Nyctiellus lepidus

1.

Gervais’s Funnel-eared Bat

Nyctiellus lepidus

French: Natalide de Gervais / German: Gervais-Trichterohr / Spanish: Natalido de Gervais

Other common names: Moth Funnel-eared Bat

Taxonomy. Vespertilio lepidus P. Gervais, 1837,

Cuba.

This species is monotypic.

Distribution. Cuba (including Isla de la Juventud) and Bahamas (Eleuthera, Cat, Great Exuma,Little Exuma, and Long Is).

Descriptive notes. Ear 10-13-6 mm, forearm 26-6-31 mm (males) and 28-1-31 mm (females); weight 1.9-2.7 g (males) and 2:3-2.7 g (females). Gervais’s Funnel-eared Bat is the smallest species of funnel-eared bat, and one of the smallest bats in the world. Pelage is dense, long, grayish brown to reddish or orange-brown, lighter ventrally, and bicolored with tips darker than bases. It has relatively broad rostrum, low braincase, narrow distal one-third of ears, narrow wings, and short legs. Face lacks dermal outgrowths but has conspicuous mustache. Natalid organ of males is small, square-shaped, and located on dorsum of rostrum. Wing is attached to tibia at its distal three-quarters; free margin of uropatagium lacks fringe of hairs. First upper incisors nearly touch along skull midline, and first upper and lower premolars are markedly reduced in size.

Habitat. Mostly xeric and costal habitats but also mesic semideciduous forest at elevations of 0-422 m. Gervais’s Funnel-eared Bat roosts almost exclusively in small and large, warm and humid caves, usually in areas with low ceilings and near water bodies. It has been found once in a human structure, an abandoned hotel cistern in the Bahamas that functioned much like an inundated, low ceiling cave.

Food and Feeding. Gervais’s Funnel-eared Bat is exclusively insectivorous and eats leathoppers (Cicadellidae), planthoppers (Fulgoridae), flies (Muscidae), termites (Nasutitermes sp.), moths (Lepidoptera), and ants (Hymenoptera). Females are able to carry more weight (30% of body weight) in their stomachs than males (22% of body weight) and increase their food consumption by 34% from winter to summer; males only increase their food consumption by 8:9% from winter to summer. On average, older adults consume more food relative to body weight (21%) than younger adults (15%).

Breeding. Gervais’s Funnel-eared Bat has a single annual estrus and one young per litter. Copulation appears to take place in winter (December-February), pregnant females are found in March—July, and lactation occurs in July-September, peaking in September. Non-reproducing adult females are found throughout the year, and subadults of both sexes are found in July-September. Lactating females carry their young in flight when they average more than 35% of their mothers’ weights.

Activity patterns. Gervais’s Funnel-eared Bat is nocturnal, with two nightforaging periods. The first begins ¢.10 minutes around sunset and lasts up to 45 minutes, and the second is shorter and ends c.5 minutes around sunset. During both foraging bouts, individuals can be easily seen with unaided vision flying erratically and low within vegetation or over open pastures. Males begin and end foraging periods before females, especially those that are lactating and carrying their young in flight. Such short foraging bouts are associated with a massive exodus from their roosting caves. While roosting, individuals hang widely spaced and are generally quiet, allowing human observers to approach closely.

Movements, Home range and Social organization. Gervais’s Funnel-eared Bat has high fidelity to roost sites, and their short foraging times are associated with very small home ranges. Mark-recapture studies have shown that individuals are unable to return to their caves if released at distances greater than 2 km from their roosts. Both sexes roost separately in July-September: females gather in large maternity colonies in the deepest parts of caves, and male-only groups occupy more external areas of caves or neighboring caves where there are no maternity colonies. Non-reproductive females are occasionally found in such groups of males. Fluctuations in size of cave colonies can be associated with sexual segregation during the reproductive season. Although Gervais’s Funnel-eared Bat can coexist in the same cave with up to 15 other species of bats, it seems to prefer caves and cave areas not occupied by other species, with the exception of the Cuban Lesser Funnel-eared Bat (Chilonatalus macer), with which it will roost in closer association.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Gervais’s Funnel-eared Bat is abundant and known from 63 localities, 36 of which are day roosts. Cave colonies contain a few dozen up to a few thousand individuals. Given its ability to form large colonies in small caves or cave-like habitats and to forage over pastures and secondary vegetation, Gervais’s Funnel-eared Bat seems to be resilient and unlikely to be threatened as long asits roosts are undisturbed.

Bibliography. Allen & Sanborn (1937), Garcia & Mancina (2011), Gervais (1837), Silva-Taboada (1979), Tejedor (2011), Tejedor, Tavares & Rodriguez-Hernandez (2005).