VAMPIRE BAT: CHARACTERISTICS, FEEDING, REPRODUCTION, BEHAVIOR - BIOLOGY - 2025

The vampire bats are a group of flying mammals of the order Chiroptera belonging to the subfamily Desmodontinae Phyllostomidae and family. They are very difficult animals to observe at night. Their presence is generally recognized by the fresh bleeding wounds they leave on their prey; in the event of any disturbance they fly quickly to flee from any threat.

The Desmodontinae subfamily, in contrast to the rest of the subfamilies included in the Phyllostomidae family (bats with nasal leaves), present unique characteristics that clearly differentiate them from other species. Because of this, they are considered the most specialized group of bats and among the most exciting mammals in the Neotropics.

Common vampire bat (Desmodus rotundus)

perching Acatenazzi at English Wikipedia / CC BY-SA (http://creativecommons.org/licenses/by-sa/3.0/)

On the other hand, vampire bats have low species richness. The subfamily is made up of only three species, all typical of the American continent. They have a cosmopolitan distribution due to the introduction and rearing of livestock and farm birds throughout the continent. Like all bats, they are mainly nocturnal.

These bats fly very low to follow the tracks of the mammals and birds they feed on. To be captured, it is necessary to place the fog nets at ground level since these bats in addition to flying very well also move efficiently on the ground thanks to adaptations in the thumbs.

General characteristics

Head

The bats of this subfamily are characterized by having a very short face and a very high and voluminous skull. The face has two wide or narrow folds on the rinary and they do not develop a true nasal leaf like the rest of the subfamilies of the Phyllostomidae family.

In the nose there is a fold with three holes or cavities that are responsible for the detection of thermal stimuli. Tests have determined that vampire bats can detect warm-blooded animals at distances greater than 16 cm.

The lower lip of the mouth has special adaptations, presenting a channel or slit in the middle. They have relatively large eyes, the ears are medium, wide and directed forward, almost forming a kind of funnel.

Tail

The tail is not developed, so they do not have an external tail like other bats.

Dentition

At the level of the teeth they present great modifications. The central incisors are close together and are longer than the canines. In addition to this, the incisor teeth are very sharp, which allows them to make small cuts in the skin of the animals on which they feed.

On the other hand, all molariform teeth are reduced as an adaptation to their highly specialized liquid diet. The lower jaw is characterized by the presence of a diastema or space between the incisors through which vampire bats stick out their long tongue to lick up the blood and allow a continuous flow into the mouth.

Skull and dentition of Desmodus rotundus

Batfossil / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Thumbs

One of the most noticeable characteristics of these bats is the presence of highly developed thumbs on the forelimbs. These thumbs may be bearing in the case of Desmodus rotundus or absent as in Diaemus youngi and Diphylla ecaudata.

These pads allow them better support when it comes to moving in a quadruped way while approaching their prey.

Coloration

The coloring of these bats is essentially brown. Only Diaemus youngi has a more striking coloration due to its white wing tips.

Taxonomy and classification

Taxonomy

Although the three species of vampire bats are similar to each other, they present differences that clearly delimit them within the Desmodontinae subfamily.

Species:

Feeding

These bats are highly specialized in diet and differ significantly in this regard from the other species of the Phyllostomidae family, which are mainly frugivorous.

The three species found in this subfamily feed exclusively on blood. Desmodus rotundus feeds only on mammalian blood while the species Diaemus youngi and Diphylla ecaudata only feed on bird blood.

Desmodus rotundus in feeding activities

Sandstein / CC BY (https://creativecommons.org/licenses/by/3.0)

These bats, when locating their prey and the key sites to make a bite thanks to their thermoreceptors, make a small wound of about 4mm wide and 5mm deep through their incisor teeth.

Once they bite, the blood begins to flow freely thanks to anticoagulant compounds present in the saliva of these bats.

Blood-sucking bats ingest blood by continually licking the bleeding wound until they are completely satiated or are driven away by some disturbance. Once they have full stomachs, it is generally difficult for them to fly again, retreating from prey with quadruped locomotion.

Blood is rapidly processed in the stomach and the watery portion is eliminated in the urine to lose weight and take the flight back to the colony.

Dams

Unlike many species of the Phyllostomidae family, the Desmodontinae have specialized organs for thermoreception in the nasal region. This allows them to effectively detect the points with the highest blood flow on the dams and the specific sites to make a small bite and allow blood flow.

In general, vampire bats visit only one animal, be it a land mammal or a bird, per night, but it is possible that they visit the same individual several consecutive nights.

Prey includes a great diversity of wild mammals and birds, however the introduction of farmed animals has increased the amount of food resources. Man is also a food source for species that consume mammalian blood or that in the absence of other resources can do so.

A common vampire bat (Desmodus rotundus) can ingest 50-60% of its body weight in blood each night. Sometimes, due to the presence of anticoagulants in the bat's saliva, they can cause an animal to lose large volumes of blood, which generates a decline in physical condition.

Desmodus rotundus

This species has been widely favored due to the great abundance of prey they currently have. Most of its current prey is represented by a variety of livestock such as cattle, horses, pigs and goats.

The introduction of these species of mammals is considered the most important factor for the expansion of the populations of these bats in America. Many populations of these bats prefer to consume cattle blood than the blood of wild mammals, which is because cattle are more predictable prey.

Diaemus youngi

It is a fairly rare species despite the fact that it has a wide distribution. Your activity schedule begins well into the night. As some authors have pointed out, several family groups can search for food together.

They fly low and medium height among the trees looking for solitary birds on branches to feed. Once they detect a prey, they perch near it and move in a quadruped manner until they position themselves under the bird.

This species invariably bites areas near the cloaca without causing any disturbance to the bird. However, if its presence is noticed by the bird, the bat remains immobile so as not to be located and potentially injured. In captivity, these bats are unable to feed on mammalian blood.

White-winged vampire bat (Diaemus youngi)

The original uploader was Gcarter2 at English Wikipedia. / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.5)

Diphylla ecaudata

It is also a rare species that feeds exclusively on the blood of birds. Like D. youngi it flies at medium level over the forest in search of solitary birds in their shelters.

These bats are frequently observed feeding on poultry (chickens, turkeys, among others) within their foraging area.

It has also been recorded that these bats try not to feed on the same bird two consecutive nights so as not to negatively affect them.

In some localities the presence of human blood has been reported in the stomachs of these bats. It is likely that under certain food shortage circumstances, these bats will be able to use alternative food sources such as man.

Reproduction

Species of the Desmodontinae subfamily can be gregarious with a polygynous reproductive system or settle in monogamous pairs in small family groups.

Desmodus rotundus

It reproduces throughout the year. An adult female can have two or three young in a single year. They are usually gregarious. The males form harems, forming a compact group consisting of one male and between 4 and 12 females and their young. In a colony several of these groups can be established without coming into conflict with each other.

Diaemus youngi

This species establishes monogamous relationships with a single female and forms a family group consisting of a male, a female and their young.

Several family groups can use the same refuge, establishing aggregations of up to 30 individuals, but each group is spatially separated from neighboring groups. This species does not reproduce throughout the year but reproductive events occur in the dry season.

Diphylla ecaudata

It has a reproductive behavior similar to that of D. youngi, however, this species generally lives in caves without mixing with the colonies of other species and establishing strong ties with other members or family groups of the colony.

Generally the groups of this species do not exceed 12 individuals. In few cases, colonies greater than 50 individuals have been recorded. Some populations can reproduce throughout the year if resources are stable.

Behavior

Behavior of

In captivity, they have been found to establish complex dominance hierarchies, with the male of the harem being the most dominant.

The females of the reproductive group establish very close bonds with each other and with their young, while the males are not as social. The females participate continuously in grooming activities, elimination of ectoparasites and support in disputes with other groups.

These bats are the most aggressive of the blood-sucking bats. When captured, they generally emit a series of high-pitched screeches and continually seek to bite their captor. They are quite elusive, when detected they take flight quickly.

It is common for group members to share part of the food eaten after feeding activities, either with other females or with their young. A female usually regurgitates part of the stomach contents and this is ingested by a young or a closely related female.

In addition to this, it has been observed that females can share blood with related bats that failed to eat. A blood-sucking bat starves if it goes 48 to 72 hours without ingesting blood. In this way, sharing part of the intake between related individuals results in a survival strategy.

Behavior of

When this species is captured and feels threatened, they open their mouths and emit a short, high-pitched screech. After this it projects the salivary glands and they launch a kind of very fine aerosol of a penetrating liquid with an almond smell that is repugnant to its captors.

This species is also capable of making precise and specific antiphonal sounds for the recognition of its congeners once they return to the colony.

Behavior of

This species has a more docile behavior than that of D. youngi, however, it does not show the salivary glands or launch any defensive aerosol. It also emits vocalizations when arriving at the colony to determine the location of its congeners.

Habitat and distribution

Habitat

They live in a great diversity of forest and jungle environments. Wooded vegetation can be sparse or dense, can occupy low forests and ecotone formations between forests and savanna areas.

They can also occupy forest clearings and hot areas at sea level up to altitudes close to 3000 meters of elevation with low temperatures.

They take refuge during the day in natural caves, tree holes and can even settle in human constructions such as cavities under bridges or abandoned human buildings, as in the case of the Desmodus rotundus species.

The latter tolerate living near areas intervened for agricultural activities. Despite this, they prefer to stay away from human facilities.

Species such as Diphylla ecaudata and Diaemus youngi prefer less intervened habitats, especially deep galleries in caves without mixing with other species or in caves and tree trunks respectively. Both species are ecologically similar, however, D. ecaudata seems to substitute altitude for Diaemus youngi.

When searching for prey, all species of vampire bats do so primarily in open areas with little vegetation.

Distribution

Generalized distribution of the Desmodontinae A proietti subfamily / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

The three species belonging to the Desmodontinae subfamily have a wide distribution in the Neotropics and are a frequent finding in many localities.

Vampire bats have a distribution from Mexico through much of Central America to northern Argentina including the Amazon rainforest, the Guiana shield and other bioregions.

Species like D. ecaudata have an equally wide distribution but it is absent in the central Amazon basin. Wandering individuals have even been reported in the United States.

Of the species in the Desmodontinae subfamily, the one with the widest distribution is by far D. rotundus. There are recorded populations from northern Mexico to northern Argentina, including populations on the island of Trinidad and Tobago and the island of Margarita in Venezuela.

The caves or roosting places that this species occupies generally have a strong ammonia odor from the digested blood that has accumulated on the ground.

State of conservation

Due to the wide distribution of vampire bats, all three species are in the category of Least Concern according to the IUCN.

Although species such as Diaemus youngi and Diphylla ecaudata are little recorded and are considered rare in nature, they have been reported in several locations that cover a large geographic area.

Both species are often confused with Desmodus rotundus and are selectively eliminated for fear that they may transmit diseases such as rabies and generate large economic losses such as those caused by the common vampire bat D rotundus.

Many colonies of D. rotundus are constantly eliminated to avoid economic losses due to the transmission of diseases such as rabies.

Many populations of vampire bats have been diminished or completely eliminated through poisoning, through the use of systemic anticoagulants applied to livestock. Once a poisoned bat shares blood with other congeneric bats, they are also poisoned.

References

1. Acha, PN, & Málaga-Alba, M. (1988). Economic losses due to Desmodus rotundus. Natural history of vampire bats, 207-214.
2. Aguiar, LMDS, Camargo, WRD, & Portella, ADS (2006). Occurrence of white-winged vampire bat, Diaemus youngi (Mammalia, Chiroptera), in the Cerrado of Distrito Federal, Brazil. Revista Brasileira de Zoologia, 23 (3), 893-896.
3. Barquez, R., Perez, S., Miller, B. & Diaz, M. 2015. Desmodus rotundus. The IUCN Red List of Threatened Species 2015: e.T6510A21979045. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T6510A21979045.en. Downloaded on 03 March 2020.
4. Barquez, R., Perez, S., Miller, B. & Diaz, M. 2015. Diaemus youngi. The IUCN Red List of Threatened Species 2015: e.T6520A21982777. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T6520A21982777.en. Downloaded on 03 March 2020.
5. Carter, GG, Fenton, MB, & Faure, PA (2009). White-winged vampire bats (Diaemus youngi) exchange contact calls. Canadian Journal of Zoology, 87 (7), 604-608.
6. Castro, FFC (2016). New report of the hairy-footed hematophagous bat Diphylla ecaudata Spix, 1823 (Chiroptera, Phyllostomidae) in Colombia. Neotropical Mastozoology, 23 (2), 529-532.
7. Delpietro, HA, & Russo, RG (2002). Observations of the common vampire bat (Desmodus rotundus) and the hairy-legged vampire bat (Diphylla ecaudata) in captivity. Mammalian Biology, 67 (2), 65-78.
8. Denault, LK, & McFarlane, DA (1995). Reciprocal altruism between male vampire bats, Desmodus rotundus. Animal Behavior, 49 (3), 855-856.
9. Elizalde-Arellano, C., López-Vidal, JC, Arroyo-Cabrales, J., Medellín, RA, & Laundré, JW (2007). Food sharing behavior in the hairy-legged vampire bat Diphylla ecaudata. Acta Chiropterologica, 9 (1), 314-319.
10. Greenhall, AM (1970). The use of a precipitin test to determine host preferences of the vampire bats, Desmodus rotundus and Diaemus youngi. Bijdragen tot de Dierkunde, 40 (1), 36-39.
11. Ito, F., Bernard, E., & Torres, RA (2016). What is for dinner? First report of human blood in the diet of the hairy-legged vampire bat Diphylla ecaudata. Acta Chiropterologica, 18 (2), 509-515.
12. Kürten, L., & Schmidt, U. (1982). Thermoperception in the common vampire bat (Desmodus rotundus). Journal of comparative physiology, 146 (2), 223-228.
13. Sampaio, E., Lim, B. & Peters, S. 2016. Diphylla ecaudata. The IUCN Red List of Threatened Species 2016: e.T6628A22040157. https://dx.doi.org/10.2305/IUCN.UK.2016-2.RLTS.T6628A22040157.en. Downloaded on 03 March 2020
14. Sétien, AA, Brochier, B., Tordo, N., De Paz, O., Desmettre, P., Péharpré, D., & Pastoret, PP (1998). Experimental rabies infection and oral vaccination in vampire bats (Desmodus rotundus). Vaccine, 16 (11-12), 1122-1126.
15. Voigt, CC, & Kelm, DH (2006). Host preference of the common vampire bat (Desmodus rotundus; Chiroptera) assessed by stable isotopes. Journal of Mammalogy, 87 (1), 1-6.
16. Wilkinson, GS (1986). Social grooming in the common vampire bat, Desmodus rotundus. Animal Behavior, 34 (6), 1880-1889.
17. Wimsatt, WA (1969). Transient behavior, nocturnal activity patterns, and feeding efficiency of vampire bats (Desmodus rotundus) under natural conditions. Journal of Mammalogy, 50 (2), 233-244.