What are bats?
Bats are the only mammals with the ability to fly effectively. The elongation of its fingers and the development of a membrane between them ease its invasion of airspace. Some of them develop membranes between the hind legs that ease capturing their food (insects). Because of the shape of their knees, bats are unable to stand on their feet. Hind legs have small claws that allow them to hang from the ceiling. This is why it is more common to see them hanging or in a horizontal position.

How do bats reproduce?
Bats are viviparous, which means that they give birth to their offspring in the stage when fetuses are well-developed. This usually occurs between one and three times a year depending on the species and age of the mother. Usually only one or two offspring are born per litter although in some species they can reach four per litter. In the last case, only one litter is born per year.

Offspring nurse since birth and remain attached to the mother`s body for a period of three to five weeks. At night, the mother usually places the offspring in a specific location of the daytime refuge (cave, house, tree, etc.) and goes out to feed itself. Upon return, the mother recognizes her offspring by the smell and by specific calls they learn from their mother. After several weeks, the offspring learns to fly and goes out for food with its mother until it reaches adulthood when it can fend for itself.

Are bats blind?
NO, they have functional eyes with which they see silhouettes and perceive changes in the intensity of light. Unlike other mammals, they have relegated smell and vision as alternate means of guidance. Instead, they emit sound waves to become oriented. These waves emitted in the larynx, collide with objects and reflect as echoes which are captured by the ear and interpreted by the brain. Through this mechanism, they can tell distance, orientation, and shape of the object. This guidance is known as echolocation and is particular to bats, whales, and only one species of birds.

Are there vampire bats in Puerto Rico?
NO, although there are other countries in South America and Mexico where there are bats that feed on blood, this is not the case on the island. The species that exist here feed on insects, fruits, leaves, pollen, and fish. Depending on the species, they concentrate on one or more food items. Some eat insects exclusively and others eat fruit. The rest alternate between fruit and pollen, fruit and insects, insects and fish. Vampires or bats that practice hematophagy do not suck blood as the legend says. These approach their victims by crawling on the ground. They make a small wound from where they lick the blood. They usually attack cattle by the legs.

Are bats dangerous?
YES, careless handling of bats can produce a very painful wound. Although there are small bats in Puerto Rico that cannot cause any damage with their bite, larger ones may be somewhat more dangerous. The presence of rabies in bats has proven to be minimal (.5%). However, any kind of contact with them should be avoided. Contrary to popular belief, bats do not get tangled up in people`s hair. In the few cases where this has been reported, it was caused by the bat`s miscalculation while flying in search of a mosquito —which normally flies over our heads. This has been exaggerated in terms of the number of incidents. Even if a bat would run into us, it would fall to the ground, as it is not easy for them to get caught on our clothing. Bats are not aggressive and they respond to caresses like any other animal.

There is a stage in which bats can be a danger to our health. The presence of pathogenic fungi in bats and their relationship to the caves indicate that the entire cave that contains bats can be a potential source of infection of several diseases. The histoplasmosis or illness of the caves is one of the best known ones. It is acquired by inhaling from the air spores of the fungus that causes the disease. In most cases it is not fatal but it can produce lesions in the lungs, liver and spleen, and even death. Anyone who visits a cave should take precautions before entering and must be informed in advance about possible dangers.

On the other hand, bats that inhabit houses sometimes cause health problems to those who live there. The droppings of bats that live in houses are dusty as they consist of dead insects. This dust slips between the cracks causing allergies and breathing problems. This along with urine can contaminate food.

Where do bats live?
In Puerto Rico, bats use caves, tunnels, ceilings, palm tree fronds, palms and hollow trees as a place of daytime refuge. Their habitat is the airspace where they look for food. Some species are very selective as to the place they use to sleep, while others are not. In Puerto Rico, only one species uses houses as a daytime refuge.

Why are bats so important?
The benefits bats bring to the ecosystem and human kind far exceed all the negative aspects attributed to them. Insect control, pollination of many plants, and seed dispersal are several of their contributions. A bat can consume up to ⅓ of its weight in insects in one night. If you add the millions of bats that exist, this figure reaches thousands of tons per year in insect control, many of them harmful to agriculture. The pollination of bananas, plantains, and papaya, among other fruits of commercial importance is due to bats. They also spread tree seeds in our forests which help conserve natural vegetation. Bats contribute to the creation of energy in cave ecosystems. Without this contribution caves would be scarce in fauna and this system would become impoverished.

How can we avoid the disappearance of bats?
We must always avoid disturbing bats found in caves. Some of those are offspring whose energy consumption increases if we bother them or make them fly while they are resting. We must preserve the caves and habitat so that these may reproduce and continue their natural contribution to the ecosystem. In the case of bats that live in houses, they should be displaced from the roofs and not killed. The use of pesticides for pest control should also be reduced. Pesticides reach bats when they eat contaminated insects. In the future, that can be the most imminent danger to bats.

List of bats from Puerto Rico

  1. Name: Noctilio leporinus mastivus
    Fish and insects
    Daytime refuge: caves and hollow trees
  2. Name: Pterenotus quadridens fuliginosus
    They feed on:insects
    Daytime refuge: caves
  3. Name: Pteronotus parnelli portoricensis
    They feed on:insects
    Daytime refuge: caves
  4. Name: Mormoops blainvilli cinnamomeum
    They feed on: insects
    Daytime refuge: caves
  5. Name: Artbeus jamaicensis jamaicensis
    They feed on: fruits, leaves
    Daytime refuge: caves, hollow trees and groves
  6. Name: Stenoderma rufum darioi
    They feed on: fruits
    Daytime refuge: groves
  7. Name: Eptesicus fuscus wetmorei
    They feed on: insects
    Daytime refuge: caves and groves
  8. Name: Lasiurus boreal Minor
    They feed on: insects
    Daytime refuge: groves
  9. Name: Tadarida brasilienis antillularum
    They feed on: insects
    Daytime refuge: caves
  10. Name: Molossus molossus fortis
    They feed on: insects
    Daytime refuge: houses and palm fronds
  11. Name: Brachyphylla cavernarum intermedia
    They feed on: insects and fruits
    Daytime refuge: caves
  12. Name: Erophylla sezekorni bombifrons
    They feed on: fruits and pollen
    Daytime refuge: caves
  13. Name: Monophyllus redmani portoricensis
    They feed on: pollen
    Daytime refuge: caves


Author: Grupo Editorial EPRL
August 27, 2014.

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