IN A visit to Davao City a few years ago, our group decided to explore Samal Island. Officially called the Island Garden City of Samal, it is a few minutes ride by ferry or passenger boats from the Sasa Wharf in Davao City. Upon reaching the island, we were told that one of the must-see attractions are the bats. Unfortunately, bad weather prevented us from reaching the bat caves.

I was reminded of this visit to Samal Island when I read a news story about the bats in the city. The story said that the population of the bats, scientifically called Geoffrey’s rousette fruit bats, has increased. They are now estimated to number 2.5 million, up from about 1.8 million a decade ago. The bat sanctuary which we failed to reach during our visit in the island is called Monfort Cave. In 2010, the Guinness World Record officially recognized the Monfort Bat Cave as the largest fruit bat colony in the world.

Why is the increase in bat population such a big thing? Why save the bats in the first place? They are creepy creatures which are more feared than loved (except for Batman). They are decorative fixtures during Halloween and associated with blood-sucking vampires. Well, that’s because they have a very important part in an ecosystem. Fruit bats have a critical role in the pollination of trees and dispersal of seeds. In Samal, they are needed to help pollinate high-value fruits such as durian and wild banana. Furthermore, their waste, called guano, is a potent organic fertilizer.

Bats are important not just in Samal Island. According to the website, more than 1,390 species of bats around the world are playing ecological roles that are vital to the health of natural ecosystems and human economies. Many of the more than 1,390 bat species consume vast amounts of insects, including some of the most damaging agricultural pests. According to the USGS, bats save US agriculture billions of dollars per year in pest control estimated to be worth over $3.7 billion per year, and possibly as much as $53 billion.

Bats are often considered “keystone species” that are essential to some tropical and desert ecosystems. Without bats’ pollination and seed-dispersing services, local ecosystems could gradually collapse as plants fail to provide food and cover for wildlife species near the base of the food chain.

A good example is the great baobab tree of the East African savannah. It is so critical to the survival of so many wild species that it is often called the “African Tree of Life.” Yet it depends almost exclusively on bats for pollination. Without bats, the Tree of Life could die out, threatening one of our planet’s richest ecosystems.

Sadly, bat populations are on the decline. Many bat species around the world are vulnerable or endangered due to factors ranging from loss and fragmentation of habitat, diminished food supply, destruction of roosts, disease and hunting or killing.

The International Union for the Conservation of Nature (IUCN) currently lists 24 bat species as Critically Endangered, meaning they face an imminent risk of extinction. Fifty-three others are endangered, and 104 bat species are considered vulnerable.

So, if there’s a guava tree that suddenly grew in your backyard, thank the “kabag”, our native fruit bat. And please, don’t kill them.