Greater Noctule bat
Encyclopedia
The Greater Noctule bat (Nyctalus lasiopterus) is a rare mammal found in Europe, West Asia, and North Africa. It is the largest and least studied bat in Europe with a wingspan of up to 46 centimeters and is one of the few bat species to feed on passerine birds. Greater Noctule bat is the only bat species to hunt birds on the wings rather than when roosting. Greater Noctule bat employs echolocation, has wings adapted for open-air hunting, and has echolocation frequencies above the hearing range of birds. These characteristics of Greater Noctule indicate that it is well adapted for hunting passerines in the air.
The wings of the Greater Noctule bat are thinner than those of birds which allow it to maneuver quickly and accurately. While its wing is delicate and rips easily, it is able to regrow. The Greater Noctule is one of the largest bats with a wingspan of up to 455 mm. Its total body length ranges from 152 to 162 mm and its forearm ranges from 62 to 68 mm. The Greater Noctule Bat has been observed as a high altitude flier and a low altitude forager. The dorsal fur of the Greater Noctule bat is uniformly reddish-brown to dark brown. Its muzzle is broad with enlarged short ears and its tragus is broad, short, and mushroom-shaped. Calcar, also known as calcaneum, is present and it reaches close to midway to the tail membrane.
The Greater Noctule bat has a robust skull and its rostrum
is square with an ordinary nasal
slit. The zygomatic
arches are very slender and the braincase is smooth, turned upwards. The sagittal crest
is not present, while the lambdoid crest is well developed. Most of the projecting point of the skull is made up of exoccipital condyles. The basisphenoid is wide and deep and the tympanic bullae are relatively small.
The Greater Noctule bat is a rare mammal in the order Chiroptera. It belongs to the family Vespertilionidae (vesper bats) and to the genus “Nyctalus” (noctule bats). Out of two traditionally recognized suborders Megachiroptera (megabats) and Microchiroptera (microbats/echolocating bats), the Greater Noctule bat belongs to the Microchiroptera suborder.
trees that have a hollow space for day roosting. Greater Noctule Bats also roost in Pine trees if there are no other options. Other studies have shown that this bat greatly prefers Birch
trees. This suggests that the Greater Noctule Bat does not prefer a specific tree, but perhaps looks for the physical condition of the tree. It has been noted in several studies of Greater Noctule Bat roosting behavior that different trees have different functions for the Greater Noctule Bat, and that these tree specific needs could have an impact on roost selection for communities of Greater Noctule Bat. The studies in Hungary (Ke´ kes peak, 1014 m a.s.l.) indicates that Greater Noctule prefers high roost locations. The study also hypothesizes that older, decayed trees are preferred by the species.
which can possibly result in considerable seasonal changes in sex ratio. The studies in North-East Hungary indicates that the sex-ratio differs greatly depending on the location. Males were exceedingly dominant in Greece and the Czech Republic while females were dominant in NE Germany, the Moscow-region, Voronezh, and NE Hungary. This sexual segregation is due to difference in sex-specific thermoregulatory and energetic requirements. The females are dominant in warmer locations because it is optimal for fetal development and milk production. On the other hand, males are dominant in cooler locations because of lower energetic demands. These results verified that N. lasiopterus have nursing
colonies located in Hungary.
. These societies vary in size, but studies show that each society has a social order and is centralized around a specific group of trees that are used for roosting and breeding. The Greater Noctule Bat has been shown to travel between several roosting sites and to participate in several societies through radio tracking studies. It has been conjectured that ranking in society dictates different roles in society, e.g. some bats are scouts, others are hunters. There has been correlation between a specific bat's social ranking and the size of that bat's potential home range; the higher the social ranking, the lower the home range. The Greater Noctule Bat has an observed active range of 2500 km2. which is one of the largest observed ranges for any bat species. This large area of activity has several effects on the way the Greater Noctule Bat forages and roosts. It has been noted that changes by humans to the natural environment could have had an effect on the way the Greater Noctule Bat travels and roosts in its attempts to find suitable food sources. It has been noted that a lack of roosting sites near food sources could be the reason for the large home range that is displayed by the Greater Noctule Bat. Differences observed between two populations of bats with drastically different habitats, Great Britain and Spain respectively, show that the Greater Noctule Bat would not travel great distances for food unless absolutely necessary. This need to fly great distances for food has been theorized as a reason for the decline of the species. One study reported finding a Greater Noctule bat on the ground exhausted from flight. Another study of owl droppings found in areas in between GNB roosting sites has shown that the Greater Noctule bat is susceptible to predation in flight.
It has also been noted that the foraging range for the Greater Noctule bat increases during the lactating period for the Greater Noctule bat, potentially due to an increased need for energy. The Greater Noctule bat is also known to increase its foraging range in response to different levels of potential food sources. In the summer and fall months when water levels and insect abundance is lower in the northern parts of Europe the Greater Noctule bat has been found to increase its foraging range south to areas with a larger abundance of insects. The Greater Noctule bat is also one of the few known species of bat that also preys on nocturnally migrating birds. These birds tend to pause for rest during the day in the marshland fields that the Greater Noctule bat forages for insects in at night. When the birds start to migrate again at dusk the Greater Noctule bat is known to prey on them during fight. These changes in habitat based solely on food source suggest that the Greater Noctule bat is heavily dependent upon areas that can support its food supply regardless of how far it must travel to get to their prey.
The Greater Noctule bat also interacts with parasites that live in the trees that they roost in and transfer themselves to the bats while they are sleeping. The Greater Noctule bat also interacts with the few nocturnal flying predators in its area, mainly owls that are much larger than the bat. Evidence of Greater Noctule bat bones have been found in owl pellets.
(Tyto alba) and Eurasian eagle-owl (Bubo bubo). The Greater Noctule Bat generally leaves its roost to forage after it is already completely dark outside, this coincides with the general time that the two mentioned owl species hunt. There is also some risk to the Greater Noctule from parasitism between bats.
The species has not yet been well defined in their areas of roosting. Some have even been found to roost in caves and possibly housing, though whether this is typical behavior or an effect of displacement is uncertain. Tracking the species by radio signals, it was found that the species prefers older, larger trees, specifically beeches, perhaps due to possessing relatively spacious trunks and branches, allowing for ease of entry. The species does not have one specific roost, but a network through which the colony can rotate individuals. Recent years have seen less reliance on fossil fuels and rather relying on wood as a source of energy, and consequently an increase in logging, therefore it is important to locate the areas in which they roosts to identify those which should be protected to prevent their decline, through which radio tracking proves an effective method.
Description
The Greater Noctule bat belongs to the suborder Microchiroptera and uses echolocation. Echolocation is a perceptual system where echoes are produced by emitting ultrasonic sounds. Echolocation allows bats to compare the outgoing pulse with returning echoes which produces detailed images of the bat's surroundings. With echolocation, bats are able to detect, localize and classify their prey in complete darkness. The Greater Noctule Bat has been observed as only emerging from its roosts after dusk when it is completely dark. The Greater Noctule bat has a high quality of hearing and smell however its eyes are poorly developed.The wings of the Greater Noctule bat are thinner than those of birds which allow it to maneuver quickly and accurately. While its wing is delicate and rips easily, it is able to regrow. The Greater Noctule is one of the largest bats with a wingspan of up to 455 mm. Its total body length ranges from 152 to 162 mm and its forearm ranges from 62 to 68 mm. The Greater Noctule Bat has been observed as a high altitude flier and a low altitude forager. The dorsal fur of the Greater Noctule bat is uniformly reddish-brown to dark brown. Its muzzle is broad with enlarged short ears and its tragus is broad, short, and mushroom-shaped. Calcar, also known as calcaneum, is present and it reaches close to midway to the tail membrane.
The Greater Noctule bat has a robust skull and its rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
is square with an ordinary nasal
Nasal
Nasal may refer to:* Nose, a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for respiration in conjunction with the mouth...
slit. The zygomatic
Zygomatic
Zygomatic can refer to:* Zygomatic bone* Zygomatic branches of the facial nerve* Zygomaticus major muscle* Zygomaticus minor muscle* Zygomatic nerve* Zygomatic process** Zygomatic process of frontal bone...
arches are very slender and the braincase is smooth, turned upwards. The sagittal crest
Sagittal crest
A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull of many mammalian and reptilian skulls, among others....
is not present, while the lambdoid crest is well developed. Most of the projecting point of the skull is made up of exoccipital condyles. The basisphenoid is wide and deep and the tympanic bullae are relatively small.
Taxonomy and evolution
Even though the fossil record of bats (Chiroptera) extends over 50 million years, their fossils are extremely rare. The fossil record of vespertilionid greater noctule, Nyctalus lasiopterus, in the Iberian Peninsula suggest that they lived at different geographical locations from that of today. The fossils of Greater Noctule is almost non-existent prior to the Miocene epoch. The deterioration of the climate at the end of Neogene led to the disappearance of tropical species and thus vespertilionids profited by accessing a wider range of habitats.The Greater Noctule bat is a rare mammal in the order Chiroptera. It belongs to the family Vespertilionidae (vesper bats) and to the genus “Nyctalus” (noctule bats). Out of two traditionally recognized suborders Megachiroptera (megabats) and Microchiroptera (microbats/echolocating bats), the Greater Noctule bat belongs to the Microchiroptera suborder.
Habitat
Greater Noctule bat is a tree-dwelling bat that roosts in trees all year round. It is found throughout the deciduous forests of Europe from the Iberain Peninsula to the Bosporus region of Turkey. The largest concentration of Greater Noctule Bat is in the south western portion of Spain. The Greater Noctule Bat is a tree-obligate species that prefers Quercus or fagusBeech
Beech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.-Habit:...
trees that have a hollow space for day roosting. Greater Noctule Bats also roost in Pine trees if there are no other options. Other studies have shown that this bat greatly prefers Birch
Birch
Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...
trees. This suggests that the Greater Noctule Bat does not prefer a specific tree, but perhaps looks for the physical condition of the tree. It has been noted in several studies of Greater Noctule Bat roosting behavior that different trees have different functions for the Greater Noctule Bat, and that these tree specific needs could have an impact on roost selection for communities of Greater Noctule Bat. The studies in Hungary (Ke´ kes peak, 1014 m a.s.l.) indicates that Greater Noctule prefers high roost locations. The study also hypothesizes that older, decayed trees are preferred by the species.
Diet
Most bats are nocturnal creatures that consume insects, fruits, flower nectar, vertebrates, and blood. However, carnivory in bats (capturing other vertebrates excluding fish) has been found in one species of Nycteridae, four species of Megadermatidae, five species of Phyllostomidae, one species of Vespertilionidae and one species of Hipposideridae which adds to less than 1% of all bat species. While the majority of the world's bats are insect eaters, Greater Noctule bats regularly preys on birds. One study has shown that predation on birds accounts for over 80% of the Greater Noctule bat’s diet during periods of the year when the birds are migrating. The Greater Noctule Bat switches its prey type opportunistically depending on the time of year. In addition, with the possible exception of the Asian great evening bat http://scienceblogs.com/tetrapodzoology/2011/04/eptesicini_the_serotines.php, the Greater Noctule bat is the only bat that hunts birds on the wing rather than when roosting. The Greater Noctule is well adapted for hunting passerines in the air. It employs echolocation, is large in size, has wings with a wingspan of up to 46 centimeters that are evolved for open-air hunting, and has echolocation frequencies beyond the hearing range of birds.Mating and reproduction
The "N. lasiopterus"’ is understudied due to its rareness and very little information is found on the mating habit, reproductive pattern, life cycle and sex ratio of the species. “N. lasiopterus”, as “Nyctalus” species has an outstanding capability for migrationAnimal migration
Animal migration is the relatively long-distance movement of individuals, usually on a seasonal basis. It is a ubiquitous phenomenon, found in all major animal groups, including birds, mammals, fish, reptiles, amphibians, insects, and crustaceans. The trigger for the migration may be local...
which can possibly result in considerable seasonal changes in sex ratio. The studies in North-East Hungary indicates that the sex-ratio differs greatly depending on the location. Males were exceedingly dominant in Greece and the Czech Republic while females were dominant in NE Germany, the Moscow-region, Voronezh, and NE Hungary. This sexual segregation is due to difference in sex-specific thermoregulatory and energetic requirements. The females are dominant in warmer locations because it is optimal for fetal development and milk production. On the other hand, males are dominant in cooler locations because of lower energetic demands. These results verified that N. lasiopterus have nursing
Nursing
Nursing is a healthcare profession focused on the care of individuals, families, and communities so they may attain, maintain, or recover optimal health and quality of life from conception to death....
colonies located in Hungary.
Ecological interactions
The Greater Noctule Bat is known to participate in a fission-fusion societyFission-fusion society
In primatology, a fission-fusion society is one in which the social group, e.g. bonobo collectives of 100-strong, sleep in one locality together, but forage in small groups going off in different directions during the day. This form of social organization occurs in several other species of...
. These societies vary in size, but studies show that each society has a social order and is centralized around a specific group of trees that are used for roosting and breeding. The Greater Noctule Bat has been shown to travel between several roosting sites and to participate in several societies through radio tracking studies. It has been conjectured that ranking in society dictates different roles in society, e.g. some bats are scouts, others are hunters. There has been correlation between a specific bat's social ranking and the size of that bat's potential home range; the higher the social ranking, the lower the home range. The Greater Noctule Bat has an observed active range of 2500 km2. which is one of the largest observed ranges for any bat species. This large area of activity has several effects on the way the Greater Noctule Bat forages and roosts. It has been noted that changes by humans to the natural environment could have had an effect on the way the Greater Noctule Bat travels and roosts in its attempts to find suitable food sources. It has been noted that a lack of roosting sites near food sources could be the reason for the large home range that is displayed by the Greater Noctule Bat. Differences observed between two populations of bats with drastically different habitats, Great Britain and Spain respectively, show that the Greater Noctule Bat would not travel great distances for food unless absolutely necessary. This need to fly great distances for food has been theorized as a reason for the decline of the species. One study reported finding a Greater Noctule bat on the ground exhausted from flight. Another study of owl droppings found in areas in between GNB roosting sites has shown that the Greater Noctule bat is susceptible to predation in flight.
It has also been noted that the foraging range for the Greater Noctule bat increases during the lactating period for the Greater Noctule bat, potentially due to an increased need for energy. The Greater Noctule bat is also known to increase its foraging range in response to different levels of potential food sources. In the summer and fall months when water levels and insect abundance is lower in the northern parts of Europe the Greater Noctule bat has been found to increase its foraging range south to areas with a larger abundance of insects. The Greater Noctule bat is also one of the few known species of bat that also preys on nocturnally migrating birds. These birds tend to pause for rest during the day in the marshland fields that the Greater Noctule bat forages for insects in at night. When the birds start to migrate again at dusk the Greater Noctule bat is known to prey on them during fight. These changes in habitat based solely on food source suggest that the Greater Noctule bat is heavily dependent upon areas that can support its food supply regardless of how far it must travel to get to their prey.
The Greater Noctule bat also interacts with parasites that live in the trees that they roost in and transfer themselves to the bats while they are sleeping. The Greater Noctule bat also interacts with the few nocturnal flying predators in its area, mainly owls that are much larger than the bat. Evidence of Greater Noctule bat bones have been found in owl pellets.
Threats
The most common predators of Greater Noctule bat are barn owlBarn Owl
The Barn Owl is the most widely distributed species of owl, and one of the most widespread of all birds. It is also referred to as Common Barn Owl, to distinguish it from other species in the barn-owl family Tytonidae. These form one of two main lineages of living owls, the other being the typical...
(Tyto alba) and Eurasian eagle-owl (Bubo bubo). The Greater Noctule Bat generally leaves its roost to forage after it is already completely dark outside, this coincides with the general time that the two mentioned owl species hunt. There is also some risk to the Greater Noctule from parasitism between bats.
Endangered status
The Greater Noctule Bat is currently on the IUCN Red List of Threatened Species as 'data deficient' (IUCN, 2006), and is classified as 'vulnerable' in Spain (Ministerio de Medio Ambiente, 2006). No other country in Europe has a specific endangered status for the Greater Noctule Bat other than Spain.Conservation proposals
The organism separates itself socially and spatially with roosts. A colony has several roosts, with most of the populations centered in one large roost and several fringe roosts which other bat species may share. These are useful for sharing information between colonies. These roosts however can communicate disease and parasites. The individuals often fly from one roost to another to exchange information, and this also creates a pathway for infection. For reasons uncertain, such as being perhaps too advantageous to the colony, they continue to roost within these trees despite the disadvantages to themselves. It would be beneficial to the conservation of the species to locate the trees with roosts that have high levels of disease/ parasite infections in addition to high rates of transfers between roosts and cut them down to lessen the rate of infection among them. The functions of each roost also needs to be identified, as to understand which roosts would be better left intact. However, only day roosts studies were performed, and further research into their nocturnal habits may be required.The species has not yet been well defined in their areas of roosting. Some have even been found to roost in caves and possibly housing, though whether this is typical behavior or an effect of displacement is uncertain. Tracking the species by radio signals, it was found that the species prefers older, larger trees, specifically beeches, perhaps due to possessing relatively spacious trunks and branches, allowing for ease of entry. The species does not have one specific roost, but a network through which the colony can rotate individuals. Recent years have seen less reliance on fossil fuels and rather relying on wood as a source of energy, and consequently an increase in logging, therefore it is important to locate the areas in which they roosts to identify those which should be protected to prevent their decline, through which radio tracking proves an effective method.
External links
- BBC article: Bats eat flying birds, say scientists
- NPR article: Giant Bats Snatch Birds from Night Sky
- Darren NaishDarren NaishDarren Naish is a vertebrate palaeontologist and science writer. He obtained a geology degree at the University of Southampton and later studied vertebrate palaeontology under British palaeontologist David Martill at the University of Portsmouth, where he obtained both an M. Phil...
's blog Tetrapod Zoology: greater noctule predation on birds