Bat diversity in the Banpale forest, Pokhara, Nepal during spring season

: Bat research in Nepal is limited and most areas remain to be explored. Sparse research has been conducted in the Banpale forest and to improve the understanding of bat diversity, an updated species checklist was prepared. Trapping surveys using mist nets were conducted at four different locations in the forest from March to May 2018. This survey identified 55 individuals belonging to eight species within eight genera and four families. Trapping locations near less disturbed forest edges and water resources were found to have higher bat diversity compared to highly disturbed areas (e.g., landslides and logging areas). With information from survey and secondary source, we conclude that Banpale forest harbours 10 of the 53 bat species found in Nepal. We recommend adopting practices to conserve the forest from landslides and minimizing illegal logging to conserve bat forest habitats.


INTRODUCTION
Bats (Chiroptera) are highly diverse (Hutson et al. 2001;Voigt & Kingston 2016) and found throughout the globe, except in the Antarctic and a few oceanic Islands (Mickleburgh et al. 2002). They provide many ecological and economic services such as pollination, seed dispersal, agricultural pest suppression, and material & nutrient distribution (Fujita & Tuttle 1991;Kunz et al. 2011). Of the >1400 species of bats found worldwide (Simmons & Cirranello 2021), 148 are reported from southern Asia (Srinivasulu et al. 2021).
As Banpale forest lies within the boundary of the Institute of Forestry, Pokhara, it has been a hub for wildlife research and training programs. A few camera trapping, butterfly, and bird surveys have been conducted in the forest (Lama et al. 2013;Panthee et al. 2018Panthee et al. , 2019; however, extensive research predominantly focusing on chiropterans is limited. Few occasional trapping and acoustic surveys were conducted in the forest (e.g., Daniel 2007a,b;Adhikari 2008;Giri 2009;Lama et al. 2013;Bhattarai 2019 (Dobson, 1876). This study was carried out to assess bat species diversity and update the valid bat checklist in the Banpale forest.

Study area
The study was conducted in Banpale forest, Institute of Forestry, Pokhara, Tribhuvan University (28.18°N, 83.99°E), south-west of Pokhara metropolitan city-15. The institution covers 15ha of campus premises and 31.85ha of forest patches. The study site ranges from 750-915 m ( Figure 1). Banpale forest is pristine subtropical mixed forest dominated by Schima wallichii and Castanopsis indica. Other species include, Madhuca J TT indica, Diospyrus melabaricum, Dalbergia sisso, Michelia champaca, Bambusa sp., and Albizia sp. A total of 112 florae species have been reported from the area (Bhatta 2011). It is surrounded by the agricultural and grazing lands, shrubs & human settlements in the north, south & east, and gorges, crevices, rocky slopes, river & landslide areas in the west. Average daily temperature in the valley ranges 25-33 °C in summer and -2-15 °C in winter (Kansakar et al. 2004) and receives mean annual precipitation of <3,000mm (Khanal 1995).

Trapping survey
The

Morphometric measurement of bats
Vernier calipers (0.01mm accuracy) were used to record external morphometric measurements. The measurements taken include the head and body length (HBL), forearm length (FA), ear length (EL), tail length (TL), hind foot length (HF), and tibia length (TIB) (Bates & Harrison 1997). The body weight (BW) was measured using a pesola spring balance (1g accuracy). Bats were released after identifying their sex and age (Kunz & Parsons 2009) and capturing a few close up photographs with minimal disturbance. Aggressive and difficult to handle bats were released as soon as possible after identification. No voucher specimens were collected and no genetic analysis was performed during the study.

Identification of bats
Captured individuals were observed for key morphological characteristics. Identification was based on the morphological measurements (Table 1) and comparing photographs using available reference guides

Secondary data collection
Several published and unpublished reports, journal articles, newsletters, student thesis, and websites were reviewed to update the valid bat checklist in the Banpale forest.

Data analysis
Shannon diversity index (H) (Shannon & Wiener 1949) was calculated to understand species diversity in different trapping sites.
Most of the bats were captured from site A (49%) followed by site B (36%), whereas only 9% of bats were captured from site C, and lowest 5.5% from site D (Table  2). Although site B was the second most captured site, bat diversity and evenness were highest among other sites (H= 0.37, J= 0.17) followed by site A (H= 0.35, J= 0.16), site C (H= 0.22, J= 0.10), and lowest in site D (H= 0.16, J= 0.07) ( Table 2). The overall bat diversity of the forest was 1.1 and evenness was 0.5 (Table 2).
Based on the survey and literature review, the study confirmed and updated checklist of 10 bat species from the Banpale forest (Table 3). Out of these, four species are Pteropodidae belonging to four genera (Cynopterus, Eonycteris, Pteropus and Rousettus), three are Vespertilionidae with three genera (Pipistrellus, Myotis and Nyctalus), two are Rhinolophidae with genera Rhinolophus, and one Hipposideridae with genera Hipposideros (Table 3).

DISCUSSIONS
Of 10 bat species identified in this study, all (4) fruit bat species of Nepal were documented from the Banpale forest. At least one fruit bat was captured from each trapping site, reflecting their high activity in the forest. Cynopterus sphinx was captured the most, whereas Eonycteris spelaea was captured only once. Apart from forest vegetation, Banpale is also surrounded by several varieties of fruits inside the Institute of Forestry premises, e.g., Diploknema butyracea, Diospyros malabarica, Psidium guajava, Magnifera indica, Bombax ceiba, Elaeocarpus sphaericus, Litchi chinensis, Musa sp., Oroxylum indicum and Neolamarckia cadamba. These fruit plants are the most preferable diet for fruit bats in Nepal (Sharma 2016), whereas species like Musa sp., and Schima wallichii, abundant in the forest, are preferred roosts for the tent making bat, Cynopterus sphinx (Acharya et al. 2010). As Pteropus giganteus, whose nearby colony is 3.1km away, was observed travelling through the edge of the forest for foraging, perhaps cave dwelling bat species; Rousettus leschenaultii and Eonycteris spelaea also use Banpale forest as foraging route, as there is no cave in the forest (Sharma et al. 2018a). Similarly, the foliage roosting bat Cynopterus sphinx may use the forest as roosting site, since it has smaller foraging range (Marimuthu 1998;Nair et al. 1999) and was previously recorded roosting in Schima wallichii in the forest (Giri 2009). The forest vegetation is likely to host suitable roosting sites for this species. Hence, the varieties of food resources around J TT Table 1  Of the six insectivorous bat species, three belong to the Vespertilionidae family, two to Rhinolophidae, and one to Hipposideridae. Although Pipistrellus sp. has remained unidentified, we can extrapolate the unidentified species to be Pipistrellus coromandra, previously recorded in the forest by Daniel (2007a,b); however, its morphological measurements, distribution ranges, and echolocation parameters overlap with Pipistrellus javanicus (Srinivasulu et al. 2017). Further genetic analysis or cranio-dental characteristics is required for confirmation. It is also the most captured insectivore. High capture from the forest could be due to its diverse roosting and feeding habits; as it is found to roost in a wide variety of roost sites such as tree cavities, buildings, rock cervices, cracks in walls, beneath slates, and within cavity walls (Avery 1991;Jenkins et al. 1998), which are prominent in and around the forest and provide varied habitats (Russo & Jones 2003). Other two vesper bat species were Nyctalus noctula and Myotis sicarius. Nyctalus noctula is a high elevation bat (Acharya et al. 2010) and little is known about its distribution, hence it is considered 'Data Deficient' in the National Red List (Jnawali et al 2011). Seasonal migration is common to some high elevation bats, especially to the female population to escape from seasonally harsh weather conditions, scarcity of foods, and to find suitable roosts in milder climate (Fleming & Eby 2003). Female Nyctalus noctula also undergo seasonal migration in the lower elevational regions during winter (Furmankiewicz & Kucharska 2009). Here both captured females during March suggest they could be migratory individuals. Likewise, Myotis sicarius is 'Vulnerable' globally (Srinivasulu & Srinivasulu 2019) as well as nationally (Jnawali et al. 2011) and endemic to southern Asia (Bates & Harrison 1997). It is generally found in hilly forests and faces massive threats due to habitat alterations and deforestation, and hence is only known to be present in protected areas and forests (Molur et al. 2002). Low capture of these two species could be due to their rarity. Even though Hipposideros armiger and Rhinolophus affinis are mainly cave dwellers, a few individuals were captured from the forest. Both of these species are widespread throughout Nepal, roost on a wide variety of sites (caves, tunnels, old houses, and temples; Acharya et al. 2010), and feed on a diverse array of insects (Zubaid 1988). As there is no cave in the forest, they might use tree cavity or rock cervices as a roosting site or use the forest as a foraging ground. Only one individual of Rhinolophus luctus was captured throughout our study period. It is solitary and roosts in several roost types; old houses, tree cavities, tunnel, mines, holes, and caves (Csorba et al. 2003;Baniya et al. 2019). Perhaps due to its lone roosting behavior and variety of preferred habitats, it was captured only once from the forest. Further, the availability of roost sites Table 3. Updated bat checklist of Banpale forest, Institute of Forestry, Pokhara, Nepal. "LC" indicate least concern, "DD" as data deficient, and "VU" as vulnerable.  (Racey & Swift 1985;De Jong & Ahle´n 1991;Jenkins 1998) could be the main reason for the presence of these insectivorous bats in the forest. Bat species diversity and richness were unevenly distributed within the Banpale forest. Site B was the most diverse with eight species recorded, followed by Site A with seven, while sites C and D had three and two species, respectively. Site B is located in the forest trail near the edge between forest, college quarter, and nursery site, and is relatively less disturbed compared to sites C and D. Likewise, site A was near the water resource in the middle of the forest, which may account for high bat density. Anthropogenic disturbances such as illegal logging were prominent in site C (edge between forest and human settlements), and site D was located near a landslide area which may account for low bat diversity. In consonance with these findings, bat diversity was also found to decrease due to logging activities (Danielsen & Heegaard 1995;Brosset et al. 1996;Clarke et al. 2005;Meyer et al. 2016;Sharma et al. 2018b), and landslides (Vanlalnghaka 2013). Bat species diversity and composition in forests have been studied from different parts of the world (Korad et al. 2007;Loayza & Loiselle 2009;Shafie et al. 2011;Thapa et al. 2012b;Deshpande 2012;Korad 2014Korad , 2018Tshering et al. 2020).

Revision of bat species from the Banpale forest
A few species have previously been reported from the Banpale forest. Daniel (2007a,b) reported Pipistrellus coromandra, and later Adhikari (2008) supported this finding. Giri (2009) reported Cynopterus sphinx, Rhinolophus affinis, and Pipistrellus pipistrellus; however, the existence of Pipistrellus pipistrellus has not been documented from Nepal (Acharya et al. 2010;Thapa 2014); moreover, occasionally reported from southern Asia (Hutson et al. 2008). This report lacks photographic evidence, and we suggest the species identified could have been Pipistrellus coromandra, reported earlier by Daniel (2007a,b). Cynopterus sphinx was reported earlier by Bhattarai (2019) (Bates & Harrison 1997). Due to unpublished sources, lack of photographic evidence, and taxonomic details, we also doubt the record of these species from the forest. Pteropus giganteus was observed flying through the edge of the forest; foraging in the forest, and an electrocuted individual was also sighted inside the campus premises. Further, Rousettus leschenaultii was recorded by Acharya, P.R. (as personal communication), Eonycteris spelaea by Sharma et al. (2018a) (part of this study), and Rhinolophus luctus by Baniya et al. (2019). Both Rousettus leschenaultii and Rhinolophus luctus were also recorded during our study period. Here, we represent the first record of Eonycteris spelaea from the Banpale forest and western Nepal as well as fourth record for the country (Sharma et al. 2018a); the first record of Nyctalus noctula and Myotis sicarius from the Banpale forest and second record from the Pokhara valley; previously recorded at Sudame by Csorba et al. (1999); the first record of Hipposideros armiger; second record of Rousettus leschenaultii and Rhinolophus luctus from Banpale forest. The record of these species from the forest indicates that they might have been overlooked during previous mammal researches or sparse and inconsistent bat surveys in the forest. All of these findings sum up a total of 10 bat species from the Banpale forest.

CONCLUSION
Comprehending our study and data, we can generalize the Banpale forest to be rich in bat diversity harbouring either roosting habitat or foraging grounds for both fruit dependent as well as insect dependent bats. Availability of fruits, good insect abundance, and the presence of edges, water resources, crevices, and cavities might be a vital reason for high bat diversity in the forest. Based on survey efforts and literature, we confirmed the record of 10 species of bats in the forest, indicating relatively high density in terms of its geographic extent. Bat diversity in the forest was noted to vary among sites, with maximum diversity near the forest edge, water resources and less disturbed areas, and lower diversity in the landslide and logged areas. Hence, this study recommends the campus committee adopt practices to conserve the forest from landslides and minimize illegal logging. This study did not capture bats from high tree canopies nor record echolocation calls, and was limited to only two months. Surveying of bats throughout the year with the