Bats are delicate creatures, reviled by humans, driven out of their habitat wherever they are found,and yet they perform many functions that make them our strong allies. Evelyn Yu reports.

The scene before the small group that stole quietly into the abandoned brick house, in Tai Po, might have put them in mind of something straight out of a horror movie. Among the rafters of an inner sanctuary of an old house, a hundred or more dark figures hung in peaceful repose - bats. A slight movement and the hundred dark heads snapped alert, tiny eyes glowing in the dim light.

Since ancient times, humans have viewed bats as fell demons of folklore, creatures of the underworld, omens of transformation, and bringers of death. They are carriers of rabies, and of other afflictions and in popular culture, inextricably linked to vampires. Humans drive them away with zeal wherever they find them, so that governments in many countries and regions had to declare bats protected species to save them from extinction.

The people, living in a small village of Tai Po, are none too happy about this, for this is the village where more than 10 years ago, Himalayan leaf-nosed bats took over that abandoned brick house, at arms-length from a house currently occupied.

The irony stands out, while the city was rattled by the possibility of the first locally transmitted cases of the Zika virus, a pandemic that could cause babies to be born with small size of brains and heads. Bats are among our greatest allies against the mosquitoes that play a predominant role in spreading the Zika virus. A single insect-eating bat can catch and eat more than 3,000 mosquito-sized insects in a night.

All 27 local species of bat are insectivores and frugivorous (fruit eaters). The Himalayan leaf-nosed bat is one of the largest among insectivores. There are no blood devouring bats here. Of more than a thousand known species of bats, only three are known to consume blood, and they're confined to Central and South America.

Yorkie Wong, a conservation officer at the Kadoorie Farm & Botanical Garden, who is responsible for looking after the bats in the community, notes that when members of the conservation team appear, the neighbors close their windows. There're good reasons to steer clear of bats as they are wild animals and they do carry diseases. Anyone bitten by a bat needs to go to the doctor, especially if saliva from a bat comes close to a person's mouth, eyes, nose, or a fresh wound. Saliva from a rabid bat, left untreated, is likely to be fatal.

Gary Ades, head of the Fauna Conservation Department at Kadoorie Farm & Botanic Garden, said if bats are left alone, they rarely affect people nearby. Dreadful virus transmission happens only rarely and in Hong Kong it's been many years since there's been a reported case of rabies in humans from any source.

The benefits from the bat population, Ades claims, are far greater than any known harmful effects. Bats play a critical role not only in controlling harmful insects, they also play a key role in plant pollination.

"Fruit bats that eat nectars have their noses and mouths soaked with nectar and pollen, which assists pollination as they fly from flower to flower," said Ades. Taking the fig tree as an example, Ades added that the plants rely heavily on seed dispersal resulting from the activity of bats. In a single night, fruit-eating bats can drop thousands of fig seeds.

It's reported in local media that there are over 30,000 bats in Hong Kong. Ades thinks that the number, which counted manually in winter when bats are in hibernation, gives only a small part of the picture. He believes the actual number is much greater.

They are around us, yet we don't realize they're there, because they are so tiny. The Japanese pipistrelle is one example. It's one of the most common bats in urban areas, but hard to spot because it's only around 4 centimeters long. The largest bat Rousettus leschenaultii in Hong Kong has a body length of 13 to 14 cm, making it easily being mistaken for a bird.

Having a hard time

About half of the terrestrial mammals in Hong Kong are bats, protected under the Wild Animals Protection Ordinance.

Ades noted that none of the 27 species of bats in Hong Kong are considered endangered or threatened. Bats are under government protection because they are vulnerable even to minor disruptions of their habitat.

The Agriculture, Fisheries and Conservation Department (AFCD) stated in an emailed response to China Daily, that in summer, reproducing bats may abandon their young or relocate if their roosts are disturbed. The ordinance prohibits anyone from disrupting the habitats without a permit. The prohibition covers hunting, selling, exporting, controlling or possessing any protected animal. Violators can find themselves facing a year in jail and a HK$100,000 fine.

Comparing to the natural predators like snakes, owls and falcons, bats are under greater threats from human.

In Hong Kong, bats are losing their habitats due to human encroachment. Some are killed because they are seen as pests that devour food crops. Some are driven out by urbanization.

In Indonesia, Thailand, Vietnam and in other Pacific countries and regions, bats form part of the human diet. In Palau, an island country in the western Pacific Ocean, fruit bat soup is served as a local signature dish to hundreds of thousands of visitors every year.

The Wild Animal Rescue Centre in Kadoorie Farm & Botanic Garden receives 50 to 60 injured bats needing help every year.

"We once received over 20 bats trapped in a net in one go." Ades said. Incidents of this sort are more likely around Spring Festival, when farmers try to reserve their mandarin trees and flowers for sale.

"We understand that farmers are keen to protect their crops, but we can come up with a more environmentally friendly waysuch as using nets made from strands, so bats can see them better when they are flying," said Ades.

Human-nature conflict

Amid the human encroachment into bat habitats, bats are seen more often occupying residential and even heritage buildings. They prefer the old Chinese-style buildings with wooden beams that are perfect for roosting.

Ades added that residents who find the bats in their houses should stay calm, don't panic, open doors and windows. Bats are nocturnal animals that navigate using auditory echolocation. They'll find their way out at night.

AFCD cautions that if people come into contact with bats (or any wild animals) or their droppings, they should wash themselves thoroughly with soap. Surfaces of objects that have been in contact with bats or their droppings should be disinfected with a 1:50 bleach solution.

There have been reports of bats roosting in old, vacant buildings in Sai Kung and Ma On Shan. The elderly, indigenous owner of the abandoned house in Tai Po, was dismayed to discover dozens of bats roosting in the beams of her house. She called AFCD right away.

AFCD commissioned Kadoorie Farm & Botanic Garden to come up with ways for humans and bats to coexist. Kadoorie talked to the elderly woman and her family, pointing out that in the ancient Chinese culture bats are actually treated as harbingers of good fortune. The ideogram for bats and the pronunciation of the Chinese word are very similar to "luck" in Chinese. That's why bat images were embroidered on pillow covers or carved into furniture in ancient times.

Next to the brick house is the elderly owner's ancestral hall. She was worried the bats would find their way there. Kadoorie Farm helped her to install a skylight, so the bats will stay out.

A thick layer of saw dust is scattered on the floor to reduce the smell of the bat droppings.

Yorkie Wong told China Daily that for every three or four months they will come to clean out the bat guano. It's rich in nitrogen and can be turned into fertilizer. Kadoorie Farm sells it to visitors to the farm and uses the proceeds to protect and maintain rundown brick walls of the house where the bats roost.

The maintenance work must await the winter months, when bats have fled to caves and tunnels to hibernate. AFCD must be consulted prior to any construction or demolition work proposed to buildings that are known to have bats. With very keen ears bats can be disturbed by the slightest turmoil.

Much as Ades would like to change community attitudes, problems persist. "Bats are having a hard time because of people's misunderstanding," said he.

Contact the writer at

evelyn@chinadailyhk.com

(HK Edition 09/22/2016 page8)