22.

Nathusius’s Pipistrelle

Pipistrellus nathusii

French: Pipistrelle de Nathusius / German: Rauhautfledermaus / Spanish: Pipistrela de Nathusius

Taxonomy. Vesperugo nathusii Keyserling & Blasius, 1839,

Berlin, Germany.

Pipastrellus nathusii appears to be close to the P. kuhlii complex, which includes paraphyletic P. kuhliiand P. maderensis . Monotypic.

Distribution. Most of Europe (from Ireland and Iberian Peninsula E to Russia and W Kazakhstan), Turkey, and Caucasus; also on Mediterranean Is such as Crete or Mallorca.

Descriptive notes. Head-body 44-54 mm, tail 30-40 mm, ear 10-5-16 mm, forearm 32-2-37-1 mm; weight 6-15-5 g. Fur color of Nathusius’s Pipistrelle changes seasonally, being dark brown or gray brown in winter and reddish in summer. Fur is long and uniformly colored, but venteris slightly paler or more yellowish than dorsum. Proximal one-half of uropatagium is covered by fur. Bare skin is dark brown, snout is short and rounded, and ears are triangular and short, with slender and rounded tragus. Compared with other pipistrelle species, wings of Nathusius’s Pipistrelle are quite long (wingspan 230-250 mm), perfectly adapted for long flights and its migratory behavior. Although not always reliable, a particular wing venation pattern is used as a diagnostic character (cell from elbow to fifth finger clear ly divided). I* is bicuspid, I’ is longer than second cusp of I, canines are considerably large, P? is small but visible above gum, and lower molars are nyctalodont. Chromosomal complement has 2n = 44, FNa = 50, and FN = 54.

Habitat. [Lowland to alpine habitats from sea level up to elevations of ¢. 2200 m in the Alps (probably single vagrant individuals). Habitats selected by Nathusius’s Pipistrelle include woodlands, forest edges, wetlands, open areas, and grasslands. In terms offorests, it occurs in deciduous, lowland, riparian, and coniferous forests and urban gardens with isolated trees. It tends to select those habitats surrounding ponds, lakes, or water bodies; thus,it is common in wetlands, swamps, and floodplains, especially during migration.

Food and Feeding. Nathusius’s Pipistrelle reportedly eats Diptera and Lepidoptera, especially non-biting midges, mosquitoes, and black flies. Despite being slower than its congeners, it hunts insects (aerial hawker) at 3-20 m aboveground, commonly on forest edges, linear structures, and forest paths and over water bodies (from small ponds to large lakes), and occasionally around streetlamps. It has also been recorded foraging over sea up to 1-3 km from the coast. Dietary composition varies between maternity, swarming, and migration periods. In Latvia, during migration, Nathusius’s Pipistrelles seem to use a “fly-and-forage” feeding strategy, which consists in stopping several times during migration to feed and then continue the flight.

Breeding. Mating of Nathusius’s Pipistrelles occurs in June-November, including when they roost in nursery colonies (June-August), during migration (August-November), and at their destination at swarming and hibernation sites (November). Males can be resident in swarming areas (which they defend from other males), visitors to specific mating locations, or sporadic visitors that try to mate opportunistically. Maternity colonies are only found in northern and Eastern Europe (Britain, eastern Germany, Baltic States, Belarus, Ukraine, and Russia). During breeding season, Nathusius’s Pipistrelles congregate in small colonies of some tens to a few hundred individuals, roosting in tree holes, bat boxes, and buildings, usually in lowland forests and wetlands. They tend to give birth to twins in June and leave colonies by the end ofJuly. Young females become sexually active during their first year of life. Nathusius’s Pipistrelles can live up to 13 years.

Activity patterns. Nathusius’s Pipistrelle emerges at dusk to hunt flying insects. Unlike other pipistrelles, its flight is not that erratic, being straighter and more predictable. It roosts in hollow trees, bird and bat boxes, rock crevices, expansion joints in bridges, houses, and a wide range of different buildings, timber claddings, or wooden churches. In winter,it tends to roost in rock crevices, cliffs, caves, mines, and buildings in urban areas (most likely benefiting from urban heat islands). It hibernates from mid-winter to early spring. Its echolocation is very similar to that of Kuhl’s Pipistrelle and has high FM sweeps with CF cue that resembles a hockey stick-shaped call when represented on sonograms. Peak frequencies are ¢.38—43 kHz. Echolocation calls of Nathusius’s Pipistrelle can be confused with those of Kuhl’s Pipistrelle (PF. kuhliz) and Savi’s Pipistrelle ( Hypsugo savii). Calls are variable; in open spaces, FM component can disappear or be lower in frequency, making identification difficult; and in cluttered environments, pulses become highly modulated resembling Myotis echolocation. Pulses last up to 12 milliseconds. Socials calls are very distinct from those of Kuhl’s Pipistrelle and are typically used to reliably identify recorded free-flying bat calls.

Movements, Home range and Social organization. Nathusius’s Pipistrelle is one of the few long-distance migratory bat species in Europe, for which migration patterns of more than 1900 km have been reported. In Europe, it tends to breed in north-eastern countries in summer and migrate toward south-western countries to hibernate. In these regions,it positively selects natural wetlands for foraging and avoids agricultural lands and pastures. During migration, it presumably follows coastlines (it has been captured or recorded in offshore platforms and fishing boats), but it has also been captured over high mountains or following waterways. It has also been recorded migrating from continental Europe to Great Britain. Females start migration before males. Migration extends from August to October or November. Nathusius’s Pipistrelles can fly up to 29-48 km/night and only occasionally up to 80 km /night. During the maternity period, foraging areas are relatively close to maternity colonies (less than 6-5 km). Maternity colonies usually share space with the Common Pipistrelle, Brandt's Myotis ( Myotis brandtii), and the Pond Myotis ( M. dasycneme).

Status and Conservation. Classified as Least Concern on The IUCN Red List. Although not very common, Nathusius’s Pipistrelle is quite widespread. Although it has been more common in northern countries,it is now more frequently reported in the south, and during the last few decades, it has been reported or established in the Netherlands, UK, Switzerland, Italy, and Spain. Because it is one of the few long-distance migratory bat species in Europe, modification or fragmentation of habitat and commuting routes might compromise its movements. Roost disturbance and destruction, loss of mature trees in wetlands, and direct persecution are recognized as direct threats.

Bibliography. Arslan & Zima (2014), Benda, Georgiakakis et al. (2008), Bogdanowicz (1999a), Boshamer & Bekker (2008), Brosset (1990), Dietz & Kiefer (2016), Flaguer, Puig-Montserrat et al. (2009), Flaquer, Ruiz-Jarillo et al. (2005), Harris &Yalden (2008), Jahelkova et al. (2008), Kriiger et al. (2014), Limpens & Schulte (2000), Lundy et al. (2010), Pacifici et al. (2013), Paunovi¢ & Juste (2016), Pétersons (2004), Rodriguez-Munoz et al. (1993), Russ & Racey (2007), Russ, Hutson et al. (2001), Russ, O'Neill & Montgomery (1998), Sachanowicz et al. (2019), Schober & Grimmberger (1998), Speakman et al. (1991), Suba et al. (2012), Trujillo & Garcia (2009), Vierhaus (2004), Voigt et al. (2012).