From the 200 mammal species 100 are bats
Of the more than 200 Costa Rican Mammal species, 50% are bats. Many lowland open areas have small bats swooping around at dusk, catching insects. Larger bats eat fish, fruit, or small animals, and others drink flower nectar or animal blood.
During the day bat roost in hollow trees (local naturalist guides know where to look) or under wooden roofs. I saw several white-lined sac-winged bats (murciélago de saco; Saccopterynx bilineata) in buildings in the Santa Rosa National Park. These small social bats roost in colonies of 5 to 50 individuals and have dark fur with two long wavy white lines on the back.
One of the largest bats is the fishing bulldog bat (murciélago pescador; Noctillo leporinus), which has a 60cm wingspan. Most of this is skin and bones, so adults weigh under 90g - big as bats go. They fish in both salt and fresh water, and the Tortuguero canals are ideal for watching them grab large insects and small fish with their sharply clawed enlarged feet. You can tell them apart from other bats that are drinking by watching their feet dip into the water.
Another large bat, the Jamaican fruit bat (murciélago frutero; Artibeus jamaicensis), feeds on fruits of large trees, especially figs, which they grab on the wing and take to a feeding roost for consumption. They have 40cm wingspans and weigh 50g; there are several smaller species of fruit bat. These bats won't feed during the brightest full-moon nights for fear of owls.
All tree species of vampire bats (vampirus) are restricted to the Neotropics (not Transylvania!) and are found in Costa Rica, where the most common is Desmodus rotundus). Unusual among bats, vampires are agile on the ground and can hop, run and crawl toward their prey, which consists of birds and mammals, though cattle are preferred. Razor-sharp incisors make a small cut on the prey, and the flowing blood is licked up, not sucked. Anticoagulants in the bats' saliva ensure the blood flows freely during the meal. The process doesn't cause much harm to the cattle, but there is potential danger of bat-borne diseases, especially rabies, which kill the prey (but not the bat).
Because of local misconceptions that all bats are vampires they may be indiscriminately killed. However their usefulness in controlling insects and pollinating flowers far outweighs their potential damage.
Most people think of bats as being black, but a variety of browns, grays, yellows, and reds also exists. Two uncommon Costa Rica species are white: the tiny Honduran white bat (Ectophylla alba) of the Caribbean slopes, and the larger ghost bat (Diclidirus virgo) seen in the Peninsula de Osa.
Pictures by Angela and Jörn Malek. The team of Discovery Travel World wishes you the best of times in our little paradise called Costa Rica.
Text by Lonely Planet.