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Meridional Serotine | Cnephaeus isabellinus
Cnephaeus isabellinus | Cnephaeus isabellinus
Cnephaeus isabellinus, the Meridional Serotine, is the serotine of the southern Iberian Peninsula and North Africa. Temminck described it in 1840 as Vespertilio isabellinus from the surroundings of Tripoli; for a long time it was treated as a subspecies of the Eurasian Serotine (Eptesicus serotinus), until genetic studies of Iberian and North African bats (including Juste and colleagues, 2013) separated it as a distinct species. Since 2023 it has been placed, with the other Old World species of Eptesicus, in the genus Cnephaeus. It therefore appears in the literature under three names: E. serotinus (before the split), E. isabellinus and C. isabellinus. Forearm 44 to 54 mm, weight 15 to 27 grams.
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Tracks
The species roosts in rock crevices, hollow trees, bridges and buildings, rarely in caves, mines or other underground sites. Unlike the Eurasian Serotine, summer and winter roosts are often the same place, and some roosts are used all year. Droppings with beetle remains lie below the entrance of a maternity colony. During the mating season, August to October, males give social calls from their roosts. On a bat detector the species sounds like an irregular series of calls around 25 to 30 kHz.
Identification
A large serotine-type bat with broad wings and a slow, agile flight. The dorsal fur varies from pale yellowish brown with a creamy sheen to almost golden; the underparts are paler, without a clear demarcation from the back. Muzzle, cheeks, ears and membranes are dark brown. The ears are triangular and broadly rounded, with five transverse folds; the tragus is about a third of the ear length, with a blunt tip. The tail projects 2 to 3 mm beyond the tail membrane. Females are slightly larger than males. Search calls are highly variable, frequency-modulated with a near-constant end (FM/QCF): in Morocco the peak frequency was 25.8 to 28.3 kHz (mean 26.9 kHz), in Tunisia 21.7 to 30.3 kHz, in Spain 23.4 to 35.8 kHz.
Similar species
This species cannot be reliably separated from the Eurasian Serotine (Cnephaeus serotinus) in the field: measurements overlap, the fur is paler and yellower on average but varies in both, and according to the handbook the calls cannot be told apart. In southern Spain and Portugal and in North Africa locality decides; in the transition zone in the centre of the Iberian Peninsula genetic analysis is needed. In the hand the species differ in details of the skull, teeth and baculum that are assessed only by specialists. The Common Noctule (Nyctalus noctula) and Greater Noctule (N. lasiopterus) have narrow, pointed wings and a fast flight; their calls overlap in frequency with those of C. isabellinus, so that recordings are confused with Nyctalus in some areas.
Habitat
A wide range of habitats, from semi-desert to Mediterranean woodland and scrub, open farmland, dehesa and urban gardens, from sea level to about 1800 m. The species often forages near water or in places with high humidity, such as riverbanks with dense vegetation. In the north of the African part of the range it also occurs in dense oases in desert and semi-desert. Foraging areas usually lie close to the roost.
Where the animal is most at home, classified with EUNIS — the European standard for habitats.
Distribution
Two subspecies. C. i. boscai lives in southern Portugal and Spain, northern and central Morocco, north-western Algeria and on Lanzarote (Canary Islands); C. i. isabellinus in north-eastern Algeria, Tunisia and north-western Libya. The Strait of Gibraltar is not a barrier for the species: European and African populations exchange genes. Further north on the Iberian Peninsula it is replaced by the Eurasian Serotine. Older literature on the Eurasian Serotine in southern Spain, Portugal and the Maghreb in fact refers to this species.
Way of life
The diet consists mainly of beetles, moths and flies; in a semi-arid urban landscape in southern Spain scarab beetles (Scarabaeidae) and flies made up most of it, with strong seasonal variation. In Libya faecal samples contained mainly ants and beetles. The species hunts in the air but occasionally takes prey from the ground or vegetation. Outside the breeding season the bats live largely alone; males almost always. After hibernation females form maternity colonies of tens to hundreds of animals in late April and early May; the young are born in late May and early June, often as twins. Lactation lasts until mid-August, after which the colonies break up. Females are strongly philopatric; all known movements are under 40 km and are made mainly by males. Hibernation lasts from late October to March in some areas; in Tunisia the species appears to be active all year.
Where and when to look
In Andalusia and the Algarve this is the serotine seen on summer evenings around streetlamps in villages, over rivers and along woodland edges. A maternity colony in a building or under a bridge can be counted at emergence, shortly after sunset. A record by detector or sight can be noted as Cnephaeus sp.; assignment to this species rests on locality, and in central Spain and Portugal on DNA alone.
Conservation status
Least Concern (LC, 2016). The species is locally common, for example in southern Spain, Morocco and northern Algeria. In farmland the bats are suspected of accumulating contaminants through their diet. In Europe the species, as part of the Eurasian Serotine in the old sense, is listed in Annex IV of the Habitats Directive and is covered by the Bern Convention and the EUROBATS Agreement.
Scientific name
Cnephaeus isabellinus | (Temminck, 1840)
Temminck described the species in 1840 as Vespertilio isabellinus; because it was later moved to another genus, the author and year stand in brackets. Cnephaeus is Greek, from knephaios, 'dark, of the twilight', from knephas, 'dusk'; Kaup coined it in 1829, and it has only recently come back into use. isabellinus means 'isabelline', a pale greyish yellow, after the light desert coat. Where that colour name comes from is disputed; the story of a Spanish infanta's shift left unwashed for three years is younger than the word itself. The specimen the first description was based on came from Libya.