Azores noctule
Nyctalus azoreum (Thomas, 1901)
Vespertilionidae
Vulnerable
| Other names | |
|---|---|
| Catalan | Nòctul de les Açores |
| Spanish | Nóctulo de Azores |
| English | Azores noctule |
| French | Noctule des Açores |
| Basque | Gau-saguzar azoretar |
| Galician | Nóctulo das Azores |
Description
Similar in appearance to the Leisler's bat (Nyctalus leisleri), the Azores Noctule is smaller and has a darker coloration. The forearm length of the Azores Noctule ranges between 35 and 40 mm, and its weight varies between 13 and 14.2 g, not overlapping with the larger measurements of the Leisler's bat.
Distribution
The Azores noctule is endemic to the archipelago and is found on the islands of Faial, Pico, São Jorge, Graciosa, Terceira, São Miguel, and Santa Maria. It has not been found on Flores or Corvo, the more isolated islands of the Azores.
Roosts and phenology
Most maternity colonies are found in tree cavities, buildings, and rock crevices and consist exclusively of females, with males being solitary. These maternity colonies are formed in April and can last until September-October. Most pups are born between June and July.
Migratory movements are not known, and genetic studies suggest that movements between islands are restricted.
Habitat and diet
This species prefers natural areas for hunting and shelter, although urban expansion has made it common to observe it hunting around artificial lights and taking refuge in cracks and cavities of buildings. It can be found from sea level up to 600 m in altitude.
This bat is insectivorous, although detailed information on its diet is lacking. It hunts in open spaces in practically all available habitats, often on the edges of forests, parks, agricultural areas, and urban areas. It usually hunts at around 25 meters in height, although sometimes lower. It is common to observe this species hunting in broad daylight, especially in the afternoon. This behavior is believed to be due to the absence of predatory birds on the islands. During the day, it tends to hunt more in inland areas than near the coast.
Echolocation
Echolocation calls are typical of the Nyctalus genus, although they tend to be at a higher frequency than those of the Leisler's bat, at around 27-33 kHz. The calls are of a quasi-constant frequency (QCF), with a duration of up to 17 ms. The pulses are usually more modulated than in other noctules. Since it does not share sympatry with any species with similar echolocation, it is easily identifiable through acoustic analysis.
Status
According to the IUCN Red List, the species is considered Vulnerable, with a negative population trend. The species is protected in various countries by national legislation under the Eurobats Agreement, Bern Convention, and the European Habitats and Species Directive. The population of this species has been estimated at 2,000-5,000 individuals, although some subpopulations have fewer than 1,000 individuals. Although not certain, it is believed that the population of Azores noctules is declining due to colony destruction, loss of hunting habitats, and the introduction of exotic plant and animal species.