196.

Eurasian Serotine

Eptesicus serotinus

French: Sérotine commune / German: Eigentliche Breitfligelfledermaus / Spanish: Murciélago hortelano

Other common names: Big Brown Bat, Common Serotine Bat, European Serotine Bat, Serotine Bat, Silky Bat

Taxonomy. Vespertilio serotinus Schreber, 1774,

France.

Eptesicus serotinus previously included E. isabellinus and E. pachyomus . Using mitochondrial and nuclear genes, J. Juste and colleagues in 2013 found that all three species were supported as distinct species, but each type of data found different relationships. Mitochondrial genes showed a paraphyletic E. serotinus, with the nominate form being sister to a clade including E. ogneuvt, the other E. serotinus clade (including subspecies mirza and turcomanus), and E. bottae whereas nuclear genes showed that all three of these taxa represented a single clade, with E. serotinus (including mirza and turcomanus) sister to E. pachyomus and E. isabellinus being sister to this clade. A similar situation was demonstrated by I. V. Artyushin and colleagues in 2018, where nuclear genes supported the traditional view that E. isabellinus and E. pachyomus are included under E. serotinus, but mitochondrial data showed them to be vastly distinct while E. serotinus was paraphyletic. Taxa turcomanus and mirza have sometimes been united as a separate species, but followingJuste and colleagues in 2013 and Artyushin and colleagues in 2012 and 2018, these taxa are included as subspecies of E. serotinus . Artyushin and colleagues in 2012 showed that there is gene flow between E. s. serotinus and E. s. turcomanus, supporting their conspecific status. There is extensive past hybridization between FE. serotinus and E. nilssonii that can make genetic studies difficult to conduct, especially using mitochondrial genes, and a number of genetic studies have found these species to be paraphyletic with one another. A new species, E. lobatus by I. Zagorodniuk in 2009, from Ukraine was recently described based on calcar distinctions (FE. lobatus having well-defined postcalcarial lobe), but this taxon is otherwise extremely similar to E. serotinus and probably represents a variant of the nominate subspecies, which it is synonymized under here. A new subspecies was recently described from Turkey, named FE. s. anatolicus by A. Karatag in 2019, but this name is preoccupied by E. anatolicus by H. Felten in 1971, making anatolicus ajunior homonym ofthe latter and invalidating the name, which is here considered a synonym of E. s. mirza. Exact distributional limits among FE. serotinus and E. pachyomus are still uncertain in Iran, Afghanistan, Pakistan, India, and China. Subspecies currently correspond to three morphotypes detected using morphological data and limited genetic data. Three subspecies recognized.

Subspecies and Distribution.

E.s.serotinusSchreber,1774—muchofEuropeexceptforSIberianPeninsulaandmostofScandinavia,beingfoundinSBritainandfromN&CIberianPeninsulaEtoextremeSScandinavia,SWEuropeanRussia,Caucasus,andN&ETurkeyalongwithnumerousMediterraneanIs(BalearicIs,Corsica,Sardinia,andSicily),includingIonian(Corfu)andAegeanIs(Samothrace,Lesbos,Skyros,Euboea,Samos,Crete,andRhodes).

E.s.mirzadeFilippi,1865—STurkey,WSyria,Lebanon,Israel,andNW,C&SWIran.

E. s. turcomanus Eversmann, 1840 — Central Asia in SC Russia, Kazakhstan, Uzbekistan, Turkmenistan, N Iran, Kyrgyzstan, Tajikistan, N Afghanistan, and NW China (Xinjiang).

Descriptive notes. Head-body 62-82 mm, tail 39-65 mm, ear 14-22 mm, hindfoot 10-18 mm, forearm 48-58 mm; weight 18-25 g. The Eurasian Serotine is robust and considerably larger than its closest relative, the Northern Serotine (E. nilsson). Fur is long, dense, and silky. Dorsal pelage is generally smoky brown, with yellowish tinge (hairs have yellowish tips and dark bases), but can vary from dark brown to almost reddish in some individuals. Ventral pelage is paler, ranging from uniform gray to buffy gray or pale brownish. Bare parts of face, ears, limbs, and membranes are dark brown or blackish. Muzzle is robust and nearly naked, with well-defined glandular swellings on either side, and upper lip is fringed with fine hairs. Ears are moderately tall and subtriangular, with six transverse ridges, strong angular convexity on anterior border below one-half the height, basally convex posterior border (but straight below tip) inserted at base of antitragus, and rounded tips; tragus is less than one-half the ear length, with straight anterior border, gently convex posterior border, distinct notch Just above basal lobe, and bluntly pointed tip. Wings are wide and attached to base of each foot, with wingspan of ¢. 370 mm. Tail extends c¢.3-5 mm past margin of uropatagium, and calcar is well developed, sometimes having well-developed postcalcarial lobe but usually thisis ill defined. Baculum is short (1-1-4 mm long) but longer than in Botta’s Serotine ( E. bottae) and generally Y-shaped, with moderate to deep basal bifurcation, being slightly deflected ventrally at base. Skull is robust; rostrum is broad with lateral concavities; zygomatic arches are widely flared; braincase is ovoid, with prominent flanges in mastoid region; sagittal crest is low but conspicuous; lambdoidal crests are moderately developed; palate is broad compared with Botta’s Serotine and its relatives; tympanic bullae are small; and condylo-basal lengths are 18:5-22 mm. I* is large and broad, with conspicuous secondary cusp; I’ is small, barely exceeding cingulum of I* in height; P* is about one-half the height of C'; M? is reduced; P, is onehalf the crown area and height of P; and lower molars are myotodont. Chromosomal complement has 2n = 50, FNa = 48-50, and FN = 52-54.

Habitat. Semi-desert, shrublands, urban areas (often around streetlamps), agricultural lands (overcattle pasture), forests, wetlands, and high-elevation pastures from sea level up to elevations of c¢. 1440 m. The Eurasian Serotine forages in open areas such as agricultural lands, forest edges, riparian vegetation, parks in human settlements with isolated trees and open spaces, orchards, pastures, and specifically above water bodies, where insect availability tends to be higher.

Food and Feeding. Foraging activity of the Eurasian Serotine is assumed to be more common in forest edges and pastures, tall hedgerows, and open areas with isolated trees, where they mostly feed on Coleoptera supplemented with Lepidoptera, Heteroptera, and Diptera . Eurasian Serotines also eat other arthropods, including Hemiptera, Hymenoptera, Auchenorrhyncha, and Orthoptera . Diet shifts throughout the year based on prey availability. Eurasian Serotines are adapted to fly slowly in open areas,as evident by their wide wings. Typical prey is relatively large arthropods of 5-25 mm in length (e.g. dung beetles, moths, and cockchafers) and is mostly large flying insects. They can hunt in groups of severaltens of individuals in the same location, and these areas are usually situated close to their main roost (4-12 km). Eurasian Serotines are quite opportunistic and therefore flexible in terms of location and prey type, and they can adapt their hunting strategy according to insect availability. Although they are primarily aerial hawkers (capture of prey in flight), they can also capture insects that are resting on vegetation or on the ground (gleaning). In localities close to the ocean, Eurasian Serotines and Northern Serotines have been observed foraging over the ocean where insects are abundant.

Breeding. Maternity colonies of female Eurasian Serotines and their young are formed in May—August. Appropriate internal roost temperature of maternity roosts is ¢.22°C. Mating occurs in autumn (September—October), usually just after the maternity period, and sperm is stored in the females’ reproductive tract over winter. Gestation averages c.52 days. Births usually take place in mid-June. Young start to fly at c.3 weeks of age, are able to forage by themselves after 5-6 weeks, and weaned after 6-7 weeks. Littersize is usually one (twins are rare). Females become sexually active between their first and second year. Oldest known individual was 19-5 years old.

Activity patterns. Eurasian Serotines roost by day in a variety of places, such as cracks and crevices in cliffs, walls, and buildings and occasionally caves, typically found near entrances. Maternity colonies are mainly found in buildings (large unused cavities and also spaces behind cladding) but also hollow trees and rockfissures on occasion. Eurasian Serotines emerge c.20 minutes after sunset; emergence time is adjusted seasonally to moonlight conditions and can be altered by predation risk and poor weather. Activity is unimodal (peak at dusk) in spring and autumn and clearly bimodal (peaks at dusk and dawn) during lactation. Eurasian Serotines can visit up to ten different hunting sites per night and are relatively easy to identify at night by their slow but agile and highly maneuverable flight, with brief glides. It can fly up to 30 m high in a wide variety of habitats. It tends to commute from site to site using the fastest routes, following forest edges or hedgerows probably to increase commuting speed (normally at heights of 10-15 m). Search-call shape is FM/QCEF, with peak frequencies of generally 23-44 kHz. In Britain, average start frequency was 61-5 kHz, end frequency was 28-3 kHz, peak frequency was 33-7 kHz, and duration was 6-7 milliseconds. Recordings in Iran had start frequencies of 35-4-39-1 kHz, end frequencies of 23-9-25-3 kHz, peak frequencies of 25-5-30 kHz, durations of 7-2-12-4 milliseconds, and interpulse intervals of 83-3-246-5 milliseconds. Spanish recordings had maximum frequencies of 28-5-60 kHz, end frequencies of 19-24-5 kHz, peak frequencies of 22.7-28.8 kHz, durations of 5-16-3 milliseconds, and interpulse intervals of 96-:8-291 milliseconds. In general, echolocation of the Eurasian Serotine differs from other similar calls of sympatric species because ofits irregularity and lack of rhythm. Nevertheless, due to the large overlap in frequencies, the Eurasian Serotine tends to be classified in phonic groups containing several species with similar echolocation calls (e.g. Nyctalus spp.).

Movements, Home range and Social organization. The Eurasian Serotine is generally considered sedentary, and longest recorded movement is ¢. 330 km. Nevertheless, even though it is mostly sedentary, there is considerably high gene flow across continental Europe, suggesting a high dispersal rate. It generally roosts alone outside of the reproductive season in winter. Maternity colonies in the breeding season generally have 10-60 individuals, but colonies of up to 300 individuals have been reported. The Eurasian Serotine rarely switches roosts during the breeding season, switching roosts more often outside the breeding season. Males usually roost alone or in small groups of up to 20 individuals. Distances between summer and winter roosts are not well studied, but maximum reported distances between roosts were ¢. 50 km. In Britain, individual home ranges were 0-16 —47-6 km?. Eurasian Serotines either remain in roofs, cliffs, or cavities in building walls for the entire year or move to unknown winter roosts nearby. They occasionally share roosts with the Common Pipistrelle ( Pipistrellus pipistrellus) or the Brown Long-eared Bat ( Plecotus auritus).

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Eurasian Serotine is very common throughout its distribution and considered abundant locally and regionally. In some areas,its populations seem to be increasing (Denmark), but in others, they are decreasing (Britain, Austria, and the Pannonian Basin). In Austria, due to the general decrease in numbers (70%), it has disappeared from lowlands in the eastern of the country. Major threats include roost disturbance, habitat loss and fragmentation, and eventual decrease in insect availability in certain areas due to massive insect control protocols.

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