Bats ;
Seychelles Sheath-Tailed Bat / New Zealand Lesser Short-Tailed Bat
Class: Mammals
Order: Chiroptera
Latin name(s):
Coleura Seychellensis / Mystacina tuberculata
Range: Seychelles (Islands) / New Zealand
IUCN Status: CR / VU ; Cites: - / -
(a 2008 situation).
“The bat is an intermediate animal between bird and mouse, so that it can be called a flying mouse; although it can be classed neither as a bird nor a mouse for it has the appearance of both.” - Konrad Gessner (1516-1565) , (fom Schrober-Grimmberger, p. 11)
This early interpretation, often cited as funny and completely misleading from the bats place and origins in the nature well describes their 'oddities' as animal group. Among mammalians they represent a special case from variety of reasons: They are the sole mammals that can fly. Microbats (Microchiroptera) also use echolocation (or echo-sound) in that flight and for hunting of their prey. As well, the bats have remained largely unchanged from their earliest proven ancestral origin as species, that according to fossil record (and as such, cautious estimate) dates back over 50 million years to the past. Not less meaningful, bats being mainly creatures of the night, they have been (/still are) often associated with forces of evil and other dark origins in general, which may have caused their direct persecution, even. This text, of course, mostly focuses on the preceding aspects and bats in general, but we're not ignoring the human-bat relationships completely.
However trivial in this case, my own first memory from bats dates back for the early childhood, and is from the cabin site situated near small pond where our family used to spend the summer holidays. Sometime, at the age of 5 or less I recollect having seen there bats in the morning light, hanging from the cabin logs with their hind legs, as bats usually do. Since that, (like most people, perhaps) I've rarely seen bats. (My kids probably haven't even encountered one outside animal park/zoo, which makes me sometimes think that memory as example from the shifting baseline; but, on the other hand this can only hold an experience in the life of typical urbanized individual, and also it may originate from the fact that bats are seen most active only in hours after the sunset/preceding sunrise.) Also, as they are easily disturbed and careful fliers, mostly they avoid human watcher – a typical glimpse from bat hunting in the night sky is seen somewhere closer to edge of eye-sight.
Perhaps because these creatures have specialized on night-flight(/and most birds, contrary to bats are active in the day-time) bats in during their evolution are found diversified for surprising large variety of species. In fact, the number of different bat species makes it reasonable to say every 4th or 5th mammal being a flying one. Usually bats worldwide are estimated to contain around 1000 different species. Some are very common, but many are having only very limited habitat, fx some species are restricted to certain cave(s). Traditional scientific view has divided bats for the mentioned microbats and megabats (Megachiroptera). First mentioned are more numerous presenting about well over 700 species, rest consists from megabats1. Megabats - to the contrary - are almost with no exception, herbivorous fruit-eaters and only appear on tropical regions. Microbats usually prefer insectivorous diet.
In addition to that, there's few species having adapted for day-light, like African Yellow-Winged bat (Lavia frons);(strangely, more specific information wasn't available, but likely they have pretty common range...), although that's exceptional. And - almost like to better represent bats diversity as animal group we also find some examples more differing in their diets. In addition to more common insectivorous and fruit-eating species there's few specialized carnivorous bats like the (Australian) False vampire/ the Ghost bat (Macroderma gigas, VU) and Mexican Fish-eating species(Myotis vives, VU) - the fishing bats are further divided for few subspecies. In overall, these still represent exceptional cases.
The peculiar look of various bats, perhaps, and their preferred time of hunting their prey at night has often caused bats associatioted with evil forces (in the past); That so, not just in the christian mythology, but also in some other religions. - And besides, there's that common identification with the good old count Dracula and his companions better known from the books and flicks. But, in reality only few bat species sustain with blood, although the (real) vampire-bats (like Desmodus rotundus) do so (but not the manner of that popular imaginery, and the amount it feeds also is very minimal. Also it rarely occur to 'err' for humans. More harmfully, they are also known to spread some diseases.) Since most naturalists/biologists tend to despise those vampire stories as prejudices and misbeliefs, more usual in the popular imagination, we'll restrain from those in this context (however exiting these are from the fictional view, real bats resemble those as little as they have in common with the Batman – or, alternatively his competitor in the super heroic deeds, Bat girl, less sinister from character moods and doings.) However, it is also often noticed that the bats can look quite frightening, especially when opening their mouth for echolocating.
Nevertheless, the cultural beliefs are rather various and interesting, not the least because bats from evolutionary origin are relatively little known (we'll return to that after few sentences). From the christian imaginery a common motive is the devils painted with bat wings, but also fx some African tribes connect the bat for the witchcraft. Ancient Mayas depicted bat as deity symbolizing 'the underworld', according to hieroglyphs where bat frequently apears. To the contrary - in Chinese and Japan imaginery bats have always been presented as symbols of happiness. Fx, a common ornamental design/talisman from 18th century China represents tree as symbol of life surrounded by five bat figures as concepts of health, wealth, happiness, longevity and peaceful death. As well, in some European heraldry the bat-motive has been in use for the centuries, fx it is found in form of the coat-of-arms from the city Valencia, Spain (Scrober-Grimmberger, p. 9-10) (and perhaps transferred from that to the emblems in football heraldry, in the cases of Valencia CF and FC Barcelona). In many native American tales bat represents a trickster spirit (but, so do some other animals).
And, again to the contrary (perhaps little more irrelevant, but nevertheless mentioned) – many bat species favor/inhabit the old churches buildings, simply from the reason that those by architecture contain holes and hides that bats can use for the resting, winter hibernating, etc. So, quite the opposite to that 'traditional' or popular view, they are found quietly respecting the peacefulness of the church buildings and instead are active mostly during the night hours.
Besides the claims from bats dark origins (that probably partly resulting from their strange looks), also classification of bats was found difficult in the early times of natural history. Already in the beginning was noted that 16th century naturalist and bibliographer (Gessner) who classified them in the same genera with mices. This conception has remained for the later times fx in the naming of the Greater mouse-eared bat (Myotis myotis). Also the Swedish biologist Carl Linnaeus (1707-1778), creator of the animal classification, faced similar problems in classifying bat and first placed it in his Systema Naturae (1735) among the predatory animals. Some 30 years later he changed the view, and on the basis of the outer characteristics (existence of mammalian teats) classified it for the same clan as the apes.(Schrober-Grimmberger, p. 11) Since that, from the morphological characteristics bats were placed in the group that also contains primates, tree shrews, flying lemurs.
However, more recent knowledge, according to DNA notices Chiroptera more closely related for the other early branches of mammalian families, the 'eulipotyphlan insectivores'. Included in the same group as bats are some of the most ancient mammalian species like moles and shrews. (Noticeably, mentioned is the shrews being capable for echolocation as are also the microbats). Also, according the molecular studies it has been supposed, flight and (laryngeal) echolocation in bats having evolved during some 25 million years time, latter sometimes presumed for the period between 83 to 58 million years in the past - These capabilities (echolocation, flight), on that basis are believed to have evolved before the appearance of most recent common ancestor for living and known earliest bats from fossil taxa.(“Integrated fossil...”, 2001) However, the oldest fossils [at least according the information that appeared available for us in MSW when searched] are only known from behind about some 50 million years. So it seems occasionally have been reasoned quite possible that perhaps the flight developed first, (that being the most recent belief, likely). But, in this context we can only notice that bats evolution has been and likely still is a field of rather controversial views, so we're not going further on theories from their earliest origins.
Anyway, it is stated that quite likely that distant (common) ancestor of the extant bats and the foregone species known only from fossils (fx Icaronycterix, Archaeonycteris, Palaeochiropteryx) was a bat with (laryngeal) echolocation and in the megabats (which probably later evolved from the microbats) this feature was lost in some later period (“Integrated fossil...”, 2001). As these various bats are known suddenly appearing in the fossil data at the early Eocene (ca mentioned 50 Mya in the past, fossils found fx from the Wyoming and Paris basin), it is also interesting to notice that early bats - in their primitive but largely similar features to those found in the extant ones - already were relatively diversified in flight capabilities. Fx, Icaronycteris and Archaeonycteris present species with non-specialized flight, that likely were accustomed for the open spaces. To the contrary, Palaeochiropteryx was smaller species and possibly capabilities of flight closer to the ground (this is also considered proposing it was fx preying insects just above the waters) (Agosti-Anton, 2002, p. 32-33). From the bit later period (about some tens of millions years later) in the Miocene prehistoric fossil record, similar specialization in between the ancient bat species is found, fx in their species wing proportions. Early Miocene bat (T. stehlini) likely was species adapted to high altitude and high-speed flight, and also it with most likehood emitted ultrasounds through open mouth during its flight (ie laryngeal echolocation). For comparison there's another species, a Miocene bat which was more adapted to flight at lower heights, Hipposideros bouziguensis, but it appears also to resemble the modern leaf-nosed bats in some other features too (having had similar hollow nasal area in the skull., where the leaflike nose appendages would have fitted. Also it had other features resembling modern bats, fx the hind limbs permitting hanging free during rest). So, it seems/appears mentioned that well-preserved fossils from this species clearly shows similarities in structure to the extant leaf-nosed bats (Agosti-Anton, 2002, p. 100-103). Because these morphological features (in bats skull) are believed to have served the purpose to focus and concentrate the sound waves emitted from bats nostrils, it would seem very likely that also such echolocation cababilities were well developed in some bats at that time already. Also, the extant (leaf-nosed) bat species usually have sharper echolocation (fx, they the have capability to detect thinner wires or ropes when in flight.) So - on the basis of this information available us - sharper echolocation perhaps would have developed on some of these bats (in their preferred lower flying habitat) from the need of more agile sensing of obstacles. Also, it could have evolved parallel with the development of their wings for specialized flight, even though our conclusions are only reasoned on the basis of limited information and general assumed views , perhaps.
Leaving these evolutionary histories aside that likely appear (for us here) a bit too complex in these brief conclusions; and we can instead mention a popular anecdote relating to bat echolocation - or, how this capability for ultrasounds first was found (not yet fully recognized and understood at the time) - the honour can be pointed for the 'unprejudiced' 18th century bishop, mathematician and naturalist Lazaro Spallanzani (1729-1799). Spallanzani first 'proved' experimentally that bats don't need vision for their navigation. That he did by covering the eyes from several bats and then letting them fly around in the dark at the attic. For attic ceilings he had tied some wires that contained bells. To Spallanzani's surprise the "blinded" bats didn't ring those bells, but when their ears were covered this of course happened (as the bats, deprived of their sixth sense, echolation, inevitably flew to the wires) – But, with the highest credibility this likely was not the origin for the common English saying "Bats in the attic".
Complete understanding from bat echolocation developed only some 150 years later, after the invention of sonar in early 20th century. Until that (or close to) it was believed that bats navigated with their sharp night-vision (which has given grounds for the use of bat wings and other body-parts in all kinds of magic potions/witches brews and healing juices or other such practices that seem equally harmful misconception). In the same instance – for the fun of it - we can also be reminded from an another misleading saying; "Blind as bat", which also in fact is double wrong, as the bats eyes are in fact adapted for both daytime and night-vision. They have similarities in their vision to other mammals (bats do have dichromatic colour vision, they have something called rod receptors needed in the night vision and cone receptors for daylight, and even have sense of some UV-light, or about so). (Perhaps there's more variability in between the species in that, as the source appears to mention research carried on the study of some flower visiting species of bat.) Anyway, usually the microbats are merely believed to rely on their echolocation sense, but do need their (night) vision fx when leaving or arriving their roosting sites (and therefore, naturally their vision is better adjusted for that nightly condition).
Many microbats, especially the ones that inhabit the colder hemispheres often are found to hibernate - this being from the reason that they are forced to pass over winter times by some way since inwinter there's not enough prey (insects) available. Bats can control their body temperature, and often they pass over the winter time by 'reducing their thermometer' (lessens the amount of energy needed during that time). In the case of bats this includes lot of variation, fx each species has a particular temperature and the site chosen for hibernation; also, all bats need rather high conditions of humidity in the place of their hibernaculum to prevent dehydration – which often causes hibernating bats being covered by drops of dew (Schrober-Grimmberger, p. 57-59). (Adjacent pic from hibernating bat, Myotis daubentoni.)
Differing from many other mammalians that hibernate, bats even sometimes wake up (and move, eat, etc) occasionally during that time, but a hibernating bat shouldn't be disturbed ; Regaining their normal body temperature takes about 30-60 minutes and the lower the animals energy reserves are, the longer that wakening process will be. (Ibid., p. 63-64). The hibernation periods can vary a lot and they can last from few days to several months. In the colder regions they less commonly are adjusted for to wake up during the colder period, since there's no prey available. Of course all this also causes a lot stress for bats physical strength. In bad weather conditions many new-born die, but also even during the normal winters (youngest bats usually) survival is in the highest risk. Also, many species are found to hibernate in groups.
On the basis that the bats don't fall for complete uninterrupted 'sleep' through the cold season, it would seem like they wouldn't be as vulnerable for the Climate Change effect as some other small mammalians that hibernate – but, without better knowledge and not having with this kind of scheduel any reliable information searched for – we'll forced to leave that question open in this text. In any case the bats seek for their hibernation places where temperatures and relative humidity in the air are stable enough (largely reason for the popularity of caves in that, likely). Some species, similar to birds and butterflies, also migrate, often for distances over 1000 km. Migrating doesn't prevent the bats from also hibernating.
After these various bat details and stories, some words next devoted for the Megachiroptera, or, specifically the Pteropus group, which consist from the bats usually called as flying foxes (name originates from their usual looks, snout resembling that of the fox – but many of the species also have large wingpans). They mainly appear on tropical regions, being widespread in the South-East Asian rainforests mostly, but elsewhere too. Instead of echolocation these bats have other highly developed senses, fx the sense of smell and especially the vision. Many of these bats visits flowers in search of their nectar and other juices, for which purpose they probably have developed advanced UV-vision (and with that they better can locate fx the plants they frequently visits for nutrition). The feeding preferences of these bats also give them an important role in the spreading of various forest plants; Bats eat fruits and spit the seeds out, which is effective mechanism in the seeds dispersion. Some bats fly large distances in search of the food, even about 30 km (or more). Also some, usually smaller species, are important agents of pollination for the forest plants similarly as some birds during day-time. The flowers they visit usually are cream-white from colour and do have smell of mysk; the bats carry pollen that clings in their fur from one flower to an another. Plants/trees that rely on bat pollination include various rain forest species. (pic ; a Fruit bat feeding)
In spite of the large number of species in their family tree - there's 175 at least (and the Pteropodidae, in addition to flying foxes, includes variety of fruit eating bats or even some with more varying diets). But many from them have become threatened. Fx in Malaysia (and various adjacent countries) they are found endangered, but also many flying foxes that have ranges limited to (some) islands/pelagic have been in decline. We can here briefly pick a list – purely random choices - from some better-known species ; threatened species from (tropical) islands include Samoa Flying-fox (Pteropus samoensis, NT), Ryukyu Flying fox (Pteropus dasymallus, NT), Comoro Black Flying-fox (Pteropus Livingstonii, CR) [Surprisingly a search by name of species didn't return us much usable summaries from species mentioned, but anyway...]. As these better known ones only cover species from which rather lot data has been collected, they mainly represent larger frugivorous bats. But there's also less common and smaller species, endangered and also some believed extinct. The usual threats nowadays concerning the bats of the tropical region are most usually habitat destruction, most common being the deforestation and conversion of forests to agricultural purposes (fx it was in some instance mentioned from the Philippines original old-growth forest cover about 90 per cent been lost) ; as well the hunting of animals, and increase of human settlements on their habitat are mentioned as main reasons for the on-going decline. In most of these countries, though, the variety of existing species is rather more diverse than in some other parts of the world, but fx from the mentioned Philippines also number of other very particular animal species are found endangered. Often that also appears as result from the habitat fragmentation.
The first selected species here, Seychelles Sheath-tailed bat (Coleura Seychellensis) is from the smaller bats, from which many are endemic to certain islands. The species is currently found on only one island (Seychelles being an archipelago, consisting from group of smaller islands) – it used to be numerous in the past, and still in 1980s had populations on few more small islands close by. Nowadays they're estimated to consist from lot smaller population than around that 250 mature individuals, which (ao) can make that few enough to cause species classified as Critically Endangered. For their dietary habitats these microbats require availability of diverse, natural forest which can support abundant insects, especially moths and beetles. Therefore, the destruction of their original habitat coastal lowland forest being cleared, likely has been the main reason for their decline. Also, other possible threats mentioned affecting for that are fx the introduced Barn owls and feral cats. Invasive plants also, having reduced the availability of their beetle prey, etc. As for the better and for more information, according to Edge's listing (mammals list) there's conservation efforts carried on the Seychelles Sheath-Tailed bat (not the case being so on every threatened bat species, but perhaps in this case might have prevented the complete disappearance).
Our second exemplary species is also islander. More precisely the New Zealand Lesser Short-Tailed bat (Mysticina tuberculatis) which also is one from only two endemic mammalians found on New Zealands nature, the other one being also bat (/or that was the larger Mysticidae species, M. robusta, which still existed around the mid last century but is now believed extinct). Mysticidae bats appear in some ways exceptional, since the surviving bat is also one from only two bats in the world that do maintain movement and hunt for prey on the forest ground (It spends almost half of its active time as ground-dweller). The other 'walking bat' is the Vampire bat, (Desmodus rotundus) , found only in parts of South-American continent.
The (Mysticidae) bats likely evolved in Australian nature from where a resembling fossil is known (Icarops) and the species mentioned is therefore likely very ancient. The terrestrial movement of the Lesser Short-Tailed bat also has been suggested as the reason for its diet including broader range of foods than any other bat. It eats nectar, flowers and fruit, also various terrestrial invertebrates, fx spiders. However, terrestriality is not believed to have evolved as result from New Zealand lacking (mammalian) predatory species , since mystacinidaes are believed to have existed even before their arrival for the New Zealand nature (time of arrival is of course known from only fossil founds). Preceding that, in the Australia's prehistoric nature these bats (likely) co-existed with the various (nocturnal) predators – including (ao) various marsupial carnivores, carnivorous/omnivorous kangaroos, predatory bats (megadermatidae) (Bird and reptile predators also mentioned in that article). In New Zealand forests the species, also, is believed to have appeared abundant preceding human arrival and diminished as consequence from the original forests been largely reduced. (As well, number of alien mammals having become established, which has been during about 750 years). Disappearance of suitable wet cooler rainforest habitat is believed as the likely reason for the Australian mystacidae species gone extinct sometime during earlier prehistory at least about 10 Mya (= Million years ago), that having caused also various other mammalian species loss as result of climate changes (in during) from early- to mid- Miocene. (“Bats That Walk”, 2009). Mysticidaes, here presented, lasted for the current days only because the species had become established in NZ nature preceding that.
But, likely the interested reader may find more information/also other studies from it than the source we're referring ;(there also is stated fx that “Rather, it would seem that walking is rare in bats because it has advantages for them only in special circumstances.[…], the rich rainforest environment in which the ancestors of the mystiacinid bats evolved in ancient Australia was teeming with ground-based competitors and predators.”) And, this would perhaps give also much grounds for various speculations about bat evolution... but again we'll have to leave that for the mention, since according to known it merely represents an exception for the general rule.
These few particular species briefly presented only show the multitude of bat species in existence, and – on the other hand – similarly their decline largely also converges with the loss of ancient forests and their eco-systems. Like the preceding species various bats have ancestral past and also it truely is so (we can be reminded that) the bats have remained largely unchanged through their evolutionary prehistory. They are therefore often mentioned holding some noteworthy clues from those evolutionary pasts But, likewise we've noticed from all of this, they also have important place in the ecology, especially as particular nocturnal (group of) species.
All this kind of brings us again for that shifting baseline2. , mentioned in early paragraphs of this text. In the northern hemisphere where disappearance of those original 'old-growth' forests happened in somewhat earlier times, some bat species were still in the recent times found 'regular' inhabitants in the human buildings during these recent historical times (fx in those attics). Modern construction techniques and the spread of urban environments – to the contrary - have largely reduced these favored old buildings (the old churches present important exceptions, as was also noticed). On the other hand there's species living in the ceilings of city buildings and as well the largest European bat 'hibernaculum' is in Poland (Nietoperek) where they live (in tens of thousands) at the large concrete tunnel habitats, human built during the Second World War. Nevertheless the bats of the northern hemisphere are found species needed protected, in most countries. Already from that couple decades old Schrober-Grimmberger book (Guide to Bats ,1989), we find bats mentioned in noticeable decline because of the modern developments (; particularly noticed are the reduction of their food sources by use of pesticides and the increased poison levels in bats as other result from that. Also, the destruction of their natural landscapes and habitats, demolization/destruction of roost sites, as well as the unfavourable weather conditions in form of the longer cold and wet spells in during spring and summer times)(Schrober-Grimmberger, p 73-74). In conclusion, bats are nightly mammals and there's about mentioned thousand differing species in existence worldwide. Also, as noticed they show great adaptivity for very different environments and even human built structures. But - to the contrary of some still very abundant species - there's larger number of the threatened.
From the same reasons, I notice my own early memoirs actually presenting a lucky coincidence; It appears a rare 'knot' and joining point in the two different paths, separated by that shifting baseline. Or, in other words, could have been an exceptional random coincidence that sometimes breaks that 'uniform amnesia' in the current (prevailing) form of culture, that creeps everywhere within the process christened with the term 'urbanization'. To the contrary - they say it can sometimes be stopped, or at least slowed down. And also - the bats in these sentences were found culturally very important animals. Simply from the reason they are of help to memorize past things (not the least my own memoirs).
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(Main) sources (&) Studies Referred in the Text/Links:
Agusti-Anton : Mammoths, Sabertooths and Hominids : 65 million years of mammalian evolution in Europe. (2002)
"Bat Eyes Have Ultraviolet-Sensitive Cone Photoreceptors". PLoS ONE, 4(7): e6390. DOI: 10.1371/journal.pone.006390 [Muller B., et al.]
“Bats that walk” BMC Evolutionary Biology, 20 July 2009; 9:169 DOI: 10.1186/1471-2148-9-169 [Hand, SJ, et al.]
Gerlach, J., Mickleburgh, S., Hutson, A.M. & Bergmans, W (2008), Coleura seychellensis. IUCN 2009. IUCN Red List of Threatened Species. Version 2009.1. <www.iucnredlist.org>. (Viewed 03.9.2009.)
“Integrated fossil and molecular data reconstruct bat echolocation” (2001) (PNAS, doi 10/1073, PNAS 2001, 6241-6246) [Springer, et al.]
"Evidence for shifting baseline syndrome" Cons. Stories ; 2009. [Papworth, SK, et al.]
Schrober-Grimmberger, A Guide to Bats of Britain and Europe (1989) [English transl., copy: the MSW library]
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Notes:
1. Various (molecular-, DNA-) studies, also one referred here, make arguments on behalf of more complex division than this traditional one. Fx, it seems proposed to including False Vampire bats (Megadermatidae) and some other bats in the larger main order (Rhinolophoidea) at Megachiroptera , as well Sheath-tailed/Sac winged bats also placed in the Megabats lineage. (The rest of bat families merely belonging for their traditional placing in classification.) Since the purposes of this text are rather more various, we can leave these for the mention and likely these (classifications) still appear little changing in time.
2. And, no matter how related to that (or even not at all), anyway, we also find few more interesting sentences to mention from that European bat guide – a book we've been referring a lot in the preceding text - since there reads: "[...] the fact that different bat species start to emerge at different times is reflected in the old literature, even in the naming of the bats. The noctule, for instance, was called the 'early flying-bat' whilst the serotine was referred to as the 'late-flying bat'.” (Schrober-Grimmberger 1989, p. 31) Perhaps not quite that exiting in the variety of bat phrases and terms, but yet interesting and actually I think it quite well combines these cultural histories from bats and thoughts presented in few concise words (from this point-of-view.)
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Photos: Schrober- Grimmberger , 1989, by E. Grimmberger (Drawing: T. Schneehagen). Fruit Bat from Gamlin-Rohan, 1996, Mysteries of the rain forest by Fogden, M. & P.
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