Bat Species Composition, Diversity and Abundance at Bacolod City National High School


AuthorsJerelle S. Espinosa, Katrina G. Medez, Mathie Joellie B. Rivera, Erick D. Degalicia, Norilyn O. Belonio, Eliana Marie G. Caya, Phillip Raymund R. De Oca, Philip Godfrey C. Jakosalem
Volume2
Date PublishedDecember 18, 2023
Date UpdatedMay 16, 2024


Abstract

Very little information is available on bats in urban areas. The highly urbanized City of Bacolod has seen rapid development in the last 10 years. Urban green spaces are rapidly disappearing to give way to development and are now limited to city parks and private areas like school grounds. In this study, we recorded the composition, diversity, and abundance of bat species at Bacolod City National High School. Mist-netting was done on 31 net nights across accessible and densely vegetated sampling areas. A total of 202 bat individuals were captured from Cynopterus brachyotis, Ptenochirus jagori, Macroglossus minimus, Eonycteris spelaea, and Taphozous melanopogon species. The bat species diversity value was found to be 0.95, indicating very low species diversity. C. Brachyotis was the most frequently captured species, accounting for 61.9% of the captured bat individuals. In the study, the capture of P. jagori was surprising since it is known to prefer forest habitats. Likewise, T. Melanopogon individuals with distinctive morphological measurements and characteristics different from the available records of the species were also documented. Based on the findings, improvement of green spaces in schools is encouraged. Also, information gathered from this study must be communicated in DepEd learning resource materials to raise awareness about bat importance and conservation



Introduction

Bats (Chiroptera) serve crucial roles in our environment pollinating flowers and disseminating fruit seeds of more than 500 plant species[1]. These animals inhabit forested regions all over the world[2] dwelling on roosting structures, such as caves, foliage, branches, crevices, tree trunks, and hollows, for various purposes, including raising their offspring, hibernating, or seeking shelter[3].

Studies have shown that regions with abundant vegetation are home to greater variety and richness of bats and other species[4] [5] [6]. Whereas the species richness and species composition of bats were influenced by landscape characteristics (such as trees, linear vegetation, groves, and rushing and standing water)[7] In particular bat species richness is also boosted by higher forest land cover (p < 0.01) and closer proximity to wooded regions (p < 0.05) [7] as these factors are crucial to their as vegetation grows, so do the quantities of insects and fruits that bats eat [8] [9][10]. However due to increased urbanization, many bats lose their roosting locations as they rely heavily on preexisting roosting structures, natural and man-made [11].

Likewise urban habitats still persist and have potential for bat conservation[12], including schools as they offer a range of possible roosting opportunities for bats, which results in faster development of bat juveniles and less exposure to natural predators [13]. Furthermore, memoranda from the Department of Education exist, urging all public and private schools to lead the way in environmental awareness by further encouraging school-based activities such as tree planting that help preserve and protect the environment[14] [15] [16]. These issuances improve the quality of vegetation in schools as well as meeting the standards of a potential roost spot.

Bacolod City National High School is a school campus located within the City of Bacolod: a highly-urbanized city [17] [18]. that is moderately high in green spaces [21]. However, in the last 10 years, the City of Bacolod has seen rapid development [19] [20] [21] [22] [23]. Urban green spaces are rapidly disappearing, and are now limited to city parks and private areas like school grounds [23] [24] [24] [25] [26] [27]. On school grounds, information of Bat species is scarce. Hence, this study aims to record and identify the different species of bats that reside within Bacolod City National High School, determine bat diversity by using the Shannon-Wiener Diversity Index, and determine bat abundance in Bacolod City National High School.



Methodology

This study was done at the Bacolod City National High School, which is a General Public Secondary High School situated at P. Hernaez St Ext, Bacolod, 6100 Negros Occidental, Philippines. With a total land area of 15 hectares, the area comprising the whole campus has been sectioned into 4 sampling areas, namely Creek, Bacolod Arts Center Miniforest, Track Oval and Softball Grounds, Football and Baseball Grounds.



Sampling Areas

The school was assessed for the establishments of net lines, they were selected based on the accessibility of the location, across trails, along fruit trees, riparian zones, building roosting sites, and along potential flyways [1] [28] [29].

Sampling Areas
Creek
Bacolod Arts Center Mini forest
Track Oval and Softball Grounds
Football and Baseball Grounds


Materials and Equipment

The Philippines Biodiversity Conservation Foundation Inc. grants us permission to borrow all the necessary equipment to guarantee proper processing and analysis of the collected data, including mist nets around 12x5 meters in width and length, bundles of rope, bags for captured bats, Pentel pen markers, and bamboo poles 3–7 meters in length. Captured bats were identified using the Key to the Bats of Ingles and Heaney (1992). The identification of sex was determined by observing the genitalia and nipples. The age (adult, sub-adult, or juvenile) was estimated by the degree of ossification of the joints in the digits of the wings. The length of the forearm, ear, hindfoot, and total length were measured using a dial caliper, and body weight was measured using a Pesola scale.



Sampling Method

Sampling was conducted between May 2023- June 2023 within a rational time frame associated with Wildfire Gratuitous Permit No. R6-2023-002. Standard mist netting method was used for a total of 31 net nights across 4 sites. Each sampling area is composed of 4 mist nets positioned depending on the accessibility of the location, choice of height mainly depends on trees available that can support the nets, if no trees are available then the positioning of nets will be done through bamboo poles. There were instances in which two nets were deployed on one net line. Mist nets were positioned before dark (3:00PM - 5:00PM) across established trails, foliage, along fruit trees, and inside the Bacolod Arts Center. Net hours were observed and checking was done from 6:00 PM until 10:45 PM in each data collection. The establishment of nets was done in two sites regularly and sequentially from the first to the last site to cover more ground. Data collection was done in a span of 8 hours per day.



Identification of External Measurement

On identification of bat samples, the Key to the Bats of the Philippines Islands of Ingle & Heaney (1992) was used. Standard biometric measurements were determined, recorded, and referred to the bat guide to identify the retrieved bats, On measurement, total length, tail length, forearm length, hind foot length, and ear length, sex, age and weight were recorded. If the bat biometric measurements along with the physical appearances fall within the range of specific family and species of the identification guide, the retrieved bat can be identified.



Data Analysis

The Shannon-Weiner Diversity index was used to determine the bat diversity through the gathered data where p is the proportion (n/N) of individuals of one particular species found (n) divided by the total number of individuals found (N), ln is the natural log, Σ is the sum of the calculations, and s is the number of species.The equation for the index is as follows, Shannon Index (H) = - Σp¡ * ln(p¡)



Results and Discussion



Species Composition

On Table 1, Bacolod City National High School consists of 4 residents, and 1 Endemic species of bats. The Lesser short-nosed fruit bat Cynopterus brachyotis, Dagger-toothed long nosed fruit bat Macroglossus minimus, Cave Nectar Bat Eoncyteris Spelaea, and the Black bearded tomb bat Taphozous melanopogon all resident, and Greater Musky Fruit bat Ptenochirus jagori as endemic.

Table 1. List of bats recorded in Bacolod City National High School

Sub-OrderFamilyScientific NameCommon NameEndemicityIUCN Status
MegachiropteraPteropodidaeCynopterus brachyotisLesser Short-Nosed Fruit BatResidentLeast Concern
MegachiropteraPteropodidaePtenochirus jagoriGreater Musky Fruit BatEndemicLeast Concern
MegachiropteraPteropodidaeMacroglosus minimusDagger-Toothed Long-Nosed Fruit BatResidentLeast Concern
MegachiropteraPteropodidaeEoncyteris spelaeaCave Nectar BatResidentLeast Concern
MicrochiropteraEmballonuridaeTaphozous melanopogonBlack-Bearded Tomb BatResidentLeast Concern
Total Number of Species5
Total Number of Endemic Species1
Total Number of Threatened Species0

Cynopterus brachyotis

A moderately small fruit bat, belonging in the family Pteropodidae and the suborder Megachiroptera, these species of bats are known for their resiliency and strong flight ability. Classified as Least Concern on The IUCN Red List given their wide distribution all over Southeast Asia [1] .They are typically found in secondary forests, urban areas and fruit orchards, having broad snouts, and four upper and lower incisors to feed on fruit including bananas, figs and guava. Adults, especially males, have a yellow/orange ruff around their shoulder which is paler on females. Grayish brown on the chest and belly, with an orange or yellowish hue on occasion. its index claw and tail are always present, and the wing membranes are dark gray and attached to the first toe [30] [31].

Ptenochirus jagori

A fairly large fruit bat, belonging in the family Pteropodidae in the suborder Megachiroptera. These species of bats are endemic to the Philippines except in the Batanes/Babuyan and Palawan regions [1]. Typically associated in primary forests, and often present in croplands they are classified as Least Concern on the IUCN Red List .The head is large and wide, muzzle is stout, with blackish and brown skin. A wide rusty to reddish brown ruff is present on both sexes producing a distinct “sweet musty cinnamon” odor which is more conspicuous on males, pelage on chest and belly is grayish brown, wing membranes are dark gray, index claw is visible, and it's wings from the sides of its body attach to the first toe [32]. Unlike in C. Brachyotis they have four upper and two lower incisors to feed on figs and other fruit, including banana [33].

Macroglossus minimus

A small fruit bat, belonging in the family Pteropodidae in the suborder Megachiroptera. These species of bats' are known to dwell in agricultural, secondary forests, primary forests as well as other heavily disturbed areas, in Asia such as Malaysia, Indonesia , Thailand, Australia, Papua new Guinea , the Solomon Islands, and the Philippines. It's wide distribution can be affiliated from its ability to cross narrow water gaps that allows them to maintain populations on very small islands [34]. Classified as Least Concern on the IUCN Red list. Being the smallest species of Pteropopid they have elongated heads, and rounded nostrils. Upperparts are buffy-brown while the underparts are paler and greyer. Its wing membranes light brown, they Four tiny upper and lower incisors to feed on nectar and pollen [35].

Eonycteris spelaea

A fairly small fruit bat, belonging in the family Pteropodidae in the suborder Megachiroptera. These species of bats can be found throughout Asia, countries such as India, Myanmar, and Philippines, except in Batanes/Babuyan regions. Often abundant in agricultural areas and secondary forests as well as urban areas and orchards, classified as Least Concern in the IUCN Red list. They are found to have dark brown or gray fur, a fairly long muzzle and tongue. There is no claw on the second digit. And a pair of glands lateral to the anus are always present and visible. Ears and tail have moderate length, and they usually have a ruff of hairs around the neck [36] [37].

Taphozous melanopogon

Black-bearded tomb bats have a coat that varies quite a bit depending on their specific location. It comes in a variety of colors, from whitish to multi-brown or crimson. Hairs normally have a white tip and gradually become more red or brown near the base. The membrane of the tail (uropatagium) has fur. Instead of the throat sac, which would be present, there are several pores that open into the throat region. Black beards on males are believed to be seasonal. Males secrete a thick material into their beards during mating season, which is thought to be a type of pheromone that attracts females. The thick tail thins to a tip that is slightly bulbous. Right above the ankles, the wings are attached [38]

Figure 1. A. Cynopterus brachyotis, B. Ptenochirus jagori, C. Macroglossus minimus, D. Eonycteris spelaea, E. Taphozous melanopogon

There were two instances of captured bat individuals that exceeded the appropriate biometric data limit of Taphozous melanopogon. Normally, the measurement of Taphozous m. in identifying its forearm ranges 61-65mm, the ear measures 20-24 mm and body mass weighs 20-29g, while in B (figure 2) the measurement of the individual’s forearm differed and measured 68.72 mm, the ear also differed and measured 17.7 mm and the body mass weighs 31 g. The external biometric data of the Taphozous in B (figure 2) was in range with Saccolaimus saccolaimus as it fits its required measurements; however, it wasn’t considered as one as it lacked a gular pouch to be identified as Saccolaimus saccolaimus.

Figure 2. A. Well-developed gular pouch of Saccolaimus saccolaimus (photo courtesy to Ranil P. Nanayakkara), B. Captured Taphozous melanopogon that is in range with Saccolaimus saccolaimus biometric data but with non-existent gular pouch

 T. melanopogonS. saccolaimus
Total Length (mm)103-111103-117
Tail (mm)20-2520-28
Hind foot (mm)11-1515-19
Ear (mm)20-2416-20
Forearm (mm)61-6566-71
Weight (g)20-29g28-36g

Table 2. Average biometric range of T. melanopogon and S. Saccolaimus.

 T.melanopogon (?)T.melanopogon (?)
Total Length (mm)105.19104.37
Tail (mm)26.5926.65
Hind foot (mm)16.2517.65
Ear (mm)19.9917.7
Forearm (mm)69.7868.72
Weight (g)29g31g

Table 3. Captured T. melanopogon (?) individuals with distinct morphological measurements.

Species Diversity

Species diversity in Bacolod City National High School was found to be at A shannon-Wiener value 0.95 indicates very low species diversity. A value of 0.95 would mean that all the areas would almost have the same diversity of bats. It implies that there are relatively few successful species in the habitat, the environment is quite stressful and only a small number of species are truly well adapted to the environment [39]. Moreover a similar study was conducted by Bendoy et al., (2003) at the University of the Philippines (UP) Arboretum with 62 bat individuals recorded from the genera Ptenochirus and Rousettus at a Shannon Weiner value of 0.278 [40].

Abundance

A total of 202 bat individuals were captured with the most common netted species in Bacolod City National High School was the Lesser Short-Nosed Fruit Bat Cynopterus Brachyotis with a record of 125 caught making up 61.9 % of the total number of captured bat individuals. This species was found to dwell on all four sampling areas. Followed by the Black-bearded tomb bat Taphozous Melanopogon with 59 captured within the school, constituting 29.2% out of the total captured bats. Greater musky fruit bat Ptenochirus Jagori with 11 captured making up 5.4% out of the total captured, the Dagger-toothed long nosed fruit bat Macroglossus minimus with 5 captured making 2.5%, and lastly Cave Nectar Bat Eoncyteris Spelaea with only two captured making up 1% of the total captured.

Figure 3. Overall abundance of bat species recorded out of 202 bat individuals in (%).



Conclusion

In conclusion, the vast region creates multiple habitats that sustain a great variety of bat species. The assessment of bat composition , diversity and abundance in the study done within Bacolod City National High School found a considerable presence of bats across various habitats. Bats were captured at Bacolod City National High School using the mist netting method. A total of 202 bats individuals were recorded under two families composed of five species, Cynopterus brachyotis, Macroglossus minimus, Eonycteris spelaea, and Taphozous melanopogon, the four species being considered resident, while Ptenochirus jagori is endemic. The capture of P. jagori was surprising considering that the species was known to prefer forest habitats.

It was observed that BAC Miniforest has the highest count of bats with a total of 95 captured bat individuals, with five species of bats within its cover. Bat species diversity in Bacolod City National High School was found to be at a shannon-Wiener value of 0.95, indicating a very low species diversity, but higher compared to a similar study conducted by Bendoy et al., (2003) at the University of the Philippines (UP) Arboretum with only two genera of bats identified, Ptenochirus with 21 caught and Rousettus with 41 caught, and at a Shannon Weiner value of 0.278.

Taphozous melanopogon was the most abundant species in Bacolod Arts Center Mini Forest constituting 63.2% of the total bat individuals recorded in that area. Cynopterus brachyotis was most abundant among Creek, Track Oval and Football Grounds, and Baseball and Softball Grounds. Furthermore, it had the most number of documented individuals over all habitat types with a total species abundance of 61.9%. There’s also reports on the presence of individuals of Taphozous that have distinctive morphological measurements and characteristics that differ from that of T.melanopogon.



Recommendations

Based on the results, Bacolod City National High School has a very low diversity for bats, hence it is highly encouraged to promote green spaces as urban green spaces are rapidly disappearing, likewise they provide great habitats for flora and fauna alike. It is also recommended to establish Composition, Diversity and Abundance studies not only in forests but in other urban locations such as green spaces or schools as this information can be used for future conservation related projects. A study on the the presence of fruit bats and fruiting trees is recommended on whether such variables have a significant difference on their presence, as well a study involving the utilization of harp traps in Bacolod City since insect bats of different species is to be expected more in the city. To spread knowledge of the value and conservation of bats, the data from this study must be included in DepEd learning resource materials.



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