Occurrence of Pipistrellus tenuis in Goalpara, Assam, India
A recent survey identified a colony of Pipistrellus tenuis (n = 5) in Kanyakuchi Pahar village (26°00’32.8″N 90°53’29.0″E), a rural remote site situated at Goalpara district of Assam. This species, commonly known as the Least Pipistrelle, was previously reported by Hinton and Lindsay (1926), Sinha (1999), Ghosh (2008), Saikia et al. (2011) and Boro et al. (2018) from different parts of Assam. The Goalpara district of western Assam is encircled by the foothills of Meghalaya to the South and the Brahmaputra River to the North possesses a variety of flora and fauna due to the dense foliage of the high forest canopy. The climatic condition of the region along with its topography favours roosting of bat population. The distribution of the bat species P. tenuis in the surveyed area has not been previously recorded. For the purpose of taxonomic identification, morphometric parameters (external and cranio-dental measurements) were compared to standard literature by Bates and Harrison (1997). Captured bat specimens (n=3) were examined at the ZSI (Zoological Survey of India), NERC-Shillong, Meghalaya. The recorded mean body weight of captured specimens was 2.61g ± 0.160 (S.D) and the mean forearm length (FA) was 27.39mm ± 0.165 (S.D). This manuscript validates sightings of this bat species at the study location, compares its morphometric and cranio-dental traits to standard literature (Bates and Harrison, 1997) for identification, discusses its distribution as well as its ecological importance.
Bats are the only mammals that can fly for long periods of time, making them the second-largest order of mammals with over 1,400 different species. The two suborders of bats, Microchiroptera (echolocating bats) and Megachiroptera (Old World bats) make up the taxonomic group Chiroptera. 127 species of bats from India were listed by Talmale and Saikia (2018) and were categorised into 41 genera and 9 families. About 39 different bat species, divided into 16 genera, are found in Assam, including 34 Microchiropteran species and 5 Megachiropteran species (fruit bats) (Ali, 2022). The Himalaya and Indo-Burma Biodiversity Hotspot, which includes Northeast India, contains 74 species of the 127 species of bats that are known to exist in India (Saikia, 2019). There are nine families in the order Chiroptera that are represented in India: Pteropodidae, Megadermatidae, Hipposideridae, Rhinolophidae, Emballonuridae, Rhinopomatidae, Molossidae, Vespertilionidae, and Miniopteridae.
With 62 species, the family Vespertilionidae (commonly known as evening bats) is the most diverse and numerous family of bats found in India (Saikia 2019; Ali, 2022). The tiniest pipistrelle found in the Indian subcontinent belongs to the Vespertilionidae family and is known as the least pipistrelle (Figs. 2 and 3). The genus Pipistrellus has 51 species worldwide, including 12 species being found on the Indian subcontinent (Koopman, 1993). It's prevalent over the majority of Southeast Asia, Southeast China, and South Asia (Simmons, 2005). This species is found in Pakistan, Bangladesh, Afghanistan, India, Nepal, and Sri Lanka (Molur et al., 2002; Das, 2003; Vanitharanie, 2006; Korad, 2007). This bat occasionally shares a roost with Indian Pipistrelles, but they don't interact with one another. They frequently form colonies of 1 to 25 individuals and are present in both woodlands and populated places and often prefer living in close proximity to human population. They build their nests in trees, leaf canopies, the ceilings or walls of buildings, and abandoned homes (Francis et al., 2010). Seasonal variations in the species' diet are evident.
It consumes a variety of insects and beetles during the monsoon and summer, and termites, cockroaches, wingless ants, and moths during the winter (Hamidullah et al., 2019).
P. tenuis are categorised as insectivorous bats in terms of preferred diet and feeding habits. A typical pipistrelle bat can often consume one-third of its body weight in insects per night, significantly lowering the number of insects. They devour a lot of insects at night, which costs the US $3.7 billion in pest control every year. It has been shown, according to the Smithsonian Tropical Research Institute and the University of Michigan that places with insectivorous bat populations greatly reduce the amount of insects and plant damage (Kalka et al., 2008). Recent study on the reproductive activity of the P. tenuis species indicate that there are two peaks between the months of July and August, and one between February and March. The greatest abundance of prey occurred during each of these times. In China and India, pregnant and nursing females have been spotted at all times of the year, proving that reproduction is possible all year long (Wilson and Mittermeier, 2019). Due to their nocturnal lifestyle and ecological diversity, bats are a fascinating group of animals as well as a difficult species to research.
A number of researchers from the Zoological Survey of India and other institutions have made significant contributions to the study of Indian bat taxonomy and geographic distribution in the post-independence era. Some of the most important revisions of the geographical range and taxonomy of Indian bats include Brosset (1962abc, 1963); Hill and Corbett (1992); Bhat and Kock (1994); Sinha (1970, 1973, 1999); Bates & Harrison (1997); Pradhan (2008); Das (2003); Csorba et al. (2003); Ramarkishna et al. (2003); Ghosh (2005, 2008); Srinivasulu (2001, 2006); Alfred, (2006). A monograph by Bates & Harrison (1997) listed 28 species of bats from Assam. Recently, there are only a few significant works on the study of different species of bats in the state of Assam by Sinha (1999), Ghosh (2008) and Boro et al. (2013; 2015; 2018), Ali (2010; 2022), Rahman and Choudhury (2017), Saikia et al. (2011; 2018; 2019; 2021).
Furthermore, little is known about the distribution and taxonomic status of bats, notably microchiroptera, in the Assam region. This article aims to investigate the distribution and current status of the Pipistrellus genus in Assam's Goalpara district. This paper on Pipistrellus tenuis occurence is the first at the study site (Fig. 1) and is based on measurements of morphometric features in comparison to current standard literature (Bates and Harrison, 1997).
Source : Occurrence of Pipistrellus tenuis in Goalpara, Assam, India | InformativeBD
