The vampire bats They are a group of flying mammals of the Chiroptera order belonging to the Phyllostomidae family and the Desmodontinae subfamily. They are very difficult animals to observe at night. Their presence is generally recognized by the fresh bleeding wounds they leave on their prey, before 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 leaf), present unique characteristics that clearly differentiate them from other species. Due to this, they are considered the most specialized group of bats and among the most exciting mammals of the Neotropics..
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 present a cosmopolitan distribution due to the introduction and breeding of livestock and farm birds throughout the continent. Like all bats, they have a mainly nocturnal activity.
These bats fly very low to follow the tracks of the mammals and birds on which they feed. 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.
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 does 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..
The tail is not developed, so they do not have an external tail like other bats.
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..
One of the most noticeable characteristics of these bats is the presence of highly developed thumbs on the forelimbs. These thumbs may have bearings in the case of the species Desmodus rotundus or be absent as in Diaemus youngi Y Diphylla ecaudata.
These pads allow them better support when it comes to moving in a quadruped way while approaching their prey..
The coloring of these bats is essentially brown. Only Diaemus youngi It has a more striking coloration due to its white wing tips.
Although the three species of vampire bats are similar to each other, they present differences that clearly delimit them within the Desmodontinae subfamily..
Diphylla ecaudata It is characterized by having very hairy hind legs, as well as a long and loose coat. In addition, it presents multilobed lower incisors forming two separate rows.
Desmodus rotundus has elongated thumbs in the forelimbs with the presence of three bearings that function as a support structure when they move along the ground.
On the other hand, Diaemus youngi It is distinguished by the presence of thick thumbs without bearings and also has white wing tips, a feature that the other two species of vampire lack, whose fur is predominantly brown.
These bats are highly specialized in terms of their 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 species Diaemus youngi Y Diphylla ecaudata they only feed on the blood of birds.
These bats, when locating their prey and the key sites to make a bite thanks to their thermoreceptors, make a small wound 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 the blood by continually licking the bleeding wound until they feel 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 be able to take the flight back to the colony..
Unlike many species of the Phyllostomidae family, Desmodontinae possess specialized organs for thermoreception in the nasal region. This allows them to effectively detect the points with the highest blood flow in the prey and the specific sites to make a small bite and allow blood flow..
In general, vampire bats visit only one animal, be it a terrestrial 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 source of food for species that consume mammalian blood or that in the absence of other resources can do so..
A common vampire bat (Desmodus rotundus) you can ingest 50-60% of your 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..
This species has been widely favored due to the great abundance of prey they currently have. Most of its current prey are 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..
It is a fairly rare species despite the fact that it has a wide distribution. Their 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 way 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.
It is also a rare species that feeds exclusively on the blood of birds. Like D. youngi flies at medium level over the forest in search of solitary birds in their refuges.
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 in the stomachs of these bats has been reported. It is likely that under certain food shortage circumstances, these bats will be able to use alternative food sources such as man.
Species of the Desmodontinae subfamily can be gregarious with a polygynous reproductive system or settle in monogamous pairs in small family groups..
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. Several of these groups can be established in a colony without coming into conflict with each other..
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.
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 of more than 50 individuals have been recorded. Some populations can reproduce throughout the year if resources are stable.
In captivity, it has been determined that they 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. Females continually participate in grooming activities, elimination of ectoparasites, and support for 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 to death 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..
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 odor 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.
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..
They live in a great diversity of forest and jungle environments. The wooded vegetation can be sparse or dense, they 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 is the case with the species. Desmodus rotundus.
The latter tolerate living near areas intervened for agricultural activities. Despite this, they prefer to stay away from human facilities.
Species like Diphylla ecaudata Y Diaemus youngi They 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 replace altitudinally Diaemus youngi.
When searching for prey, all species of vampire bats do so primarily in open areas with little vegetation..
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 they 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..
Due to the wide distribution of vampire bats, all three species are in the category of Least Concern according to the IUCN.
Although species like Diaemus youngi Y Diphylla ecaudata they are little recorded and are considered rare in nature, they have been reported in several localities that cover a large geographical area.
Both species are often confused with Desmodus rotundus and are selectively eliminated for fear that they can 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..