By Janet Tyburec
You dont have to be an intrepid biologist to observe bats in the wild. This is especially true in tropical areas, such as Latin America or the Caribbean islands, where it is unusual not to see bats at night as they chase insects at streetlamps and forage around fruiting and flowering trees. So if youre heading for the tropics, be sure to reserve cocktail hour to watch bats in flight, and take along the following tips for other bat-viewing opportunities.
1. Put a light on the subject.
Take along a powerful rechargeable light (such as a 500,000-candlepower blaster light). An occasional, rapid sweep of the light across trees, shrubs, and calm waters will often reveal bats in flight, especially in the first two hours after sunset.
2. Watch the sky.
At dusk, birds are returning to their roosts while bats are just emerging, so keep in mind that bat flight is erratic, but birds are usually direct, and bats seldom glide, while birds often do. To remove any doubt, we recommend investing in a bat detector, which translates echolocation calls into sounds audible to humans. Although fruit- and nectar-eating species may not be heard, most insect-eating bats that can be seen in the open will come through loud and clear.
3. Seek out still waters.
Many species of insect-eating bats forage low over calm parts of streams, rivers, and lakes. People quietly boating at dusk often report groups of fishing bats following along in their boats wake (over both freshwater and ocean). A quick scan with a spotlight will illuminate the bats. These bats are also sometimes easily observed as they fish under dock lights.
4. Look under leaves and eaves.
You can often spot foliage-roosting bats by simply walking around your resort grounds looking for what at first appear as shadows beneath large leaves. A careful peek may reveal bats, but dont approach too close, shine a powerful light on them, or touch nearby branches; the bats may fly away. A dim light, such as a headlamp, should be okay as long as you dont disturb the bats for more than a few seconds. If they appear nervous, step away.
Many tropical bats modify leaves to create weather-resistant tents, where they roost individually or in small harem groups. (See BATS, Spring 1994 feature on tent-making bats.) Heliconia, banana, and philodendron are common shelters, as are the leaves of fan palms and similar plants. Some bats also roost in dead palm fronds and by extension, in the thatched roofs common in tropical resorts. Any dark nook in a building could potentially be a bat hideaway, particularly under eaves or behind shutters. Even if the bats are not visible by day, telltale droppings or squeaking sounds may show you where to watch at dusk.
5. Keep an eye on flowers and hummingbird feeders.
Nectar-feeding bats visit flowers, often light-colored, that bloom at night. Flowering banana, kapok, or balsa trees are all bat favorites, with the largest sometimes attracting hundreds or thousands at a time. Bananas and many types of columnar cactus and agave plants open new flowers each night, beginning soon after sundown. By checking the size of buds during the day, you can learn to predict which buds will flower on any given night. All of these plants are frequently used as ornamentals at resorts and lodges, and if your stay coincides with a peak blooming period, you may enjoy great bat watching right outside your door. Also, lodges that install hummingbird feeders to attract birds by day may be inadvertently attracting bats at night. (Ask the manager to refill empty feeders in the late afternoon.)
6. Hang out around fruiting trees and shrubs.
Fruit-eating bats will visit a wide variety of fruit-producing plants found at resorts and parks. Just ask local residents to point out trees where they have seen bats before. Among the most typical are fig, sea almond, papaya, mango, and some palm fruits. (Most of these are found in tropical areas worldwide.) Large fig trees, often used as ornamentals, can attract literally thousands of bats when they are producing fruit. The sea almond, a common beach-side resort shade tree, appeals to large species of fruit bats that visit the trees yellowish-to-reddish fruits a few at a time.
7. Double-check that patch of lichen.
Sac-winged bats in Mexico, Central, and South America often roost right out in the open. Tiny proboscis bats can be found on the undersides of especially large tree trunks that lean out over forest-bordered lakes and rivers. These bats typically roost in groups of three to 20 or more and at first resemble lichen. Binoculars may be the best means to observe them, because they are easily disturbed and will leave if you approach too rapidly or closely. Other members of this family roost on tree trunks within the forest, especially in crevices or convolutions created by fig and strangler fig trees.
8. Roam the ruins.
Many bats, including free-tailed, sac-winged, leaf-nosed, and vampire bats, are commonly found in the dark vestibules and crevices of Aztec, Mayan, and other ruins, and can be seen with the aid of a headlamp. Often sac-winged bats can be identified by their roosting postures. Rather than forming clusters, they prefer to hang individually with wings folded but slightly spread, heads raised, and feet wide apart, making them look like tiny five-pointed stars. Please be careful not to frighten these bats or to attract the attention of other visitors who might harm them.
Sharing your interest in bats will encourage resort staff and local naturalists to become more aware and appreciative of these often-overlooked animals, but be careful to advocate only non-disruptive bat watching. Bats are easily disturbed, so it is best to simply observe from a distance with binoculars or as they emerge from their daytime homes. Entering bat caves, mines, tunnels, or other roosts on your own can be dangerous to both you and the bats. If disturbed too often, bats will likely abandon their roosts, forcing them to expend additional energy trying to survive in sub-standard places. A donation of a bat detector or useful publication to a favorite lodge or naturalist you meet on a trip would be a great way to promote responsible bat watching after you are gone.
Janet Tyburec is BCIs Education Programs Director.
Please note: Those planning to bat-watch in Central or South America may want to be prepared to respond to questions about vampire bats. Past BATS articles (including Vampires: The Real Story in Spring 1991, and Lure of the Vampires in Summer 1997) can be found in the BATS archive on the BCI web site at www.batcon.org/batsmag/batindex.html, or you can call BCI to request information.
For further reading:
Emmons, L.H. 1997. Neotropical Rainforest Mammals: A Field Guide. 2d ed. University of Chicago Press. 307 pages.
Reid, F.A. 1998. A Field Guide to the Mammals of Central America and Southeast Mexico. Oxford University Press. 400 pages.
Watching banana trees at night is one of the best ways to see bats all over the world. This common long-tongued bat (Glossophaga soricina
) is one of many Latin American species attracted to the new blooms a fruiting banana plant produces nightly.
These dwarf fruit bats (Artibeus phaeotis
) are roosting in a Heliconia leaf, the type of large, symmetrically shaped leaf typically chosen by tent-making bats. Bite marks down the midrib show how the bats make the leaf fold down in a tent-like form that is easy to spot.
As you approach, be careful not to make crackling sounds or to touch anything that will cause the roost to move. Once you have a good viewing angle under the leaf, you may need a dim light. Most bats are tolerant if you are quiet and still and dont shine too much light on them. If they appear restless, stop or back up.
Because their branches spread out in flat swirls like an umbrella, sea almond trees are grown for shade at most tropical beach resorts. You may be able to spot fruit-eating bats such as this Jamaican fruit bat (Artibeus jamaicensis
) around the tops of trees that have ripe yellowish-to-reddish fruits (each with an almond inside). The bats carry the fruits away one at a time to eat elsewhere.
Several tropical bat species, including this Jamaican fruit bat, feed on balsa flower nectar, serving as key pollinators. Visiting bats can be observed at most blooming balsa trees, especially with the use of a powerful light.
Nectar bats such as this Jamaican long-tongued bat (Monophyllus redmani
) are attracted to the night-blooming flowers of agaves, which sit on a tall spike protruding from the center of the plant, a low-lying, circular-shaped succulent with broad, spiked leaves.