El ratpenat de cua de beina de les Seychelles (Coleura seychellensis) viu a les illes Seychelles.
És un dels animals més amenaçats d'extinció del planeta, ja que es creu que no n'hi ha més de 100 exemplars.
El ratpenat de cua de beina de les Seychelles (Coleura seychellensis) viu a les illes Seychelles.
És un dels animals més amenaçats d'extinció del planeta, ja que es creu que no n'hi ha més de 100 exemplars.
Die Seychellen-Schiebeschwanz-Fledermaus (Coleura seychellensis) ist eine seltene, vom Aussterben bedrohte[1] Fledermausart aus der Familie der Glattnasen-Freischwänze (Emballonuridae). Sie kommt ausschließlich auf den Seychellen-Inseln Silhouette und Mahé vor. Ehemalige Kolonien auf La Digue und Praslin sind erloschen.
Die Seychellen-Schiebeschwanz-Fledermaus erreicht eine Kopf-Rumpf-Länge von 55 bis 65 mm. Die Schwanzlänge beträgt 12 bis 20 mm, die Unterarmlänge 45 bis 56 mm und die Ohrenlänge 14,0 bis 15,9 mm. Bei den Männchen wurde ein Gewicht von 10,2 g gemessen, bei den Weibchen ein Gewicht von 11,1 g. Diese kleine Fledermaus hat ein rötlich braunes oder dunkelbraunes Fell mit einer helleren Unterseite. Der Trivialname Schiebeschwanz-Fledermaus bezieht sich auf eine Membran zwischen den Hinterbeinen. Durch die Stellung der Hinterbeine im Flug kann diese Membran verlängert oder verkürzt werden; sie schiebt sich über den Schwanz, was die Wendigkeit beim Fliegen vergrößert.
Die Seychellen-Schiebeschwanz-Fledermaus ist in den Küstengebieten anzutreffen. Ihre Wochenstube und die Schlafstellen befinden sich in Felshöhlen. Eine Studie aus dem Jahr 2006 über die Nahrungssuche und die Aktivitätsmuster legte dar,[2] dass die untersuchten Individuen nicht nur den Küstenwald für ihre Schlafstellen bevorzugten, sondern auch bei der Nahrungssuche nahe an der Küste verblieben. Suchen nach der Art im Hochland schlugen fehl und nahezu alle Aufzeichnungen von Aktivitätsmustern stammen aus Küstenlebensräumen. Die Art benötigt vielfältige natürliche Waldhabitate mit einem reichhaltigen Insektenbestand, insbesondere mit Nachtfaltern und Käfern.
Die Art ist nachtaktiv und ernährt sich ausschließlich von Insekten. Bei Tageslicht ruhen die Fledermäuse in Höhlen. Wenn sie aufgeschreckt werden, klammern sich die Tiere oft mit allen vier Gliedmaßen und ihren Bäuchen an die Deckenoberfläche. Wenn sie entspannt sind, hängen sie mit ihren Füßen von der Decke. Die Weibchen bringen ihr einziges Junges während der Regenzeit (von November bis Dezember) zur Welt; manchmal auch zwischen März und April.
Es werden zwei Unterarten der Seychellen-Schiebeschwanz-Fledermaus unterschieden: Coleura seychellensis seychellensis, die auf Mahé vorkommt und Coleura seychellensis silhouettae von der Insel Silhouette, die 1915 von Oldfield Thomas als eigenständige Art Coleura silhouettae beschrieben und 1971 von John Edwards Hill (1928–1997) als Unterart klassifiziert wurde. Beide Unterarten lebten in der Vergangenheit auch auf den Inseln La Digue und Praslin, diese Populationen sind jedoch seit 1980 beziehungsweise 2001 erloschen.
Die IUCN listet die Seychellen-Schiebeschwanz-Fledermaus in der Kategorie „vom Aussterben bedroht“ (critically endangered). Im Jahr 2010 wurde der Gesamtbestand auf circa 90 Exemplare geschätzt.
Die Seychellen-Schiebeschwanz-Fledermaus (Coleura seychellensis) ist eine seltene, vom Aussterben bedrohte Fledermausart aus der Familie der Glattnasen-Freischwänze (Emballonuridae). Sie kommt ausschließlich auf den Seychellen-Inseln Silhouette und Mahé vor. Ehemalige Kolonien auf La Digue und Praslin sind erloschen.
The Seychelles sheath-tailed bat (Coleura seychellensis) is a sac-winged bat found in the central granitic islands of the Seychelles. They are nocturnal insectivores that roost communally in caves. The species was previously abundant across much of the archipelago, but has since seen a substantial loss of habitat. The International Union for Conservation of Nature has listed the species as being critically endangered, due to population decline. This is mainly due to an increase in land development and the introduction of invasive species.
The weight of Seychelles sheath-tailed bats averages about 10–11 grams (0.35–0.39 oz). Bats in this genus generally roost in caves and houses, in crevices and cracks. In the 1860s, the Seychelles sheath-tailed bat was reported to fly around clumps of bamboo towards twilight, and in the daytime to be found roosting in the clefts of the mountainside facing the sea and with a more or less northern aspect. These hiding places were generally covered over with the large fronds of endemic palms. The Seychelles sheath-tailed bat is insectivorous. It feeds predominantly on marsh-associated Ceratopogonidae, in contrast to Curlionidae in palm woodland. Its colonies are apparently divided into harem groups.
It has been the focus of recent intensive research, which has determined that it is a species associated with small clearings in forests where it feeds on a wide variety of insect species. Observations of coastal or marsh feeding are thought to be bats that have been forced into feeding in unusual situations due to habitat deterioration. Although the species is not a specialist and has a high reproductive potential, it is very vulnerable to disturbance and requires several roost sites within healthy habitat.
It was probably abundant throughout the Seychelles in the past, but it has declined drastically and is now extinct on most islands. The International Union for Conservation of Nature lists this bat as being critically endangered.[1] In 2013, Bat Conservation International listed this species as one of the 35 species of its worldwide priority list of conservation.[2]
It is one of the most endangered animals, fewer than 100 are believed to exist in the world. The Seychelles sheath-tailed bat has suffered from habitat deterioration due to the effects of cultivation of coconut plantations and the introduction of the kudzu vine, both of which have reduced the incidence of scrub and the availability of insect prey.[1] The largest surviving roost is on Silhouette Island, although small roosts do exist in Mahé and also Praslin and La Digue islands.[1] Its lifespan is 20 years; its length is 55–65 mm (2.2–2.6 in). It finds its mates by fighting with another male bat in front of the females.
Echolocation in bats is the combination of producing sound waves via a bat's vocalization, using echoes from an environment, and highly evolved ears in bats. These sound waves are projected from an origin (the individual bat) until they come upon an object and are promptly bounced back to the origin at a lesser frequency and received by the source individual.[3] The variation in the return frequency can then be used by the individual to make a "visual" map of the environment in order for the bat to find their food or perform other tasks such as navigation as well as just communicating with other individuals in the colony.[3] There are a few different and important variables that can affect acoustic signals and soundwaves, first of which includes time/length (temporal character) of the calls by an individual.[3] Temporal control can be important in perceptual organization of echoes as they are returning back to a source individual from various directions and distances.[3] A second variable is speed/rate (spectral character) at which an individual calls and is important in helping an individual to perceptually visualize their surroundings when they are flying through terrain.[3] The speed (frequency) that an individual calls also can become faster as they close the distance between themselves and a food source, which is how they hunt flying insects such as Lepidoptera.[4] The speed at which calls can be adjusted from an individual also is important to keep track of each echo in more complex audio terrain.[3]
In order to use echolocation effectively bats have gone through much evolution to specialize in this method of movement and hunting. The two evolutionary pathways of echolocation in the two current suborders of bats, Yinpterochiroptera and Yangochiroptera are first, that echolocation has evolved separately between the two suborders, and second, that echolocation evolved from a single point in bat ancestral history and later was lost in some, but not all, Yinpterochiroptera suborder species.[5] There are two different structures that can be utilized for the inner ear of bats, the wall-less canal or the fenestral canal.[5] The wall-less canal allows for ganglion axons to cluster together without restrictions and allows for more space for more neurons.[5] The fenestral canal is more restrictive and does not allow for the increase of space for more neurons and also does not allow the clustering of ganglion axons which makes this structure more restrictive when concerning the variation of ganglion.[5] The highly derived spiral ganglion structure of the inner ear in Yangochiroptera, the suborder of Coleura seychellensis, is referred to as a trans-otic ganglion with a wall-less Rosenthal canal and is what makes echolocation work so well in bats of a similar evolutionary pathway.[5]
Within echolocation, there is vocalization which can be best described as how a frequency is altered for different purposes and needs. At a family level (Emballonuridae) four call structures have been described, broadband FM (Frequency modulation), narrowband FM, long multi-harmonic calls and short multi-harmonic calls.[6] Broadband FM is simply an FM sweep, narrowband FM is a downwards FM sweep that is then followed by a more narrow band tail. Long multi-harmonic calls are calls that have a minimum of 4 narrowband FM harmonics in a 2 ms period. Similarly, short multi-harmonic calls are ones that also have 4 narrowband FM harmonics but in under 2 ms.[6] The structure of calls can be altered for a specific need, they can be faster, slower, louder, or quieter from a source individual depending if they are hunting, navigating, communicating, protecting territory, or courting a mate. To date, there are 21 simple syllables and 62 composite syllables in Saccopteryx bilineata males which are in the same family, Emballonuridae, as Coleura seychellensis.[7]
Using these syllables there are seven vocalization types in the species S. bilineata, identified as pulses, barks, chatter, whistles, screeches, territorial songs, and courtship songs.[8] Pulses have a CF (constant frequency), start with an upward FM hook, end with a downward FM hook, and last about 7.4 ms.[8] Barks are similar to pulses but are longer at about 10.5 ms and mainly come from males.[8] Chatter calls are in sequences of up to 50 calls in about 5.5 ms, a single chatter call can resemble pulses but usually has a higher degree of FM.[8] Whistles are very loud and tonal vocalizations by males hovering in front of females and last about 66.7 ms, start with a FM upstroke, increasing in fundamental frequency, and end with a FM downstroke.[8] At the same time females vocalize a screech that can last up to 300 ms and are related to territorial conflicts and response to males hovering, these calls, also vocalized by males, typically have a duration of about 97 ms.[8]
Territorial songs are the most noticeable vocalizations in a colony with 10-50 tonal calls that first have an upward FM, then a V-shaped call in the middle, ending with a lower fundamental frequency that is headed by a noisy buzz.[8] The territorial calls can last anywhere from 10 ms to 100 ms and their structure can vary throughout the day.[8] Complex songs in mammals are rare and uncommon in S. bilineata but are used as courtship songs by males. The complex courtship songs also allow for individual identification of males by females in the species S. bilineata.[8] These courtship calls will only happen after territorial calls are finished in the morning and before territorial calls start in the evening and require ultrasound recording systems because they are above 20 kHz, that is, out of human hearing range (About 20 Hz - 20 kHz).[8] These courtship songs also can last for up to 1 hour while being directed at a single female.[8] As mentioned, S. bilineata are in the same family as C. seychellensis and while there is not as much known for C. seychellensis, 4 types of calls have been categorized specifically for C. seychellensis: complex calls, orientation calls, orientation calls in open areas, and foraging calls.[9]
Complex social calls have a wide frequency range and are mainly directed at other bats with no repetition in call structure.[9] Orientation calls are used for orientation in various terrains, usually in confined spaces.[9] Orientation calls in open areas involve no changes in frequency or amplitude.[9] Last, foraging calls are similar to orientation calls in open areas but include two alternating CF pulses.[9] Lower frequencies are usually used for navigation in C. seychellensis while higher frequencies are used for prey detection when an individual is in a more clustered environment.[9]
The Seychelles sheath-tailed bat (Coleura seychellensis) is a sac-winged bat found in the central granitic islands of the Seychelles. They are nocturnal insectivores that roost communally in caves. The species was previously abundant across much of the archipelago, but has since seen a substantial loss of habitat. The International Union for Conservation of Nature has listed the species as being critically endangered, due to population decline. This is mainly due to an increase in land development and the introduction of invasive species.
Coleura seychellensis es una especie de murciélago de la familia Emballonuridae.
Es endémica de Seychelles, solo se puede encontrar en las islas de Silhouette y prasina Mahe.
Es uno de los animales más amenazados de extinción del planeta ya que se cree que no hay más de 100 ejemplares.
Coleura seychellensis es una especie de murciélago de la familia Emballonuridae.
Coleura seychellensis Coleura generoko animalia da. Chiropteraren barruko Emballonurinae azpifamilia eta Emballonuridae familian sailkatuta dago
Coleura seychellensis Coleura generoko animalia da. Chiropteraren barruko Emballonurinae azpifamilia eta Emballonuridae familian sailkatuta dago
Coleura seychellensis est une espèce de mammifères chiroptères (chauves-souris), insectivores, de la famille des Emballonuridae, endémique des îles Mahé et Silhouette aux Seychelles. Il fait partie de la liste des 100 espèces les plus menacées au monde établie par l'UICN en 2012.
L'espèce endémique est uniquement présente dans deux grottes situées sur les îles Mahé et Silhouette aux Seychelles.
Coleura seychellensis est une espèce de mammifères chiroptères (chauves-souris), insectivores, de la famille des Emballonuridae, endémique des îles Mahé et Silhouette aux Seychelles. Il fait partie de la liste des 100 espèces les plus menacées au monde établie par l'UICN en 2012.
Coleura seychellensis (Peters, 1868) è un pipistrello della famiglia degli Emballonuridi endemico delle Seychelles.[1][2]
Pipistrello di medie dimensioni, con la lunghezza dell'avambraccio tra 52 e 57 mm, la lunghezza del piede tra 8,5 e 10,3 mm e la lunghezza delle orecchie tra 14 e 15,9 mm.[3]
La pelliccia è relativamente corta. Il colore generale del corpo è marrone scuro. Il muso è largo ed appiattito. Le narici si estendono oltre il labbro inferiore dove è presente un solco longitudinale. Le orecchie sono relativamente corte, appuntite, con il bordo anteriore diritto e quello posteriore leggermente concavo e con una rientranza a metà lunghezza. Il trago è lungo, con i bordi paralleli, l'estremità arrotondata e un lobo alla base posteriore. Le membrane alari sono lunghe, strette e attaccate posteriormente sulle caviglie. La coda è lunga e fuoriesce dall'uropatagio a circa metà della sua lunghezza. Il calcar è lungo circa quanto la tibia.
Emette ultrasuoni a basso ciclo di lavoro sotto forma di impulsi di breve durata a frequenza quasi costante tra 37,9 e 40,4 kHz.
Si rifugia in gruppi fino a 30-40 individui all'interno di grotte tra ammassi rocciosi con basse temperature stabili ed accesso verso i palmeti e le paludi. Necessita di caverne con volte orizzontali e vie d'uscita libere dalla vegetazione.
Si nutre di insetti, in particolare lepidotteri, coleotteri, imenotteri e ditteri.
Gli accoppiamenti avvengono probabilmente da dicembre a marzo. Danno alla luce un piccolo alla volta, il quale raggiunge le dimensioni adulte dopo 29 giorni. Lo svezzamento avviene dopo 4 mesi.
Questa specie è conosciuta soltanto sulle isole di Silhouette e nella parte nord-occidentale di Mahé, nelle Isole Seychelles. Si è estinta a partire dal 1980 sulle altre due isole di La Digue e Praslin.
Vive nei caratteristici affioramenti rocciosi dell'arcipelago in prossimità di boschi e paludi.
Sono state riconosciute 2 sottospecie:
La IUCN Red List, considerato che la popolazione è ridotta a poco più di 100 individui, raggruppati in gruppi di almeno 50 esemplari ciascuno e soggetta ad un continuo declino, classifica C.seychellensis come specie in grave pericolo (CR).[1]
La Società Zoologica di Londra, in base ad alcuni criteri evolutivi e demografici, la considera una delle 100 specie di mammiferi a maggior rischio di estinzione.
Coleura seychellensis (Peters, 1868) è un pipistrello della famiglia degli Emballonuridi endemico delle Seychelles.
De seychellenkokerstaartvleermuis (Coleura seychellensis) is een zoogdier uit de familie van de schedestaartvleermuizen (Emballonuridae). De wetenschappelijke naam van de soort werd voor het eerst geldig gepubliceerd door Peters in 1868.
Bronnen, noten en/of referenties
Coleura seychellensis é uma espécie de morcego da família Emballonuridae. Endêmica das Seicheles, pode ser encontrada somente nas ilhas de Silhouette, Mahé e Praslin.
Coleura seychellensis é uma espécie de morcego da família Emballonuridae. Endêmica das Seicheles, pode ser encontrada somente nas ilhas de Silhouette, Mahé e Praslin.
Coleura seychellensis[2][3] är en fladdermusart som beskrevs av Peters 1868. Coleura seychellensis ingår i släktet Coleura och familjen frisvansade fladdermöss.[4][5]
Inga underarter finns listade i Catalogue of Life.[4] Wilson & Reeder (2005) skiljer mellan två underarter.[6]
Denna fladdermus förekommer endemisk på södra Seychellerna. I norra delen av ögruppen är den troligen utdöd. Arten vilar i kyliga grottor nära kusten och söker föda i grupper av palmer eller i marskland.[1]
Coleura seychellensis hotas främst av habitatförstöring. Dessutom täcker den introducerade klätterväxten Pueraria phaseoloides grottor som tidigare var lämpliga viloplatser. Fladdermusen jagas av införda fiender som tornuggla och tamkatt. IUCN kategoriserar arten globalt som akut hotad (CR).[1]
Wikimedia Commons har media som rör Coleura seychellensis.
Wikispecies har information om Coleura seychellensis.
Coleura seychellensis är en fladdermusart som beskrevs av Peters 1868. Coleura seychellensis ingår i släktet Coleura och familjen frisvansade fladdermöss.
Inga underarter finns listade i Catalogue of Life. Wilson & Reeder (2005) skiljer mellan två underarter.
Denna fladdermus förekommer endemisk på södra Seychellerna. I norra delen av ögruppen är den troligen utdöd. Arten vilar i kyliga grottor nära kusten och söker föda i grupper av palmer eller i marskland.
Coleura seychellensis hotas främst av habitatförstöring. Dessutom täcker den introducerade klätterväxten Pueraria phaseoloides grottor som tidigare var lämpliga viloplatser. Fladdermusen jagas av införda fiender som tornuggla och tamkatt. IUCN kategoriserar arten globalt som akut hotad (CR).
Coleeyura schellensis (Сейшельський мішкокрил[джерело?]) — один з видів мішкокрилих кажанів родини Emballonuridae, перебуває на межі зникнення.
Країни поширення: Сейшельські о-ви. Цей вид був записаний у прибережних печерах зі стабільно прохолодною температурою і доступом до рідного пальмового лісу або болотного місця проживання.
Вид чутливий до порушень печер.
Coleeyura schellensis (Сейшельський мішкокрил[джерело?]) — один з видів мішкокрилих кажанів родини Emballonuridae, перебуває на межі зникнення.
Coleura seychellensis là một loài động vật có vú trong họ Dơi bao, bộ Dơi. Loài này được Peters mô tả năm 1868.[2]
Phương tiện liên quan tới Coleura seychellensis tại Wikimedia Commons
Coleura seychellensis là một loài động vật có vú trong họ Dơi bao, bộ Dơi. Loài này được Peters mô tả năm 1868.
Сейшельский мешкокрыл[1] (лат. Coleura seychellensis) — небольшая летучая мышь семейства футлярохвостых, находящаяся на грани исчезновения. Обитает на нескольких из Сейшельских островов.
Маленькая летучая мышь, вес которой едва превышает 10 граммов. Длина предплечья у обследованных экземпляров составляет от 52 до 57 миллиметров. Наблюдения показывали, что мешкокрыл, охотясь, летает зигзагами, как высоко (15—20 м) так и низко (1,5—2 м) над землёй. Его рацион составляют относительно крупные насекомые, скопления которых он отыскивает на разных высотах над уровнем моря. Этому виду для обитания нужны пещеры с горизонтальным потолком и стабильной низкой температурой, при этом важным фактором является отсутствие растительности у входа, обеспечивающее свободный пролёт[2][3].
Исторический ареал вида охватывал как минимум четыре из внутренних Сейшельских островов: Маэ, Силуэт, Праслен и Ла-Диг. Особей с островов Праслен и Маэ выделяют в подвид Coleura seychellensis seychellensis, а с островов Силуэт и Ла-Диг — в подвид Coleura seychellensis silhouettae. На островах Ла-Диг и Праслен, по свидетельствам, вид не встречается с 1980-х годов. Крупнейшая субпопуляция обитает в пещере на острове Силуэт, в ходе наблюдений 2003 года в ней было насчитано 32 особи. В 2008 году, однако, отмечено было всего 27 животных. В 2010 году часть летучих мышей покинула колонию, основав новую; по последним оценкам, в первой насчитывалось от 18 до 40, а во второй от 18 до 22 особей. На Маэ было отмечено три колонии: одна насчитывала приблизительно 27 животных, другая — около восьми, в третьем же месте наблюдались всего одна или две особи[2].
Международный союз охраны природы присвоил виду наивысший охранный статус CR — на грани исчезновения (повышен с EN в 1996 году)[2]. Природоохранный трест Сейшельских островов (англ. Nature Protection Trust of Seychelles) вёл проект по сохранению вида с 1997 по март 2011 года, когда программа была свёрнута в отсутствие правительственной поддержки. В 2012 году вид был включён в перечень из сотни видов, находящихся под наибольшей угрозой исчезновения, в совместной публикации Комиссии по выживанию видов[en] IUCN и Зоологического общества Лондона[4][5].
Вероятно, наиболее катастрофический упадок популяция вида пережила в конце XIX — начале XX века, когда леса активно вырубались под кокосовые плантации. В настоящее время основными угрозами виду является инвазивная лиана Pueraria phaseoloides, которая меняет температурный градиент внутри пещер, если обрастает вход, а также интродуцированная в 1949 году на острова обыкновенная сипуха и дикие кошки[2][3].
Сейшельский мешкокрыл (лат. Coleura seychellensis) — небольшая летучая мышь семейства футлярохвостых, находящаяся на грани исчезновения. Обитает на нескольких из Сейшельских островов.
세이셸대꼬리박쥐(Coleura seychellensis)는 대꼬리박쥐과에 속하는 박쥐의 일종이다. 세이셸의 중부 화강암 섬에서 발견된다. 식충성 박쥐로 숲 개간지에서 밤에 주로 먹이를 구하며, 낮에는 무리를 지어 둥지에서 매달려 지낸다. 이전에는 세이셸 제도 전체에서 풍부한 개체수를 보였지만, 현재는 3개 섬에서만 발견된다. 개체수가 감소하고 있기 때문에 국제 자연 보전 연맹(IUCN)이 멸종위급종으로 분류하고 있다. 농장에서 코코넛을 재배하기 위하여 숲을 개간하고, 외래종 식물이 유입됨에 따라 세이셸대꼬리박쥐의 먹이인 곤충들의 먹이가 감소하기 때문으로 추정된다.
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