Vampire Bats In Belize: What's The Truth?

Bats are the only mammals with the ability to fly, and they make up about 58% of the mammal population in Belize. There are over 75 species of bats in Belize, including the Common Vampire Bat and the Hairy-Legged Vampire Bat. Vampire bats are fascinating creatures that feed on blood and have evolved with infrared sensors in their noses to detect heat and locate veins. With a rich biodiversity, Belize is home to a diverse range of bat species, contributing to the country's ecological balance.

Vampire bats are the only bats that feed on blood

Vampire bats are the only mammals that feed exclusively on blood. There are three known species of vampire bats: the common vampire bat (Desmodus rotundus), the hairy-legged vampire bat (Diphylla ecaudata), and the white-winged vampire bat (Diaemus youngi). These bats are found in Central and South America, and feed on the blood of other animals, a dietary trait called hematophagy.

Vampire bats have several adaptations that make them well-suited for feeding on blood. They have short, conical muzzles and lack a nose leaf, instead having naked pads with U-shaped grooves at the tip. The common vampire bat also has specialized thermoreceptors on its nose that help it locate areas where blood flows close to the skin of its prey. Vampire bats have front teeth that are specialized for cutting, and their back teeth are much smaller than those of other bats. They also have a high level of resistance to a group of bloodborne viruses known as endogenous retroviruses.

The feeding behaviour of vampire bats is fascinating. They typically feed at night, landing on the ground near their prey and approaching on all fours. They use thermoception to identify a warm spot on the skin to bite, then create a small incision with their sharp incisors. They lap up the blood from the wound, mixing it with their saliva, which contains anticoagulants and other compounds that prevent the blood from coagulating too quickly. A typical female vampire bat can consume over 20 grams of blood in a 20-minute feed.

Vampire bats have a strong sense of sociability. They form strong bonds with other members of their colony and often share food with hungry roost mates by regurgitating blood. This reciprocal behaviour is crucial for survival, as vampire bats can only survive a few days without feeding. Their social structure is based on female groups and their offspring, a few adult males known as "resident males", and a separate group of "nonresident males".

Vampire bats are small, weighing only about 40 grams, but their diet of blood poses several challenges. Blood is nutrient-poor, so vampire bats must drink up to 1.4 times their body weight in blood at each meal to get enough nutrients. This large volume of liquid can overwhelm their kidneys and bladder, and the high iron content can lead to iron poisoning. However, recent genetic studies have shown that vampire bats have lost certain key genes over their evolution that help them cope with this unique diet.

There are two species of vampire bats in Belize

The Common Vampire Bat (Desmodus rotundus) is the most widespread of the three vampire bat species, making up about 99% of the entire vampire bat population. It feeds on livestock and can be an agricultural pest. The Hairy-Legged Vampire Bat (Diphylla ecaudata), on the other hand, is a rare species that feeds only on large birds.

Vampire bats are members of the New World Leaf-nosed bats and are native to South and Central America. They are small in size, weighing only about 40 grams, with adult wingspans of 320 to 350 mm. Despite their small size, vampire bats have highly specialised adaptations for feeding on blood. For example, they have infrared sensors on their noses to detect heat and locate blood vessels close to the skin. They also have razor-sharp teeth without enamel, a grooved tongue for drawing blood, and saliva with anticoagulant properties to prevent blood clotting.

In Belize, bats make up about 58% of the mammal population. They play an important ecological role, contributing to pollination, seed dispersal, and pest control. While they may be feared and misunderstood, vampire bats are fascinating creatures that have evolved complex adaptations for survival.

Vampire bats have infrared sensors in their noses

Vampire bats are native to South and Central America, and Belize is no exception. In fact, the common vampire bat, or Desmodus rotundus, is classified within the same family as New World Leaf-nosed bats. Vampire bats are the only known mammals whose entire nutrition relies on blood from other mammals or birds.

Vampire bats have a unique ability to sense infrared radiation, which they use to locate blood-rich areas on their prey. This is made possible by infrared-sensitive receptors on their nose-leaf, which allow them to detect the infrared thermal radiation emitted by warm-blooded vertebrates. The pits on their noses are about 1 millimeter wide and 1 millimeter deep, hairless, and glandless, with a layer of dense connective tissue and sparsely distributed blood vessels providing insulation.

The infrared-sensitive receptors on the vampire bat's nose-leaf are highly specialized for sensing heat. They are capable of detecting power densities greater than 50 μW/cm2 at distances between 13 and 16 cm. This sensitivity is due to changes in the receptor's structure, which allow it to detect much lower levels of heat, around 86 degrees Fahrenheit (30 degrees Celsius) from about 8 inches (20 centimeters) away. In comparison, human heat sensors are typically tripped at around 110 degrees Fahrenheit (43 degrees Celsius).

The ability to sense infrared radiation is not unique to vampire bats, as some snakes and other vertebrates also possess this capability. However, the extreme low-temperature sensitivity of the vampire bat's receptors suggests specialization for sensing infrared thermal radiation. This adaptation allows them to locate blood vessels under the skin of their prey, ensuring they get their fill of blood without waking their sleeping victims.

In addition to their infrared-sensing abilities, vampire bats have other specialized traits that make them adept hunters. They have razor-sharp teeth for making precise cuts in the skin, and their agile nature allows them to move stealthily on the ground. They also have brain cells that are sensitive to the deep breathing sounds of sleeping animals, helping them identify potential prey.

Vampire bats have razor-sharp teeth and tongues that draw blood

Vampire bats are the only mammals that feed entirely on blood. They sleep during the day in total darkness, hanging upside down from the roofs of caves. They emerge during the darkest part of the night to hunt.

Vampire bats have very few teeth because of their liquid diet, but those they do have are razor-sharp. They have front teeth that are specialised for cutting, and their back teeth are much smaller than those of other bats. Their incisors are extremely sharp and lack enamel, which keeps them permanently sharp. Their canine teeth are also sharp and are used, along with their cheek teeth, to cut through hair.

Once they have located a sleeping animal, vampire bats land on the ground nearby and approach on all fours. They use a heat sensor on their nose to locate a spot where warm blood is flowing close to the skin. They then use their incisors to make a small incision, around 5-8mm deep and wide, being careful not to cut any arteries or veins.

The bat then uses its tongue to lap up the blood from the wound, while its saliva, which contains anticoagulants, prevents the blood from clotting and promotes continued bleeding. Vampire bats feed for around 20 minutes, adding almost 20-30% to their body weight in blood. They then return to their roost to spend the rest of the night digesting their meal.

Vampire bats' saliva contains anticoagulants to promote bleeding

Vampire bats are hematophagous, feeding on the blood of their prey. Their saliva contains anticoagulants that inhibit the coagulation factors IX (IXa) and X (Xa) in the blood of their victims, preventing it from clotting while they feed. This process is driven by a glycoprotein called draculin, which is a single-chain polypeptide protein composed of 708 amino acids.

Draculin is an anticoagulant that inhibits the conversion of prothrombin to thrombin, preventing fibrinogen from converting to fibrin. This process inhibits blood coagulation, keeping the blood of the bitten victim flowing. The activation of factor X is a common point between the intrinsic and extrinsic pathways of blood coagulation. Activated factor X (FXa) is the sole enzyme that catalyses the conversion of prothrombin into thrombin, which is vital in the coagulation cascade.

The saliva of vampire bats also contains fibrinolytic enzymes that prevent blood clotting during ingestion and digestion. The anticoagulant effect of the bat's saliva is intense and persistent, causing "residual haemorrhaging" in the prey. The anticoagulant effect can be observed by mixing the saliva with blood in vitro. Vampire bats also produce defensive bites, which are swift and produce wounds and bleeding, although these wounds are smaller than those produced by feeding bites.

The anticoagulant properties of vampire bat saliva have been observed to cause prolonged bleeding in prey, lasting hours after the bat has finished feeding. This is due to the persistent effect of the salivary anticoagulants. The anticoagulants in the saliva of vampire bats are large molecules (proteins) that can behave as antigens. This suggests that the prey of vampire bats may develop an immune response to the anticoagulants, as has been observed in other host-parasite systems between mammals and ticks.

The development of an immune response in prey could be detrimental to vampire bats, as it may result in difficulties in ingestion and digestion due to premature coagulation of blood. This could be dangerous for vampire bats due to their inability to withstand prolonged deficiencies in nourishment.

Frequently asked questions