Vampire Bats

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Vampire Bats

There are 3 different species of vampire bats that inhabit parts of Costa Rica. They are: the common vampire bat, the hairy-legged vampire bat, and the white-winged vampire bat. The flattened faces and M-shaped noseleaves of true vampires do not resemble those of any other bats. Within the three-species, the hairy-legged vampire bat can be recognized by its short, broad ears, large eyes, and heavily-haired legs, while the white-winged vampire bat can obviously be distinguished by its white-tipped wings, as the common vampire bat possess pale-tipped wings. Other distinguishing features include tail membrane and thumb designs.

These three species of bats are the only bats in the world that drink blood. Common vampire bats sporadically take blood from poultry, wild mammals, people, or other vertebrates, but their staple blood source appears to be livestock. They feed mainly during periods of little moonlight, and clandestinely fly only a few feet off the ground, normally following the route of a stream or river to the area of their prey. Once the prey is located, the common vampire bat crawls by using its feet, wing thumbs, and elbows to the preferred feeding spot. More often than not, the common vampire bat will pick a hairless location, such as the feet, neck, ears, nipples, anus, or vagina. Although the vampire bat has impressive canine teeth, it’s the incisors that are the bats most important feeding teeth. Having licked the bite site, the bat then uses its razor sharp incisors to shave away any remaining fur and cut out a small strip to secure a firm hold on the skin of its prey. Vampire bats are capable of inflicting a painful bite when becoming defensive but while feeding the bite is literally painless. The vampire bat seldom feeds for more the 30 minutes, since by that time it has consumed more than half its body weight and can become so bloated it will barely be able to fly. A feeding site may be revisited on consecutive nights, and frequently by more than one bat.

It has been observed that vampires can prefer certain types of cattle, and on the rare occasion that they feed on humans, vampires seem to prefer certain individuals, frequently taking blood from the same person on successive nights while disregarding others nearby.

Common vampires roost in caves and other cavities in groups or colonies that can have upwards of 2,000 individuals, but normally the number is less than 100. When disturbed they tend to scurry into crevices rather than fly away. In roosts, vampires gather into clusters usually containing a harem of about 8 to 20 females and young, which are protected by a single male. Males will fight ferociously to gain access to harems. Harems stick together for extended periods of time and form strong ties to one another, sharing feeding sites and regurgitating blood to one another.

Common vampire bats breed at any time of year possibly due to the abundance of their food source. A female produces only one pup each year and although young can forage for blood from the age of four months, they are extremely slow to become independent, taking as long as 10 months.

The white-winged vampire bat will sometimes feed on livestock but seem to prefer mammal blood. They will approach a roosting bird by crawling along the underside of a branch or limb and lick a bite area for a few moments; bite area meaning either the feet or the anus. If not detected by the bird, the white-winged vampire will feed for approximately 15 minutes, often draining its victim to death. They feed on a wide variety of birds weighing anywhere from ½ ounce to 7 ounces, but don’t appear to be interested in smaller prey, such as hummingbirds.

The white-winged vampire roosts in caves and hollow trees in clusters of up to 30. The males appear to establish hierarchies through a bizarre fashion of threat displays including rising up on their feet and thumbs, boxing with their closed wings, hissing, and spraying one another with a musky secretion. Eventually one will submit.

The hairy-legged vampire bat only feeds on bird’s blood. It feeds on the feet or the anus of the bird. The roost in caves and hollow trees, normally singly, although several individuals may live in various regions of the same roost.

Concerns-

Common vampire bats leave wounds on livestock that are vulnerable to infection or worse a harbinger for rabies. The species is directly responsible for an estimated 100 million dollars in damage to livestock each year in Central and South America. Unfortunately, indiscriminate eradication has resulted in the destruction of numerous other bat species.