Surveying bats in Grenada

February 23, 2016 | Sharlene Santana

Grenada is a small island (344 Km2) located in the Southeastern Caribbean. Despite its small size, Grenada’s mountainous landscape boasts trees of commercially important fruits—in fact, it’s one of the leading producers of nutmeg and mace in the world. For fruit bats, this means one thing: lots and lots of food.

This past summer, University of Washington (UW) graduate student Leith Miller and I received an invitation to study Grenada’s fruit bats with Dr. Sonia Cheetam Brow and Dr. Diana Stone at Saint George’s University (SGU). Sonia and Diana are virologists at SGU’s School of Veterinary Medicine, and wanted to research viruses that may be hosted by Grenadian bats.

This research is particularly important for Grenada because bats are abundant and they often use man-made structures for roosting—putting them in close proximity to humans. Additionally, we wanted to survey what bat species live there. Very few studies have characterized the island’s bat fauna and the last inventory precedes the damage caused by Hurricane Ivan to the region.

While in Grenada, we spent a lot of time finding bat roosting sites near human-populated areas, and visited all of Grenada’s parishes to get a full coverage of the island major habitats.

Our collaborators put a lot of effort networking with locals to find bat roosting sites. While people in Grenada are very familiar with the presence of bats, locating bat colonies proved to be tricky. "First, there is little knowledge about natural roosts, with the exception of one small cave that is home to hundreds of bats (Artibeus spp. and Glossophaga longirostris)." Second, bats are considered “pests” by most locals, and any group of roosting bats found in, or near, a house is usually quickly exterminated.

Posted: September 20, 2015

Luckily for us and the bats, natural disasters and economic downturns have resulted in many buildings (e.g., large vacation houses, bars, barns) to be left completely abandoned throughout the island. We found that these structures now provide new and relatively conflict-free roosts for hundreds of bats in Grenada.

Walking into some of these houses felt sort of post-apocalyptic: lianas and other plants growing inside, bats hanging from the ceiling or flying around by the dozens, walls covered in guano, and floors covered in a thick layer of bat-dispersed seeds that were meant to grow in the forest.