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| Look at That Big Boy |
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We recently had to cut down three very tall Eucalyptus trees that Bob felt could cause a problem if for some reason they were to fall. He felt that in another year or two they might hit our house, car or fall on the pumping station next door. He hired a leņador (lumber jack) to drop the trees safely. It was an experience watching Chogo (nick name) cut down the trees. He could have driven a nail with them he was so accurate.
The last tree contained a surprise for when it dropped we could see a few bats flying out of the tree. Most of them (10 or so,) however, remained in their nest and Mary and I were horrified when the Costa Ricans poured gasoline on them and burned them up. When we finally waded through their explanation with our poor Spanish they explained that they were vampiros or vampire bats and they were very dangerous to their cattle.
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| Let me Taste Your Blood |
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I decided to do a bit of research and went to Mary's library and looked up vampire bats in a book titled "The Natural History of Costa Rican Mammals by Mark Wainwright," Following is a summary of some of the information I found.
Vampire bats are numerous and wide spread in most all tropical areas ranging from Texas, Florida and down to Argentina. They can be found from sea level to 8900 feet above and there are three species. The ones we found were the common vampire bat and they only drink blood. They occasionally take blood from poultry, wild mammals, people and other vertebrates, but their principal targets are livestock. They emerge during periods of little moonlight , flying silently about a meter off the ground usually following the course of a stream to the vicinity of their prey. The farther cattle herds are kept from such streams the lower the incidences of vampire bites.
Here is the spooky part. Once a common vampire bat has landed on or near its victim, it hops or crawls in a spider like fashion (using feet, wing thumbs and elbows)to a feeding spot. A heat sensitive nose helps it to detect veins beneath the prey's skin. It often selects areas with little hair, such as the feet, neck, ears, nipples, anus or vagina. Although the vampire has large canines, it's incisors are the most important feeding teeth. Having licked the bite site, the bat uses its lobed lower incisors to secure a firm hold of the skin, and its razor sharp upper incisors to shave away any fur and cut a shallow, roughly 5 by 8mm strip.
While vampires can inflict a deep and painful wound when biting in defense, intrepid biologists have reported that the feeding site is virtually painless. The bat laps rather than sucks at a feeding wound; grooves on the underside of the tongue draw in blood through capillary action. Vampires have anticoagulant in their saliva that keeps the blood flowing for up to 8 hours, but feeding seldom lasts more than 30 minutes. By this time the bat may have ingested more than half its body weight and be so bloated that it can barely fly. A feeding wound may be revisited on successive nights, sometimes by more than one bat.
Although they will pick any type of cattle they prefer certain breeds over others and on the rare occasions when they feed on people they seem to prefer certain individuals, often taking blood from some individuals while ignoring others nearby.
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| Bat Nest |
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Vampire bats roost in caves or other cavities and can have up to 2000 individuals in a colony but they usually contain less than 100. Ours had between ten and twenty. They usually only feed in a 5 Km range and always near livestock, preferably near streams. The danger to other mammals comes when livestock are removed from the area and they loose their food source. They may move the colony but in the meantime other mammals can become prey. In Nicaragua recently livestock were moved and the bats obtaining entry through poorly, and loosely built homes fed on children, generally selecting the big toe as the feeding site.
Vampire bats are dangerous as successive feedings can weaken the target animal and the wounds are susceptible to infection and occasion to diseases like rabies or hepatitis. Good screening in homes can prevent entry and eradication of the colonies eliminates the problem. Unfortunately, some farmers use gas, fire or powerful insecticides which kill good bats as well as the vampires as they many times nest together. A better method is to capture a vampire bat with a net, coat the captured bat with a sticky poison and then release it back into the colony. As vampire bats will groom and clean only their own, the poison will eliminate the vampire bats while leaving the other beneficial bats alive.
Although fruit bats and other species are important pollinators and insect eaters, so far I have been unable to find any beneficial qualities of the vampire bats, unless it is to reduce the mammal population in an area.
This may be a pretty spooky topic but other than the report from Nicaragua I have not heard of anyone being a victim of a vampire in our area. The farmers inspect their cattle regularly and treat the wounds with antibiotic creams. Anyway, we now know the reason for the Bat-B-Que and can understand the Tico animosity towards the Vampiros.
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| Bat-B-Que |
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