram state in India adjacent to the Chin Hills of Myanmar.The Park encompasses an area of 100 km 2 spreading between 23. 53-23.70 N and 92.21-92.45E (Environment, Forest and Climate Change Department, Govt of Mizoram 2017) (Image 1).It was declared as National Park vide notification No.B.12012/5/99-FST dated 24 January 2003.The Park area spreads over a significant elevation range from 400-1,900 m.Vegetation is tropical, semi-evergreen and sub montane forests dominated by Quercus sp., Schima wallichai, Betula sp., Michelia champaca, Pinus kesiya, Prunus sp., Myrica sp., Rhododendron sp., Saccharum sp., and varieties of orchids (Kumar et al. 2018).

Field sampling and species identification
Field samplings in the National Park area and its immediate surroundings were conducted in October-November 2018  hardwickii and two Rhinolophus affinis.Fifteen of those individuals were retained as vouchers and rest were released at the capture sites.No visibly pregnant or lactating females were retained as vouchers.Captured animals were handled following standard methods in mammalogy (Sikes & Animal Care and Use Committee of the American Society of Mammalogists 2016) and vouchers were deposited into the North Eastern Regional Centre of Zoological Survey of India, Shillong for further investigations.

Echolocation call analysis
The ultrasonic calls at the sampling site were recorded with an Anabat Walkabout detector (Titley Scientific, Brendale, Australia).As the primary purpose of the survey was to document and provide unambiguous identification of species through specimens, we recorded calls by placing the bat detector in front of the nets.Calls recorded before captures were attributed to that particular individual.Although this method is prone to ambiguity in call identification and attribution, the benefit is that the calls recorded were more representative of search phase calls.Calls that are recorded upon release (the standard protocol) are rarely representative of search phase calls rendering them less useful for acoustic identification of bats recorded in free flight.
The recordings were carried at a sampling rate of 500 KHz and analyzed using Raven Pro 1.5.0 (Cornell Lab of Ornithology, Ithaca, USA).From up to 15 pulses that appeared to represent search phase calls (with short terminal narrowband FM tails), we measured start frequency (high frequency, SF), end frequency (low frequency, EF), peak frequency (PF), bandwidth (BW) and duration (D) from a spectrogram of FFT size 1024 with 95% overlap and a Hanning window.For rhinolophid bats, the measurements were extracted from the second harmonic, whereas for all other species, the first harmonic pulses were measured.

The checklist
The updated checklist of the bat fauna of Mizoram state is based on all published records till October 2023.The locality records mentioned are essentially based on Bates & Harrison (1997) and Mandal et al. (2007) updated with any succeeding publications.The chiropteran collection at NERC, Shillong is also examined and included wherever applicable.Only those published records authenticated by vouchers are taken into consideration.

RESULTS
Thirteen bat species belonging to three families were recorded from inside the Park and its immediate surroundings.Photos of the species are in Images 3 & 4, and their morphological and anatomical measurements are provided in Tables 1 & 2, respectively.The echolocation call parameters of four species, viz., Rhinolophus affinis, Mirostrellus joffrei, Myotis annectans and Myotis montivagus have been provided in Table 3.
We have also provided a consolidated checklist of bats of Mizoram in Appendix 1.
Image 2. Landscape in some of the sampling localities.© Uttam Saikia.Echolocation call: The average echolocation call peak frequency was recorded at 88.79 kHz (Table 3; Image 5) which is similar to that recorded in western Himalaya (88 kHz, Chakravarty et al. 2020) and southeastern China (Jiang et al. 2008).

Journal of Threatened
Remarks: First report of this species from Mizoram state.Apparently widespread in the area as call signatures matching the above described structure were recorded in several other places in the periphery of the Park.Remarks: Individuals were caught in mist nets while coming to drink around an artificial water source.The specimen was caught in a harp trap set across a narrow forest trail dominated by bamboo.Our specimen apparently belongs to the K. hardwickii complex and actual identity of the specimen is still under investigation.3; Image 5).The calls were similar to those reported from western Himalaya (Chakravarty et al. 2020) and northern Vietnam (Görföl et al. 2020).

2024)
Echolocation: Short duration (2.6 ms), broadband calls (43-95 kHz) calls were recorded with a mean peak frequency of 51 kHz (Table 3; Image 5).The calls presented here are the first recordings of this species from India and are similar in structure and frequencies to closely related   Remarks: The individual was caught in a mist net near an artificial water source.A few other non-reproductive females were also caught at the same spot and were released.This is the first record of this species from Mizoram.

DISCUSSION
Water is a critical resource for wildlife.During the drier period of January-April, most of the water sources in Murlen National Park and its surroundings dry out except for scattered water puddles in the streambeds.The villagers also construct some ponds in the Jhum fields for irrigation and fishery purposes.These water sources attract a number of bat species offering excellent opportunity of studying bats.In spite of our limited area coverage and short study period, we could record 12 species of bats in three families out of which five namely Rhinolophus affinis, R. perniger, Myotis annectans, Pipistrellus javanicus and Mirostrellus joffrei are new additions to the state of Mizoram.Sphaerias blanfordi was already reported from the Park (Mandal et al. 2007) indicating a very diverse bat community in the study area.Among the presently recorded species, Mirostrellus joffrei was considered as a rare species and only represented by a few museum specimens until recent times.The IUCN Red List still considers it as a 'Data Deficient' species (Görföl et al. 2016).However, after its discovery from Meghalaya, Sikkim, and from Nepal (Saikia et al. 2017), it was subsequently reported from Uttarakhand (Chakravarty et al. 2020) and Manipur (Saikia & Meetei 2022).The current record from Murlen further underscores the fact that this bat is more widely distributed in the Himalayan region and in the southeastern Asia.Another little-known species recorded in the study area is Myotis montivagus which is also currently recognized as 'Data Deficient' by the IUCN

J TT
Red List (Görföl 2020).Primarily known from scattered records from southern China, Myanmar, Vietnam, and Laos, this species is thus far definitively known only from a few localities of Mizoram in India.We characterize the echolocation call structure of free flying individual of this species from the area.It may be noted that another two species with taxonomic ambiguity, e.g., Hipposideros cf.larvatus and Kerivoula cf.hardwickii have also been recorded from Mizoram during the aforementioned surveys.However, the taxonomic status of H. larvatus s.l. in northeastern India is uncertain (Thabah et al. 2006) and a thorough integrative taxonomic reassessment is required.Similarly, the identity of Kerivoula specimen from Murlen NP also needs careful investigations as apparently it belongs to the cryptic K. hardwickii complex.As a derivative of the study, we also recorded the bat echolocation calls at our sampling sites although it was not meant for an echolocation call library.Even though a large number of calls were recorded in each sampling sites, due to difficulty in attributing a particular call to a free flying species, we provided the call structure details of only four species which we could attribute with a fair degree of certainty.Standardizing the recording protocols to obtain the "most natural" search phase calls remains another avenue of future research.
and March 2022.Bats were trapped at several localities in the immediate periphery of the Park, i.e., Murlen village and adjacent agricultural areas (23.64561 0 N, 93.296179 0 E, 1,580 m; 23.66166 0 N, 93.28333 0 E, 1,345 m) and along the Vapar-Murlen road (23.66403 0 N, 93.29623 0 E, 1,430 m) and a Forest Camp (Tuikual Duty Post) in the Park area (23.64464 0 N, 93.29786 0 E, 1,640 m) (Image 1).Mist nets (6 x 2.5 m and mesh size 16 x 16 mm, Ecotone Poland) and one two bank harp trap (Austbat, Australia) were deployed.Mist nets were set near water holes, across streams especially during the dry period of March 2022 and kept open for about three hours after sunset (Image 2).The harp trap was set across possible flight paths inside forest and forest openings and placed overnight.A total of nine nights of bat trapping were conducted.Thirty-nine individuals of bats were captured.Almost all the bats were captured in mist nets except for one individual of Kerivoula cf.

25424
Image 1. Map of Murlen National Park and surrounding areas showing sampled areas (red stars).

10. Myotis montivagus (Dobson, 1874) (Burmese-whiskered Myotis) Material examined: 1ό
, 1ϙ, V/M/ERS/697(Fig 4I),  704, 20.iii.2022,nearMurlenvillage,Vapar-Murlen road  (1,480 m), Champhai district, MizoramRemarks: A globally Data Deficient species, this bat was reported only from Mizoram state in India thus far.A possible specimen of this species has been recorded recently from Siju cave in Meghalaya(Kharkongor et al. (Saikia & Meetei 2022)0)elatively long (7.2 ms), largely FM but with a short QCF ending, typical of some Himalayan and Southeast Asian myotids (for example, Myotis siligorensis,Surlykke et al. 1993).End frequency (EF) which is less variable than peak frequency in Myotis spp. was recorded at an average of 32.27 kHz (Table3; Image 5), which is lower than that recorded in western Himalayas (36.22 kHz,Chakravarty et al. 2020)and Cambodia (38 kHz,Sophany et al. 2013).However, the western Himalayan specimens are likely to be revised to M. sicarius(Görföl et al. in prep).Nonethless, the differences in call frequencies are likely due to the different recording scenarios.The calls recorded in western Himalaya and Cambodia come from handreleased bats while our calls were recorded in free flight.Remarks:This is the first report of this species from Mizoram and recently been reported from neighboring Manipur(Saikia & Meetei 2022).