Bats of Miagao

SGF conducts annual bat counts for long-term monitoring to provide crucial baseline data for understanding bat populations and developing effective conservation strategies.

Background & History

The annual bat count is the pioneering project of SGF in the community of Miagao prior to its establishment. Throughout the years, the SGF collaborates with government agencies such as the Muncipal Environment and Natural Resources Office of Miagao and the Communinty Environment and Natural Resources Office-Guimbal.

According to the townspeople of Miagao, bats have been coexisting with the people for more than 70 years. In the year 2014 (Matias), the bat population was counted to about 5,000 individuals and more than 7,000 (Matias, 2016) individuals before they transferred from the Bubog tree (Sterculia foetida) that they used to roost last 2018. They abandoned the tree after it “died”, but the tree now seems to recover three years later.  As part of its conservation efforts, SGF continues to conduct its bat count efforts to provide baseline information to promote further studies on the bats and their associated environment.

Miagao is a first class municipality in the Province of Iloilo with 119 barangays and a total population of 68,115 with very rich historical stories to tell.

The most famous of course, is the Miagao’s Santo Tomas de Villanueva Church. constructed through forced labour from 1787 to 1797 during the Spanish period. Because of the artistic native motif sculptural relief carved on its façade, it was declared as a UNESCO World Heritage Church in 1993.

Another spectacular architecture that can be found in Miagao is the Britanico Bridge, formerly Sapa Bridge. The locals claimed that the bridge is home to mythical creatures like the White Lady and many more. But those stories only made the bridge more fascinating and authentic. It was built during the Spanish era and is located beside Sulu Garden, which was a bakery before the restaurant was constructed.

These and more old structures will capture your attention when you get to the municipality of Miagao. But nothing is more amazing than the tourist attractions brought about by nature…

Just after you arrive at the centre of the municipality, you will notice the strong smell of bat urine, not to mention the screeching sounds these bats make. But give it at least ten minutes, and you’ll just get used to the smell, like what the locals have become after decades of coexisting with bats in Miagao. You will see that most of the Agoho (Casuarina. Equisetifolia) trees and one Narra (Pterocarpus indicus) tree at the right side of Miagao Church have become the roosting sites of Common Island Flying Fox (Pteropus hypomelanus), the smallest species of its genus. That and more trees within the Poblacion area. They belong to the Old World Fruit Bats, the kind of bats that have the ability to see clearly and do not rely on echolocation to hunt for food.

P. Hypomelanus is geographically found in the Indo-Australian region, including the Philippines, Solomon Islands, and Papua New Guinea. Their body is fully furred and a noticeable golden dorsal part makes it easy to identify the Common Island Flying Fox from other species of bats, according to Ouilette (2006). This species is included in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which according to the Department of Environment and Natural Resources Administrative Order (DAO) 2019-09 is considered to be an Endangered species.

Common Island Flying Fox roosting at the Narra Tree inside Miagao Church’ gate.
Close-up shot of Common Island Flying Fox roosting showing its golden dorsal.
The Bubog tree where the Common Island Flying Foxes used to roost. New leaves can now be seen sprouting again from the tree

These bats have been coexisting with the people of Miagao for more than 70 years, according to the residents living within the area. In the year 2014 (Matias), the bat population was counted to about 5,000 individuals and more than 7,000 (Matias, 2016) individuals before they transferred from the Bubog tree (Sterculia foetida) that they used to roost last 2018. They abandoned the tree after it “died”, but the tree now seems to recover three years later.

Summary

The bar graph below shows the summarized result of the Bat population for 4 years based on the field work of the Sulu Garden Foundation and its collaborators.

The 2021 bat population resulted in a total average of seven thousand three hundred ninety-two (7,392) individuals. It was followed by the year 2022 with three thousand five hundred ninety-three (3,593) in January, thereby having a 51.39% decrease. During May of the same year, it increased to five thousand nine hundred eighty-nine (5,989) and subsequently decreased to five thousand three hundred fifty-five (5,355) in September. Hence, the year had a 66.69% increase and a 10.59% decrease respectively, reflecting changes relative to the previous data.

The following year, 2023, the bat population increased to six thousand five hundred thirty-one (6,531) on the January count with a 21.96% increase and it went down a bit in May to six thousand one hundred one (6,101) having a 6.58% decrease. After seventeen months, the November 2024 count, the bat population decreased to four thousand two hundred twenty (4,220). The latest data has a 30.83% decrease from the May 2023 count and a 42.91% decrease from the first bat count last August 2021.

Results

November

The bat population count survey for the year 2024 was conducted last November 28, 2024 in coordination with the MENRO-Miagao staff and several 4th year BS Computer Science students of UP Visayas. A total of forty-three (43) roosting trees were mapped out within the town center of Miagao with thirteen (13) various species. Fruit bats prefer trees with 0-20% damage with 48.8% bats roosting based on our findings on damage classification. The total average bat count population for the year 2024 is at four thousand two hundred twenty (4,220) from a total of forty-three (43) recorded fruit bat roosting trees. The average bat count population decreased by 30.83% in comparison to the May 2023 count.

January

The first bat population count survey for the year 2023 was conducted last January 26, 2023. It was done with CENRO-Guimbal staff. This year, there are only thirty-seven (37) individual trees left being roosted by the island flying foxes, with still fifteen (15) species. This January, the total count was six thousand five hundred thirty-one (6,531) individuals with seven hundred twenty-one (721) as the highest count on a acacia tree and the least count was fourteen (14) on a coconut tree. The bat count population increased by 21.96% compared with the last September 2022 count.

May

The second bat population count survey for the current year 2023 was conducted last May 19, 2023. This second trimester, there are forty-four (44) individual trees roosted on by the island flying foxes, with still fifteen (15) species. There was an 18.92% increase in the number of their roosting sites and there was no change in the number of species recorded, compared to last January’s data.This May, the total count was six thousand one hundred one (6,101) individuals with eight hundred fifty-seven (857) as the highest count on a mango tree and the least count was two (2) on a talisay tree. The bat count population decreased by 6.58% compared with the last January count.

January

The first bat population count survey for the current year 2022 was conducted last January 16-18, 2022. There were forty-six (46) individual trees recorded, with fourteen (14) species. This year, there are only twenty-seven (27) individual trees left being roosted by the island flying foxes, with only eleven (11) species left. The total bat population went down to three thousand five hundred ninety-three (3,593) individuals with four hundred eighty-six (486) counts on an Acacia tree as the highest count per tree and the least count was two (2) in a Mahogany tree.

May

For the 2nd trimester of 2022, the count was conducted last May 19, 2022. There were forty-eight (48) trees with eighteen (18) species recorded. This May, the total population went up to five thousand nine hundred eighty-nine (5,989) individuals with one thousand three hundred fifty-three (1,353) counts on an acacia tree as the highest count per tree and the least count was eight (2) in both neem tree and bamboo.

September

This September, the total count was five thousand three hundred fifty-five (5,355) individuals with eight hundred thirty-two (832) as the highest count on a narra tree and the least count was only two (2) on an agoho tree. The number of roosting tree species is fifteen (15) this last trimester. Eleven (11) out of the forty-one (41) roosting trees are mahogany.

The dates of the survey for 2022 were January 16-18, May 19 and September 29. The SGF staff conducted it together with MENRO-Miag-ao and CENRO-Guimbal.

There were a total of 46 individual trees recorded as the bats’ roosting sites and it consists of twenty (20) species.

The 20 species of trees are: Acacia (Samanea saman), Agoho (Casuarina equisetifolia), Bubog (Sterculia foetida), Caimito (Chrysophyllum cainito), Coconut (Cocos nucifera), Duldol (Ceiba pentandra), Gmelina (Gmelina arborea), Mango (Mangifera indica), Kamansi (Artocarpus camansi), Lanete (Wrightia pubescens), Lunok (Ficus sp.), Mahogany (Swietenia macrophylla), Narra (Pterocarpus indicus), Neem (Azidirachta indica), Payhod, Rain Tree, Sambag (Tamarindus indica), Santol (Sandoricum koetjape), Talisay and Tipolo (Artocarpus blancoi). And there was also one Bamboo grass.

The Common Island Flying Foxes’ average total population in the town of Miag-ao for 2022 is four thousand nine hundred seventy-nine (4,979) individuals. The highest average count in a tree was from the Acacia tree with eight hundred fifty-two (852) individuals and the least was from a Neem tree with only seven (7) counts.

Figure 1. the total number of bats per trimester that the count was conducted.

September

From the period of August 26 to September 3, 2021, the staff from Sulu Garden Foundation surveyed the Municipality of Miag-ao to list, identify and plot the roosting sites of Common Island Foxes on a map and count their population. There are forty-six (46) individual trees recorded as the bats’ roosting sites and it consists of fourteen (14) species. The Common Island Flying Foxes’ average total population in the town of Miag-ao is seven thousand three hundred ninety-two (7,392) individuals as of September 3, 2021. The highest count in a tree was from the Acacia tree with one thousand forty-four (1,044±4) individuals and the least was from the two (2) Agoho trees beside Miag-ao Church with only three (3) counts each.

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