Northern bat
| Northern bat | ||||||||||||
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Northern bat ( Eptesicus nilssonii ) hibernating in Norway |
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| Scientific name | ||||||||||||
| Eptesicus nilssonii | ||||||||||||
| Keyserling & Blasius , 1839 |
The northern bat ( Eptesicus nilssonii ) belongs to the bat family of the smooth-nosed bat (Vespertilionidae). The coat is characterized by a dark to black-brown basic color with ocher to leather-colored or golden hair tips from the crown to the base of the tail. The medium-sized species is distributed over large parts of Europe and Asia, with it mainly occurring in the northern regions. In Scandinavia it is one of the most common bat species. It is worldwide the bat with the northernmost range and also the only bat with proven reproduction north of the Arctic Circle .
The northern bat is predominantly nocturnal and usually flies out to hunt shortly after sunset. It feeds primarily on small insects with a body size of two to 20 millimeters, with small two-winged animals such as mosquitoes making up the majority. The females form nurseries with 10 to 100 individuals from April onwards and give birth to their young there. The animals hibernate from October to March or April.
The closest related species is the broad-winged bat ( Eptesicus serotinus ), which is also widespread in Europe , with which it is classified together in the genus of the broad-winged bat ( Eptesicus ) comprising 32 species . The species name honors the Swedish naturalist Sven Nilsson (1787–1883), who discovered the species and classified it a few years before the first two descriptions of it under an already known bat species.
features
general characteristics
The northern bat is a medium-sized species of bat. The information on the body size of the species varies greatly in the literature. According to Schober & Grimmberger (1998), the animals reach a head-trunk length of 45 millimeters as the extreme and 54.5 to 63.5 millimeters as the normal length, according to Rydell (1993) from 54 to 64 millimeters, according to Braun 2003 from 48 up to 64 millimeters as well as according to Gerell & Rydell 2011 after measurements on 15 individuals from Sweden from 45.1 to 55.8 millimeters. The weight is 8 to 17.5 grams according to Schober & Grimmberger and 8 to 12 grams according to Rydell as normal weight, whereby pregnant females can weigh up to 16 grams and maximum weights up to 18 grams were determined before hibernation. The tail reaches a length of 35 to 50 mm and the wingspan is 24 to 28 centimeters with a forearm length of 37 to 44 mm.
As with the broad-winged bat, the long and silky top coat is dark to black-brown at the base, but the hair tips of adult northern bats are colored ocher to leather-colored or golden from the crown to the base of the tail and thus form a contrast to the basic color. This effect occurs particularly in the shoulder area towards the middle of the back. The neck is darker and the belly side is very light yellow-brown in color, with the transition from the dark upper side to the light lower side being very sharply demarcated, especially on the sides of the neck. The muzzle, cheeks, ears and membranes are black. The young animals are darker in color and have no golden, but rather silvery hair tips, the belly is gray.
The ears are small compared to other bats and reach a length of 11.5 to 17.3 mm or 13 to 17.5 mm. Compared to the broad-winged bat, however, they are relatively larger. The tragus is short and slightly curved inward, the top edge is rounded and it is widest at the base of the front edge. The edge of the auricle has five distinct transverse folds and forms a membranous band that almost reaches the corners of the mouth.
The wings are medium in width and length with a rounded wing tip, with the fifth finger almost 10 millimeters longer than the forearm. The tail flight membrane has a narrow epiblema without a visible web and the calcar (spur) reaches about half the length of the tail flight skin length. The tail tip is 3 to 4 mm exposed with the last caudal vertebra .
In Europe, the northern bat is comparatively easy to distinguish from other bat species. Compared to the closely related broad-winged bat ( Eptesicus serotinus ) it is significantly smaller. It differs from other similar species, especially the two-colored bat ( Vespertilio murinus ) and the Alpine bat ( Hypsugo savii ), primarily in terms of coat color and features of the skeleton, especially the skull, and the shape of the penile bone . It is more difficult to differentiate between related species in the Asian part of their range. From the species Eptesicus bobrinskoi , Eptesicus gobiensis , Eptesicus nasutus and Eptesicus bottae occurring here , it can only be distinguished with certainty by very specific skull and tooth features.
Features of the skull
The skull of the northern bat is significantly smaller compared to that of the broad-winged bat, at the same time it is relatively higher and less elongated. The cranium is flat and viewed dorsally it is clearly convex in the middle. A sagittal crest is very indistinct and the snout is rounded at the sides. Similarities in the size and formation of the skull exist mainly to the two-colored bat, which, however, has noticeable pits between the eye socket and the nostril.
| 2 | · | 1 | · | 1 | · | 3 | = 32 |
| 3 | · | 1 | · | 2 | · | 3 |
The type has two front teeth (incisors), a canine (canine), a Vorbackenzahn (premolar) and three molars (Molar) in an upper jaw half and three cutting teeth, a canine, two Vorbackenzähne and three molars in the lower jaw half. The animals have a total of 32 teeth. The second, smaller incisor is very strong compared to that of the two-colored bat, which enables a reliable differentiation from this species.
genetics
The northern bat has a genome of 2n = 50 chromosomes and corresponds to other Eptesicus species. The X chromosome is metacentric, the small Y chromosome and all other chromosomes are acrocentric.
Calls
The northern bat can be recognized with the help of a bat detector based on the characteristic search flight sounds. Although these are very variable and modified in terms of sound duration, frequency and frequency modulation as well as the bandwidth, they have a characteristic end frequency in the range of 28 to 30 kHz. Compared with other species with similar calls, especially the Serotine and the little ones and Noctule ( Nyctalus leisleri or Nyctalus noctula ), this frequency is much higher.
The variations mainly depend on the environment in which the search sounds are emitted. The call duration in semi-open terrain is 8.3 to 13.4 milliseconds (ms) with a maximum bandwidth of 25 kHz and a repetition frequency of around 4 to 5 Hz (four to five calls per second), corresponding to a call with every second wing beat . The northern bat pauses of 178 to 297 ms between calls, which means that the calls are more discontinuous and slower than those of the broad-winged bat. Close to the vegetation, on the ground and in the vicinity of the roost, the pulse rates increase to around 10 Hz and the bandwidth increases sharply, while at higher altitudes they change into longer, constant-frequency calls with lengths of 13.0 to 17.7 ms, which occur at 28 run down to 29 kHz.
In addition to the calls used to search for food, these bats also communicate using so-called social sounds , especially within the roosts. These are loud and high-pitched, chirping calls and "bangs" in the spectrum from 10 to 58 kHz.
distribution and habitat
Distribution area
The northern bat has a large, Palearctic distribution area that extends from eastern France and Switzerland through central, northern and northern eastern Europe as well as northern Ukraine and Russia to the Pacific coast with Kamchatka , Sakhalin and Japan . In Mongolia , the species lives mainly in the north of the country in the northwestern Altai Mountains , the Chöwsgöl-Aimag , the Changai Mountains and the Chentii-Aimag, as well as in eastern Mongolia. The southern limit of distribution in Asia is largely unknown due to fewer finds and regular incorrect determinations and confusion with similar species. There is one single find for Iran .
The northern bat is worldwide the bat with the northernmost range of distribution and at the same time the only bat with proven reproduction north of the Arctic Circle . The evidence comes from the region near Luleå in Sweden (65 ° N), Troms (69 ° 05'N) and Øverbygd and Finnmark in Norway (70 ° 25'N). In Siberia it can be found up to about 60 ° N, although there is evidence from the Kola Peninsula (at 68 ° N), from the area around Arkhangelsk and from the northern Urals (both about 65 ° N).
The European distribution center is in the north and northeast of Europe to the Alps , the Caucasus and the Balkan Mountains as the southern distribution limit. The northern bat is one of the most common bat species in the Scandinavian countries, Finland, Estonia and Latvia. In western and southwestern Europe including Great Britain and the Iberian Peninsula , the Benelux countries and Denmark , the species is absent, in southern Europe it occurs only sporadically in southern France, northern Italy and the Balkans. The species is also found on various islands in the Baltic Sea such as Rügen , Gotland , Öland , Hiiumaa , Saaremaa and the Åland Islands .
In Central Europe, the northern bat is only sporadic and especially widespread in the low mountain ranges and in the foothills, because there it finds the same climatic conditions as in northern Europe. It is classified as rare in Poland , in the Czech Republic and Slovakia it is common in the north of the Carpathian Mountains and its evidence numbers decrease towards the lowlands. Numerous records are available for Germany; there are isolated occurrences mainly in the Harz , Sauerland , Vogelsberg , Westerwald , Hunsrück and Palatinate Forest . In the south to southeast, the distribution is continuous in the Thuringian Forest , the Ore Mountains , the Franconian Forest , the Upper Palatinate Forest , the Bohemian Forest and the Bavarian Forest as well as on the Swabian Alb and in the Black Forest . Numerous records are also available for Austria and Switzerland , with the density of records decreasing towards eastern France , Italy , Hungary , Romania , Croatia and the Balkan Peninsula. The Eastern European distribution area extends over the Ukraine and the Caucasus to the neighboring regions of Russia, Georgia , Armenia , Azerbaijan ; Evidence east of the Black Sea is rare, however.
habitat
Northern bats prefer loose bush and coniferous forest areas at altitudes of 200 to over 2,000 meters as a habitat, especially in Europe. They have been found in the mountains up to over 2,290 meters in the Alps , and winter finds in caves were up to 2200 meters. The highest known nursery was also in the Alps at an altitude of 1660 meters. They are also tied to more humid habitats and the proximity of water. For southern Thuringia, a distance between the nursery roosts of 100 to 500 meters to the nearest flowing water was determined and in other areas rivers in the area of the roosts were also found to be important components of the habitat. In addition, there is a link to human settlements, as the nurseries in particular are very often found on the roofs of heated houses. Although most of the finds are made from winter quarters in remote caves and cellars, it can be assumed that a large proportion of the bats may overwinter in inaccessible places in wall coverings and roofs.
In Asia they can also be found in extensive forest areas, the taiga and steppes - to desert areas as well as in cultivated land.
Way of life
The northern bat is mainly nocturnal and flies out to hunt shortly after sunset. The foraging flights take place irregularly and depending on the weather, especially in mild weather. In September to October they are less frequent and completely stopped at the time of hibernation. Usually the females leave their roosts around 40 minutes after sunset and return before sunrise. During the gestation period, they hunt mainly just after dusk and just before dawn. At temperatures below 6 to 7 ° C, the animals stay in the roosts because of the inefficiency of foraging for food.
The summer quarters and nursery rooms that are occupied from April onwards are often on or in houses covered with slate, wood and tin, behind chimneys, in the roof and behind shutters. During the day, the bats rest in crevices on buildings and rocks, individual animals rest in tree hollows or in wood piles. Abandoned mine tunnels and caves can also be used as transitional quarters, especially by male animals.
nutrition
The northern bat's diet consists of small, nocturnal and crepuscular insects with a body size of two to 20 millimeters, with small two-winged bats of three to 10 millimeters making up the main part with 30 to 80% of the diet. This is mainly to mosquitoes (Nematocera), especially midges (Chironomidae). In addition, the bats feed opportunistically on other flying insects such as beetles (Coleoptera, mainly dung beetles ), Hymenoptera (Hymenoptera, mainly ants), caddis flies (Trichoptera), mosquitoes (Tipulidae), Flying (Brachycera), alderfly (Sialidae), stoneflies ( Plecoptera), butterflies (Lepidoptera) and earwigs (Dermaptera). After Brown 2003, they prey on small spiders (aranaea), harvestmen (Opiliones) and Bug . According to Gerell & Rydell 2011, all prey animals are caught and eaten in flight, with many insects with aquatic larvae being caught from the surface of the water after hatching.
The hunting flight of the animals is very fast with a speed of 5 to 6 meters per second and takes place with rapid turns, in hunting breaks they hang on to branches. The flights take place at a height of 2 to 50, usually 5 to 20 meters. In the area of trees, the animals always hunt a few meters away from the vegetation at the height of the greatest leaf density at around 5 to 15 meters, in open terrain and over water they hunt at a height of 2 to 5 meters above the ground. The hunt for this species can often take place in the light of street lamps or on illuminated house areas, especially in autumn and spring, where it primarily preyes on night butterflies.
Especially females often hunt in small groups near the roost in the nursery area and can defend them against other conspecifics. Pregnant females hunt for about 150 minutes per night, suckling females immediately after birth for about 130 minutes and more with increasing suckling time and up to 320 minutes at the end of the same.
Reproduction and development
Copulations probably take place in autumn and early winter, sometimes in the winter quarters. As with other bats, the females store the sperm in the female genital tract until ovulation and fertilization in spring.
The maternity roosts of the females are formed around April and consist of around 10 to 100, on average 75 individuals. Compared to many other bat species, they are very small and consist of both birthing and non-birthing females, while males are absent. 70% or more of the adult females return annually to the same nursery, which is also often the nursery of their birth. As a rule, females do not give birth until they are four years old. There is no mixing of different nursery communities, but the females often change roosts while rearing their young, transporting the young animals that are not yet able to fly. Typical nursery roosts are above all the roofs of heated houses.
The time of birth varies from region to region. While the young are born in Germany from mid-June, the births in southern Scandinavia towards the end of June and further north in July. It is assumed that the birth is delayed if the temperatures are low during the early gestation period and the females accordingly fall into a torpor . In Scandinavia a young is usually born, in more southern regions twin births can occur more frequently. The birth lasts a few minutes, during which the mother hangs upside down and the tail skin bends towards the body. The young animals have a body length of 45 to 48 millimeters and a forearm length of 12.5 to 14 millimeters at birth. They are completely naked and their eyes are closed, and shortly after birth they utter "calls to be abandoned".
The young are independent in Sweden after about 15 to 17 days and in Germany after about three weeks, so that the first outing and hunting flights take place in July. From the end of July to the beginning of August, the nurseries dissolve, with the animals then retreating to deeper and more nutrient-rich areas. The females reach sexual maturity after about 2 to 3 years. The maximum documented age is given as around 15 years, the average maximum age of the animals is probably significantly lower. A mean life expectancy of the females of 2.25 years was determined for a colony in southern Thuringia.
Winter quarters
The animals hibernate from October to March or April , although the times can vary from region to region. They spend the winter in small groups or as a single animal in crevices, caves, cellars or tunnels and sleep hanging on the wall and ceiling, squeezed into crevices or on the floor. When the temperature is warmer, they interrupt their hibernation and leave their quarters, but they can also change their quarters. Socialization with bats of other species is rare.
The preferred temperature of the winter roosts is 1 to 5.5 ° C, but may briefly drop to −5.5 to −7 ° C. The species is accordingly weather-hard and cold-tolerant. In Austria they were found in real ice caves, among other places, and overwintered in non-frost-free rooms. However, dead animals and animals trapped in ice were also found.
Enemies and parasites
The predators of the northern bat include mainly owl species such as the eagle owl ( Bubo bubo ) and the tawny owl ( Strix aluco ), birds of prey such as the sparrowhawk ( Accipiter nisus ) and the tree falcon ( Falco subbuteo ) as well as the domestic cat .
Six different flea species of the genus Ischnopsyllus and Myodopsylla trsellis have been documented as parasites of the northern bat . The northern bat is also the host for the mites Spinturnix kolenatii , Macronyssus flavus , Neomyobia chiropteralis and Ichoronyssus biarcuatus . Bat flies and flat bugs , which are common in other bat species, have not been described in the northern bat. Species-specific endoparasites of the northern bat are not known, the documented roundworms correspond to those of other bat species. There is no evidence that northern bats transmit rabies or other diseases that are dangerous to humans.
Fossil record
While the oldest finds of Eptesicus species come from the early Pliocene , the northern bat could be detected for the first time in the early to middle Pleistocene . Up to 1993, fossil finds from at least 17 locations in Central Europe were known, mainly from cave finds. Evidence exists for Russia from the late Pleistocene and Holocene from Crimea , Siberia and Eastern Russia.
Fossil finds in Central Europe are particularly common in the late Pleistocene 600,000 to 100,000 years ago and in the Holocene, with the northern bat being detected in 40% of the sites. This suggests that at this time there was a shift in the bat fauna of Central Europe to more northerly species such as the northern bat. Finds from Belgium and northern Bulgaria, also from the Pleistocene, indicate that the species also occurred in areas where it can no longer be found today, especially during cold periods.
Systematics
The first scientific description of the species was made by Alexander Keyserling and Johann Heinrich Blasius in 1839 as V [esperugo] nilssonii in an article on the "Overview of the genus and species characters of European bats". As early as 1836, the Swedish naturalist Sven Nilsson described the species based on an animal caught in Norway under the name Vespertilio kuhlii and assigned it to the white-rimed bat . Nilsson then presented another description as Vespertilio borealis in 1838 .
Keyserling and Blasius used the northern bat as an example for their statement that "really new species are being described again under the name of older ones". In their first description they named the bat after Nilsson with the species name nilssonii . The first assignment to the genus Eptesicus described by Constantine S. Rafinesque-Schmaltz in 1820 under the now recognized name Eptesicus nilssonii was made by the American zoologist Gerrit Smith Miller in 1907.
The northern bat , together with the broad-winged bat ( Eptesicus serotinus ), which is also widespread in Europe, is assigned to the genus of the broad-winged bat ( Eptesicus ), which consists of 32 recent species worldwide . It is very closely related to the broad-winged bat and could also be paraphyletic in relation to this species . A phylogenetic investigation of the genus is not yet available.
Two subspecies have been described. The nominate form Eptesicus nilssonii nilssonii is found in most of the European and Asian distribution area, while Eptesicus nilssonii parvus occurs only in North Korea , on the Sakhalin Peninsula and the Japanese island of Hokkaidō . In 1993 Rydell established the Eptesicus japonicus, which lives on Honshū and is now established as a separate species, as a subspecies of the northern bat, but did not recognize Eptesicus nilssonii parvus as a subspecies.
Threat and protection
The species is globally assessed by the International Union for Conservation of Nature and Natural Resources (IUCN) as "Least Concern" due to its large distribution area and population size. A decline in the population and a serious threat to the species are not known. Instead, Gerell & Rydell 2011 state that there is evidence that the species has become more common regionally.
The northern bat is listed nationally and regionally in most European countries in the Red Lists of Endangered Species and is accordingly protected by national legislation. In Germany, for example, it is protected as a particularly endangered species by the Federal Species Protection Ordinance (BArtSchV). Cross-border protection takes place via the EU Species Protection Ordinance , and the Agreement on the Conservation of European Bat Populations (EUROBATS), according to which the deliberate trapping, keeping and killing of bats is legally prohibited in the contracting states , exists for bats in particular .
The northern bat is also listed in Appendix IV of the European Fauna-Flora-Habitat Directive . In Annex IV of the Fauna-Flora-Habitat Directive, the EU lists species that are to receive special protection outside of designated protected areas. The species in Appendix IV cannot be effectively protected simply by designating protected areas; B. because of scattered or unstable occurrences, special or particularly large-scale habitat requirements and dependence on special land use practices. With species like the northern bat, their habitats (here nurseries, feeding areas and winter quarters) must not be impaired or destroyed - regardless of where they are. So this applies z. B. also for nurseries in buildings. In practice, the implementation of construction projects such as road construction and other interventions on areas that are living space may be considerably more difficult. Destruction of habitats that would threaten a local population is legally only possible if special compensatory measures under species protection law (so-called CEF measures , "Continuous ecological functionality measures", translation: "Measures for the permanent protection of the ecological function") are carried out. In contrast to normal compensatory measures (due to the intervention regulation in nature conservation law), proof of success is required here, not just a success prognosis as with other interventions. The compensation measures must therefore be carried out prior to the intervention, e.g. B. the construction project.
supporting documents
- ↑ a b c d e f g h i j k Schober & Grimmberger 1998 ; Pp. 160-162.
- ↑ a b c d e f g h i Rydell 1995 ; Section “General Characters”, pp. 1–2.
- ↑ a b c d Braun 2003 ; Description Section, pp. 507–509.
- ↑ a b Gerell & Rydell 2011 ; Diagnosis Section, pp. 560–563.
- ↑ a b c d e f Gerell & Rydell 2011 ; Description Section, pp. 563-565.
- ↑ a b Rydell 1995 ; Section "Diagnosis", p. 1.
- ↑ Rydell 1995 ; Section “Genetics”, p. 2.
- ↑ a b c d e f g h i j k l m n o p q r Braun 2003 ; Section “Way of Life”, pp. 512-516.
- ↑ a b c d Rydell 1995 ; Section “Distribution”, p. 2.
- ↑ a b c d e f g h i Gerell & Rydell 2011 ; Description Section, pp. 567-570.
- ↑ a b c d e Eptesicus nilssonii in the Red List of Endangered Species of the IUCN 2011. Posted by: M. Stubbe, J. Ariunbold, V. Buuveibaatar, S. Dorjderem, Ts. Monkhzul, M. Otgonbaatar, M. Tsogbadrakh, AM Hutson, F. Spitzenberger, S. Aulagnier, I. Coroiu, 2008. Retrieved December 17, 2011.
- ↑ Braun 2003 ; Section “Habitats”, pp. 511–512.
- ↑ a b Gerell & Rydell 2011 ; Section “Ecology”, pp. 571–573.
- ↑ a b Gerell & Rydell 2011 ; Activity Section, pp. 575–576.
- ↑ a b c Gerell & Rydell 2011 ; Section “Food”, p. 573.
- ↑ a b c d e Gerell & Rydell 2011 ; “Reproduction,” pp. 573-574.
- ↑ a b Gerell & Rydell 2011 ; Section “Population Dynamics,” p. 574.
- ↑ Gerell & Rydell 2011 ; Parasites Section, pp. 574–575.
- ↑ a b Rydell 1995 ; Section “Fossil Record”, p. 2.
- ↑ Gerell & Rydell 2011 ; Section “Paleontology”, p. 571.
- ↑ a b Braun 2003 ; Section “Naming”, p. 507.
- ↑ a b Rydell 1995 ; Section “Context and Content”, p. 1.
- ↑ a b Don E. Wilson & DeeAnn M. Reeder (eds.): Eptesicus nilssonii ( Memento of the original from April 18, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. in Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed).
- ↑ MUNLV (2007): Protected species in North Rhine-Westphalia . Dusseldorf
- ↑ Fauna-Flora-Habitat Directive and Bird Protection Directive - Areas and Species in Germany. Natura 2000; List of the species occurring in Germany in Annex IV and V of the Fauna Flora Habitat Directive
literature
- Rune J. Gerell, Jens Rydell: Eptesicus nilssonii (Keyserling et Blasius, 1839) - Northern bat. In: Franz Krapp (Ed.): The bats of Europe. Extended special edition from the Handbook of Mammals in Europe. AULA-Verlag, Wiebelsheim 2011, pp. 561-581, ISBN 978-3-89104-751-4 .
- Jens Rydell: Eptesicus nilssonii . In: Mammalian Species . tape 430 , 1995, pp. 1–7 ( full text (PDF file; 842 kB)).
- Monika Braun: Northern bat Eptesicus nilssonii (Keyserling & Blasius, 1839). In: Monika Braun, Fritz Dieterlen (Hrsg.): Die Säugetiere Baden-Württemberg. Volume 1 Bats (Chiroptera). Verlag Eugen Ulmer, Stuttgart 2003, pp. 507-516, ISBN 3-8001-3282-6 .
- Wilfried Schober, Eckhard Grimmberger: The bats of Europe - know, determine, protect. 2nd updated edition, Franckh-Kosmos Verlags-GmbH, Stuttgart 1998, pp. 160–162, ISBN 3-440-07597-4 .
Web links
- Eptesicus nilssonii in the endangered Red List species the IUCN 2011. Posted by:. M. Stubbe, J. Ariunbold, V. Buuveibaatar, p Dorjderem, Ts Monkhzul, M. Otgonbaatar, M. Tsogbadrakh, AM Hutson, F. Spitzenberger, S. Aulagnier, I. Coroiu, 2008. Retrieved December 17, 2011.
