Alcathoe bat

Alcathoe bat

Alcathoe bat

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SPECIES
Myotis alcathoe

The Alcathoe bat (Myotis alcathoe ) is a European bat in the genus Myotis. Known only from Greece and Hungary when it was first described in 2001, its known distribution has since expanded to Spain, England, Sweden, and Azerbaijan, among other countries. It is similar to the whiskered bat (Myotis mystacinus ) and other species and is difficult to distinguish from them. However, its brown fur is distinctive and it is clearly different in characters of its karyotype and DNA sequences. Although some genetic data suggest that it is related to Geoffroy's bat (Myotis emarginatus ), other analyses do not support a close relationship between M. alcathoe and any other species.

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With a forearm length of 30.8 to 34.6 mm (1.21 to 1.36 in) and body mass of 3.5 to 5.5 g (0.12 to 0.19 oz), Myotis alcathoe is a small bat. The fur is usually reddish-brown on the upperparts and brown below, but more grayish in juveniles. The tragus (a projection on the inner side of the ear) is short, as is the ear itself, and the inner side of the ear is pale at the base. The wings are brown and the baculum (penis bone) is short and broad. M. alcathoe has a very high-pitched echolocation call, with a frequency that falls from 120 kHz at the beginning of the call to about 43 kHz at the end.

Usually found in old-growth deciduous forest near water, Myotis alcathoe forages high in the canopy and above water and mostly eats flies. The animal roosts in cavities high in trees. Although there are some winter records from caves, it may also spend the winter in tree cavities. Several parasites have been recorded on M. alcathoe. The IUCN Red List assesses Myotis alcathoe as "data deficient", but it is considered threatened in several areas because of its rarity and vulnerability to habitat loss.

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Appearance

Myotis alcathoe is the smallest European Myotis species. The fur is brownish on the upperparts, with a reddish tone in old specimens, and a slightly paler gray-brown below. Younger animals may be completely gray-brown. The brown fur distinguishes adult M. alcathoe from other whiskered bats, but juveniles cannot be unambiguously identified on the basis of morphology. M. alcathoe is similar to Daubenton's bat (Myotis daubentonii ) and M. emarginatus in color. On the upper side of the body, the hairs are 6 to 8 mm long and have dark bases and brown tips. The hairs on the lower side of the body are only slightly paler at the tip than at the base.

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The face and the upper lips are reddish to pink, not dark brown to black as in M. mystacinus. Although most of the face is hairy, the area around the eyes is bare. The nostrils are heart-shaped, and their back end is broad, as in M. brandtii, not narrow as in M. mystacinus. Several glands are present on the muzzle, most prominently in reproductively active males. The ears are brown and are lighter on the inside than the outside. There is a notch at the edge of the ear, and the pointed tragus (a projection inside the ear that is present in some bats) extends up to this notch; the tragus is longer, extending beyond the notch, in both M. brandtii and M. mystacinus. The base of the inner side of the ear is white; it is much darker in M. mystacinus. The feet and the thumbs are very small. The small size of the ear, tragus, feet, and thumb distinguishes M. alcathoe from the slightly larger M. mystacinus and M. brandtii, but the feet are relatively larger than in M. mystacinus.

The wings are brown, but lighter than those of M. mystacinus. The plagiopatagium (the portion of the wing between the last digit and the hindlegs) is attached to the fifth toe. The tail extends only about 1 mm beyond the back margin of the uropatagium (the portion of the wing membrane between the hindlegs). The calcar, a cartilaginous spur supporting the uropatagium, is slender. With a width around 1.3 mm, the penis is narrow, and it lacks a broadened tip (except in one Croatian specimen). The baculum (penis bone) is about 0.5 mm long. The short and broad shape of this bone distinguishes M. alcathoe from M. brandtii as well as M. ikonnikovi.

The skull is similar in shape to that of M. mystacinus and M. brandtii, but the front part of the braincase is higher. The second and third upper premolars (P2 and P3) are tiny and pressed against the upper canine (C1) and fourth premolar (P4). The canine is less well-developed than in M. mystacinus. There is a clear cusp present on the side of the P4. The accessory cusp known as the protoconule is present on each of the upper molars when they are unworn. M. mystacinus lacks the P4 cusp and the protoconules on the molars, but M. brandtii has an even larger cusp on P4.

As usual in Myotis species, M. alcathoe has a karyotype consisting of 44 chromosomes, with the fundamental number of chromosomal arms equal to 52. However, a 1987 study already found that M. alcathoe (then called "Myotis sp. B") differs from both M. mystacinus and M. brandtii in the pattern of active nucleolus organizer regions on the chromosomes. M. alcathoe also differs from other Myotis species in the sequences of the mitochondrial genes 12S rRNA and NADH dehydrogenase subunit 1 by at least 5% and 13%, respectively.

M. alcathoe has the highest-frequency echolocation call of any European Myotis. In open terrain, the call has an average duration of 2.5 ms, but it may be up to 4 ms long. At the beginning, its frequency is around 120 kHz, but it then falls fast, subsequently falls slightly slower, and at the end falls faster again. The call reaches its highest amplitude at around 53 kHz. It terminates at around 43 to 46 kHz; this characteristic is especially distinctive. In different experiments, the time between calls was found to be around 85 and 66 ms, respectively. The high-pitched call may be an adaptation to the animal's occurrence in dense vegetation.

Head and body length is about 4 cm (1.6 in) and wingspan is around 20 cm (7.9 in). Forearm length is 30.8 to 34.6 mm (1.21 to 1.36 in), tibia length is 13.5 to 15.9 mm (0.53 to 0.63 in), hindfoot length is 5.1 to 5.8 mm (0.20 to 0.23 in), and body mass is 3.5 to 5.5 g (0.12 to 0.19 oz).

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Distribution

Geography

Although Myotis alcathoe was initially known only from Greece and Hungary and was thought to be restricted to southeast Europe, records since then have greatly expanded its range, and it is now known from Portugal, Spain and England to Sweden and European Turkey. In several European countries, focused searches were conducted to detect its occurrence. Its habitat generally consists of moist, deciduous, mature forest near streams, for example in ravines or in alluvial forest (forest near a river), where there are many decaying trees that the bat can use as roosting sites. In Germany, its preferred habitat consists of mixed deciduous forest. In the south of the continent, it usually occurs in mountain ranges, but the factors affecting its distribution in the north are less well known. Its range appears to be similar in shape to those of the greater and lesser horseshoe bats (Rhinolophus ferrumequinum and R. hipposideros ) and Myotis emarginatus. It may yet be found in other European countries, such as the Benelux countries, Ireland, and Moldova. Although there are abundant records from some areas, such as France and Hungary, the species appears to be rare in most of its range.

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Known records are as follows:

The species is also known from Montenegro and possibly from Bosnia and Herzegovina. Early records of Myotis ikonnikovi —now known to be an eastern Asian species—from Ukraine, Bulgaria, and Romania may also pertain to this species. Because whiskered bats in many cases cannot easily be distinguished from each other without the use of genetic methods, some listings do not differentiate between them; records of M. alcathoe and/or M. mystacinus and/or (in some cases) M. brandtii have been reported from Bulgaria, Belgium, and Montenegro.

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Alcathoe bat habitat map

Biome

Alcathoe bat habitat map

Habits and Lifestyle

Myotis alcathoe is a rare species with narrow ecological requirements. According to a study in the Czech Republic, the diet of Myotis alcathoe mostly consists of nematoceran flies, but caddisflies, spiders, small lepidopterans, and neuropterans are also taken. The presence of spiders in the diet suggests that the species gleans prey from foliage. It forages mainly high in the canopy and over water, and is often found in dense vegetation. The parasitic mite Spinturnix mystacina has been found on M. alcathoe, and the mites on M. alcathoe, M. brandtii, and M. mystacinus are genetically closely related. The bat fly Basilia mongolensis nudior has been recorded on M. alcathoe in Thuringia and the tick Ixodes vespertilionis in Romania. When caught, individuals of M. alcathoe are much calmer than M. mystacinus or M. brandtii.

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M. alcathoe lives in small groups. In Greece, a maternity colony, containing three females and two juveniles, has been found in a plane tree. Additional roosts were found high in oak trees in Baden-Württemberg and Saxony-Anhalt. Twenty-seven roosting sites have been found in the Czech Republic, all but one in trees (the last was in a concrete pole). Most of the tree roosts were in oaks (Quercus robur ); others were in limes (Tilia cordata ), birches (Betula pendula ), and various other species. Its strong preference for roosting sites in trees is unusual among European bats. Roosts tend to be located high in the canopy, and are often in old trees. In summer, roosts may contain large groups of up to 80 individuals, but autumn roosts in the Czech Republic are occupied by smaller groups. M. alcathoe swarms from late July to mid-September in southern Poland.

In Saxony-Anhalt, the species forages deep in valleys when temperatures are above 10 °C (50 °F), but on warmer slopes or rocky areas when it is colder. There, M. alcathoe is relatively easy to capture in August, because M. brandtii and M. mystacinus already start swarming in late July. Although there are some records of M. alcathoe in caves during the winter, it is also possible that animals spend the winter in tree cavities, and whether swarming behavior occurs in M. alcathoe is unclear. An animal found in a cave in Saxony-Anhalt in January was not sleeping deeply. Reproduction may also take place in caves, but pregnant females have been found as late as June. Relatively many juveniles are caught between July and September. In England, one individual of M. alcathoe was captured in 2003 (and identified at the time as M. brandtii ) and again in 2009. Three individuals that were telemetrically tracked (in eastern France, Thuringia, and Baden-Württemberg, respectively) moved only 800 m (2,600 ft), 935 m (3,068 ft), and 1,440 m (4,720 ft) from their night quarters; M. brandtii and M. mystacinus tend to move over longer distances. A study in Poland suggested frequent hybridization among M. alcathoe, M. brandtii, and M. mystacinus sharing the same swarming sites, probably attributable to male-biased sex ratios (1.7:1 in M. alcathoe ), a polygynous mating system, and the high number of bats at swarming sites. M. alcathoe showed a particularly high proportion of hybrids, perhaps because it occurs at lower densities than the other two species.

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Lifestyle

Mating Habits

Population

Population number

Because Myotis alcathoe remains poorly known, it is assessed as "Data Deficient" on the IUCN Red List. However, it may be endangered because of its narrow ecological preferences. Reservoir construction may threaten the species' habitat in some places; two Greek sites where it has been recorded have already been destroyed. Forest loss is another possible threat, and the species may be restricted to undisturbed habitats. Because of its patchy distribution and likely small population, it probably does not easily colonize new habitats. The species is protected by national and international measures, but the IUCN Red List recommends further research on various aspects of the species as well as efforts to increase public awareness of the animal. In addition, old forests need to be conserved and the species' cave roosts need to be protected.

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In Catalonia, the species is listed as "Endangered" in view of its apparent rarity there. The Red List of Germany's Endangered Vertebrates lists M. alcathoe as "Critically Endangered" as of 2009. In the Genevan region, the species is also listed as "Critically Endangered" as of 2015. In Hungary, where the species is probably not uncommon in suitable habitat, it has been protected since 2005. However, the species is declining there and is threatened by habitat loss and disturbance of caves.

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References

1. Alcathoe bat Wikipedia article - https://en.wikipedia.org/wiki/Alcathoe_bat
2. Alcathoe bat on The IUCN Red List site - https://www.iucnredlist.org/species/136680/518740

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