17.

Azores Noctule

Nyctalus azoreum

French: Noctule des Acores / German: Azoren-Abendsegler / Spanish: Noctulo de las Azores

Other common names: Azorean Bat

Taxonomy. Pterygistes azoreum Thomas, 1901,

“St. Michael’s, Azores,” Portugal.

Nyctalus azoreum is morphologically and ecologically distinct from N. leisleri but is genetically not particularly divergent. However, there is considerable genetic divergence between different island populations of N. azoreum, indicating that the species has been present on the islands for a long time, and that there is limited breeding between islands. Monotypic.

Distribution. The Azores Archipelago on Faial, Pico, Sao Jorge, Graciosa, Terceira, Sao Miguel, and Santa Maria Is.

Descriptive notes. Head-body 51-57 mm, tail 42-43 mm, ear 12 mm, forearm 35-42 mm; weight 6-15 g. The Azores Noctule is externally very similar to Leisler’s Noctule ( Nyctalus leisleri) but smaller and darker. Dorsal pelage is dark brown with a yellowish hue, while ventral pelage is yellowish. Face, ears, and membranes are darkly pigmented;tail extends a few millimeters past uropatagium. Muzzle is short, with large glands between nostrils and eyes; ears are short and triangular, with 4-5 folds on outer edge. Tragus is very short and rounded, mushroom-shaped, as is characteristic of the genus. Skull is robust and lacks a defined forehead; skull and dentition are similar to Leisler’s Noctule overall; lower molars are nyctalodont.

Habitat. Forages in a variety of habitats across the islands. The Azores Noctule favors natural and semi-natural dry forest and heathland, although it is frequently found feeding around agricultural fields and villages. Elevation range is 0-600 m.

Food and Feeding. Insectivorous. Azores Noctules feed largely during the day, and stay high in the canopy and over the vegetation in open areas when foraging. Some individuals have been observed foraging around streetlights at night.

Breeding. Most births occur in mid-June to July; litter size is 1-2 young. Young begin to fly in about mid-July. Like many temperate bats, Azores Noctules probably exhibit delayed fertilization and mate earlier in the year.

Activity patterns. Roosts are most often found in buildings, rock crevices in cliffs, and holes in trees. Unlike most noctules and bats in general, the Azores Noctule often forages diurnally, leaving its roosts before sunset. This may be because of the lack of predation or competition with birds on the islands. Calls are similar to those of Leisler’s Noctule but at a higher maximum energy frequency (32-1 kHz).

Movements, Home range and Social organization. The Azores Noctule lives in colonies of individuals that roost together; when leaving the roost, they cluster in small groups, as do continental bats. Females create maternity colonies with only females and young from April until September or October, while males are solitary or in small groups during breeding season, although outside this period both males and females live solitarily or in small groups. Mean number of individuals in a roost, as indicated by M. Leonardo and F. M. Medeiros in 2011, was five, with a range of 1-684 individuals. Maternal roosts were up to 684 individuals in buildings, while in trees cavities they were generally 20-50 individuals, depending on the size of the cavity.

Status and Conservation. Classified as Vulnerable on The IUCN Red List. The Azores Noctule is restricted to the Azores, where it is relatively common on Sao Miguel, Faial, Terceira, and Sao Jorge. However,it is rare on Graciosa and extremely rare on Santa Maria, and it may be declining throughout its entire range due to habitat degradation, roost destruction, and other forms of human persecution. Total population is estimated to be 2000-5000 individuals, with less than 1000 individuals on Sao Miguel, where the species is most abundant. Because the species flies during the day, it is especially vulnerable to persecution by people, as colonies are easier to find. The Azores Noctule is the only mammal endemic to the Azores; the only other land mammal native to the islandsis the Greater Myotis ( Myotis myotis).

Bibliography. Boston et al. (2015), Irwin & Speakman (2003), Leonardo & Medeiros (2011), Moore (1975), Palmeirim (1991), Piraccini (2016a), Rainho et al. (2002), Salgueiro, Coelho et al. (2004), Salgueiro, Palmeirim & Coelho (2010), Salgueiro, Palmeirim, Ruedi & Coelho (2008), Salgueiro, Ruedi,Coelho & Palmeirim (2007), Skiba (2003), Speakman & Webb (1993).