The Secret Service of Bats

Danielle Fibikar holding a greater bulldog fishing bat at VIERS

This summer, students attending the Eco-Camp at the VI Environmental Resource Station (VIERS) will be initiated into the mysteries of the bat world by Danielle Fibikar, a researcher from the College of Staten Island in New York City. Although bats are the only mammals that are native to St. John, most people don’t really know much about the intriguing work they do. 

For example, bees get most of the credit for helping immobile plants engage in sexual reproduction. During the day we can see bees busily going from one flower to another. They drink the sweet nectar and at the same time carry pollen on their hairy legs from male stamens to female pistils.

But many flowers on St. John only open at night. This is because they have evolved to attract bats instead of bees – especially Jamaican fruit bats and Antillean cave bats. Unlike bees, the bats accomplish their match-making missions under the cover of darkness.   

Night-blooming flowers attract bats by offering them nectar that smells deliciously like fermented fruit. These flowers also have to be large enough for bats to squeeze into and pick up pollen while lapping up the tasty nectar. Just like the bees, bats carry pollen on their bodies and deliver the precious powder from flower to flower. However, they can cover longer distances on their night missions and make contact with female flowers far away. This provides widely scattered trees with greater access to genetic diversity and helps them enjoy enhanced reproductive success.

In the Virgin Islands, mangoes, bananas, guavas, cashews, calabash, century plants and kapok trees all depend on bats for pollination.

Fruit-eating bats also help the trees and plants expand their territory by dropping their seeds in different parts of the island. Besides the Jamaican fruit bats and Antillean cave bats, there are also more specialized red fig-eating bats. These are quite elusive, but one night Danielle observed five of them near the Reef Bay petroglyphs, apparently lured by a fruiting fig tree.

Other bats – including the velvety free-tailed bat – prefer to hunt down insects, especially the mosquitoes that come out at dusk. Like a miniature air force they protect us from bugs that bite. According to a study by the Island Resources Foundation, a single bat can consume as many as 500 insects in just one hour or nearly 3,000 insects every night.

Unfortunately, these bats aren’t a big help in getting rid of the Aedes mosquitoes that carry the Zika virus (as well as dengue and chikungunya), because those mosquitoes are mostly active during the day.  

Danielle’s favorites are the greater bulldog bats (Noctilio leporinus), which zoom along the Lameshur Bay road just after dark, using it as a corridor from their daytime roost (a hollow tree or cave) to their offshore fishing areas. With a wingspan of up to almost two feet, these are the biggest bats found on St. John. Like James Bond, the famous fictional member of the British secret service, the males attract not one but a whole harem of available females, exuding a musky perfume that enhances their sexual allure.  

Measuring a bat's wing
Danielle has been studying St. John bats for several years as a graduate student under the guidance of Dr. Richard Veit from the College of Staten Island. She first came to VIERS for a short college course on Tropical Ecology, and fell in love with the bats. She has just received her Master’s Degree in Biology, and has written a thesis on the Ecology and Epidemiology of Bats in Temperate and Tropical Islands, which presents some of her work at VIERS on documenting bat population numbers during different seasons.

With the assistance of her colleague Pearl Cates, Danielle will conduct additional research at VIERS this summer – while also teaching campers about bats and sharing her enthusiasm for them. Recognizing that not everyone loves bats (yet), she hopes to counter some of the spooky ideas about them by emphasizing their intelligence and ecological services, as well as their musky magnetism.

Her main research activity involves setting up lightweight ‘mist’ nets across the Lameshur road to trap bats as they swoop by. One night in January 2015, Danielle caught members of all five of the types of bats commonly found on St. John. When she gets one in the net, she disentangles it (wearing thick yellow gloves) and weighs and photographs it. Then she puts a small band on it – unless it already has one. She has recaptured a number of previously banded bats, which indicates that there is a relatively small community of bats near VIERS, and that they tend to stay in the neighborhood.

The VIERS Eco-Camp is supported by the Friends of the National Park and other generous sponsors. It offers an opportunity for more than 100 local students to learn about the wildlife of the Virgin Islands (not just bats), as well as training for some not-so-secret eco-protection missions of their own.     

Danielle weighing a bat