Azores noctule (Nyctalus azoreum)

Also known as: Azorean bat
French: Noctule Des Açores
Spanish: Nóctulo De Azores
GenusNyctalus (1)
SizeForearm length: 35 - 42 mm (2)
Weight6 - 15 g (2)

The Azores noctule is classified as Endangered (EN) on the IUCN Red List (1).

The Azores noctule (Nyctalus azoreum) is the only species of mammal endemic to the Azores archipelago, a remote group of islands in the North Atlantic (3). Bats of the Vespertilionidae family are generally small, with tiny eyes and relatively long ears (4) (5).

This species was once believed to be a subspecies of Leisler's bat (Nyctalus leisleri), but it is now known to be genetically distinct (2). The Azores noctule is considerably smaller and has a much darker coat than Leisler's bat (2). It also has an echolocation frequency that is four to five hertz (Hz) higher than that of Leisler's bat (2).

The Azores noctule is endemic to the Azores archipelago, where it occurs on seven of the nine islands; Faial, Pico, San Jorge, Graciosa, Terceira, San Miguel and Santa Maria (1) (2) (6).

This species occurs at elevations of up to 600 metres (1).

The Azores noctule forages and roosts in a range of natural and semi-natural habitats, including forests, rock crevices and buildings (1).

One of the most unique behaviours of the Azores noctule is its frequent habit of flying during the daytime, which is unusual among bats (7). It is, however, most active at night, emerging from its daytime roosts in groups to forage (7). It is often seen feeding on insects around artificial lighting (1).

In spite of popular misconception, bats are not actually blind, with many species having extremely good vision (4). Many species, including the Azores noctule, also use echolocation, emitting high frequency sounds in order to detect prey and create a mental map of their environment (4).

Although there is little information on the reproductive behaviour of the Azores noctule, maternity roosts of this species have been found in buildings, trees and rock crevices (1). The Azores noctule has a gestation period of 70 to 75 days and only a single litter is produced each year (5). Members of the genus Nyctalus generally give birth to one or two young, and the young bats are usually cared for by the female (4) (5).

The main threats to the Azores noctule are thought to be human persecution and destruction of roost sites. This species' habit of flying during the daytime makes it particularly vulnerable to persecution as colonies are easy to locate (1).

The Azores noctule is also currently thought to be threatened by habitat loss and pesticide use, with the invasion of alien plant species having a further detrimental effect on this species’ populations (1).

Although no specific protective legislation exists in the Azores for this species, the Azores noctule is currently listed under the Bern Convention and is included in Annex IV of the EU Habitats and Species Directive, meaning this species is afforded some protection (1) (8) (9).

Future plans for the conservation of the Azores noctule include the protection of its roosts, as well as a public awareness campaign to reduce persecution of this species (1). The restoration of its natural habitat and reduction in use of pesticides are also hoped to be beneficial to the Azores noctule. Further research into the ecology of this species will help to better understand its conservation requirements (1).

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  1. IUCN Red List (October, 2011)
  2. Salgueiro, P., Ruedi, M., Coelho, M.M. and Palmeirim, J.M. (2007) Genetic divergence and phylogeography in the genus Nyctalus (Mammalia, Chiroptera): implications for population history of the insular bat Nyctalus azoreum. Genetica, 130: 169-181.
  3. Salgueiro, P., Palmeirim, J.M., Ruedi, M. and Coelho, M.M. (2008) Gene flow and population structure of the endemic Azorean bat (Nyctalus azoreum) based on microsatellites: implications for conservation. Conservation Genetics, 9: 1163-1171.
  4. Macdonald, D. (2006) The Encyclopedia of Mammals. Oxford University Press, Oxford.
  5. Nowak, R.M. (1999) Walker’s Mammals of the World. The Johns Hopkins University Press, Baltimore.
  6. Salgueiro, P., Palmeirim, J.M., and Coelho, M.M. (2010) Lack of gene flow between the insular bat, Nyctalus azoreum and its mainland ancestor Nyctalus leisleri (Vespertilionidae, Chiroptera): evidence from microsatellites. Folia Zoologica, 59(1): 26-34.
  7.  Irwin, N.R. and Speakman, J.R. (2003) Azorean bats Nyctalus azoreum, cluster as they emerge from roosts, despite the lack of avian predators. Acta Chiropterologica, 52(2): 185-192.
  8. Council of Europe: Bern Convention (October, 2011)
  9. EU Habitats Directive (October, 2011)