Chaerephon nigeriae Thomas 1913

66.

Nigerian Free-tailed Bat

Chaerephon nigeriae

French: Tadaride du Nigeria / German: Nigeria-Bulldogfledermaus / Spanish: Caerepon de Nigeria

Other common names: Nigerian Wrinkle-lipped Bat

Taxonomy. Chaerephon mnigeriae Thomas, 1913,

“Zaria Province, Northern Nigeria.”

Subspecific ranges are disjunct. Two subspecies are recognized.

Subspecies and Distribution.

C.n.nigeriaeThomas,1913—SierraLeonetoEthiopiaandSWArabia.

C. n. spillmanni Monard, 1933 — Angola to Tanzania and S to N Namibia and N Botswana.

Descriptive notes. Head-body c.68-78 mm, tail 31-52 mm, ear 15-23 mm, hindfoot 9-13 mm, forearm 41-51 mm; weight 10-26 g. Pelage of the Nigerian Free-tailed Bat is short and blackish brown above and below, with bare patch between shoulders, and no mid-ventral markings, but a conspicuous flank-stripe of long white hairs. Upperlip has 5-7 (spillmanni) or 7-8 (nigeriae) well-defined wrinkles on each side and many spoon-hairs. Ears are blackish and medium-sized, just reaching snout when laid forward, and joined by interaural band of skin that covers interaural pocket which contains erectile hairs (c. 6 mm) giving rise to a crest in males; in females, hairs are replaced by a naked pocket. Tragus is small and rectangular, with top side straight or markedly concave, almost fully concealed by antitragus. Antitragus is much larger than tragus, roughly trapezoid but top corners are sometimes rounded. In race nigeriae, wing membranes are blackish brown dorsally, whitish ventrally, especially close to body, and tail membrane is blackish brown; in spillmanni, wings are whitish and semi-translucent dorsally and ventrally, or blackish, and tail membrane is dark brown dorsally and paler ventrally. Skin on forearm is dark brown dorsally extending narrowly onto wing membrane as a faint dark stripe. There are no gular or tail glands. Anterior palate is not emarginated and basisphenoid pits are shallow to moderately deep. M® has third ridge more than one-half the length of second ridge. Chromosomal complement has 2n = 48 and FNa = 62.

Habitat. Race nigeriae has been recorded in degraded forest and Guinea savanna. Race spillmanni has been recorded from mopane, miombo, and Acacia (Fabaceae) woodlands, often associated with water. The species has been found at elevations of up to 1400 m at the Cuanavale River source lake in central Angola.

Food and Feeding. In Zimbabwe, diet comprised mostly Coleoptera, with a much lower occurrence of Lepidoptera.

Breeding. Female Nigerian Free-tailed Bats give birth to a single young. Pregnantfemales have been recorded in late October (Zimbabwe) and late January (Namibia), while lactating females have been recorded in mid-November (Zambia) and mid-December (Botswana). Juveniles have been recorded in December (Botswana) and January (Zambia).

Activity patterns. Nigerian Free-tailed Bats are nocturnal. In one colony in a roof, squeaking was heard 30 minutes before dusk and individuals emerged ten minutes later; they returned later, and some hunted in the vicinity of the roost. They roost under the bark of dead trees, in small caves, and in the roofs of houses. Echolocation call is shallow FM with low frequency (peak frequency 17 kHz on average), with long duration (10 milliseconds on average) and narrow bandwidth (10 kHz on average). Predators include bat hawks (Macheiramphus alcinus).

Movements, Home range and Social organization. Nigerian Free-tailed Bats roost communally in groups of up to 100 individuals. A maternity roost discovered in December in the Okavango Delta, Botswana, comprised over 25 adults, including at least 13 lactating females, with two naked young and three furred young. A colony roosting under bark was observed sharing this roost with Pipistrelluslike bats.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. ACR (2017), Cotterill & Happold (2013f), Monadjem, Bergmans, Hutson et al. (2017), Monadjem, Taylor et al. (2010), Rosevear (1965).