There is little available information on the way lesser dawn fruit bats communicate and perceive their environment. The presence of long scent-dispersing "osmetrichia" hairs on males indicates the use of olfaction and is probably used in reproductive state determination and mating. In many species of bats males have a much stronger odor than females. Pteropodidae species have large, well-developed eyes, and conspicious simple ears. The perception of their environment is mostly visual. However, E. spelaea is unique in the production of wing-clapping sounds during movement in dark situations, which may be a primitive form of echolocation that aids orientation. Most Pteropodidae species locate food by smell.
Communication Channels: chemical
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Lesser dawn fruit bats are considered lower risk/least concern by the IUCN. The major threat to E. spelaea is loss and degradation of forest habitat through ongoing wood extraction and limestone quarrying. Conservation actions that are needed include monitoring and research of population numbers, range and trends. The subspecies E. spelaea glandifera of Indonesia and the Philippines and Sulawesi was reported as vulnerable 1992. Populations in Java and the Lesser Sundas Islands are considered endangered because of cave disturbance, hunting, and habitat destruction. Populations of E. spelaea glandifera in the Philippines seem more adaptable to habitat alterations but are at risk due to hunting and human disturbance.
US Federal List: no special status
CITES: appendix i
IUCN Red List of Threatened Species: least concern
There are no known adverse effects of E. spelaea on humans.
The primary significance of E. spelaea to humans is the pollination of commercially important plant species, especially durian fruits (Durio spp.), which can add up to $120 million (U.S. dollars) to the Southeast Asian economy annually. Lesser dawn bats are also hunted for use as food. Bat guano from the Philippines is harvested for use as fertilizer.
Positive Impacts: food ; produces fertilizer; pollinates crops
The primary ecological function of E. spelaea is pollination. A possible secondary role is seed dispersal, however, the use of fruit as a wild food item is not confirmed.
Ecosystem Impact: pollinates
Diet consists primarily of the nectar and pollen of night flowering plant species. Two studies state that stomach and tongue contents contained pollen exclusively. Lesser dawn fruit bats are nectarivorous generalists that have been documented feeding on over 31 plant species. The nectar and pollen of Oroxylum indicum is described as their preferred and principle food source. Eonycteris spelaea and O. indicum are referred to as an example of coevolution because the flowers are adapted to the head morphology and feeding behavior of the this bat species. Durio zibethinus, Parkia speciosa, Musa acuminata, and Ficus species are also used. Lesser dawn fruit bats have shown a particular affinity for a specific species of Agave. They use durian fruit nectar and pollen, and it is suggested that they are the among the most important pollinators of this economically important fruit. It is also reported that Eonycteris are occasional flower eaters. In captivity, individuals have been fed coconut (Cocos) pulp and guava (Psidium).
Plant Foods: fruit; nectar; pollen; flowers
Primary Diet: herbivore (Nectarivore )
Long-tongued dawn fruit bats or lesser dawn fruit bats, Eonycteris spelaea, are found throughout much of south Asia, from southern China to the islands of Indonesia, and from southwestern India to throughout the Philippines.
Biogeographic Regions: oriental (Native )
Eonycteris spelaea is almost exclusively a cave roosting species. Eonycteris major, their closest relative, has also been known to use hollow tree cavities. Eonycteris spelaea is found in various habitats ranging from forested to mixed agricultural types. They are common in cultivated areas away from forests, within forests they mostly occur in openings. Secondary lowland, primary lowland, and transitional montane-mossy forests are most often used by these bats.
Range elevation: 50 to 1,250 m.
Average elevation: 500 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest
Other Habitat Features: agricultural ; caves
There is little information available on the longevity of this species in the wild or in captivity. The highest lifespans in captivity of other Pteropodidae species include: straw-colored fruit bats (Eidolon helvum), 21.8 years; flying foxes (Pteropus), 31.4 years; and rousette fruit bats (Rousettus), 22.9 years.
Lesser dawn bats have large eyes, small, simple ears, and lack a tragus. The muzzle is narrow and the tongue long and extendable, with rasp-like papillae. Dorsal pelage is dark brown and the belly is paler. The necks of males are covered with long scent-dispersing "osmetrichia" hairs that are darker than the pelage of the head and body. The second finger is independent and lacks a claw. Molariform teeth are considerably reduced and barely extend past the gums. The dental formula in Eonycteris is i 2/2, c 1/1, pm 3/3, m 2/3 x 2 = 34. The type of tongue, a tail length between 12 and 33 mm, and absence of an index finger claw distiguishes Eonycteris.
Range mass: 35 to 82 g.
Average mass: 60 g.
Range length: 85 to 125 mm.
Range wingspan: 60 to 85 (forearm length) mm.
Average wingspan: 72.5 (forearm length) mm.
Range basal metabolic rate: 0.881 to 0.979 cm3.O2/g/hr.
Average basal metabolic rate: 0.93 cm3.O2/g/hr.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
There is very little information available on the predators of this species, nor the adaptations it uses to evade predation. Like most bats, their nocturnality, flight, and habit of roosting in inaccessible places protects them from most predation. They are likely to be vulnerable to predation by climbing snakes and nocturnal birds of prey, such as owls.
Lesser dawn fruit bats are thought to be polygynous with single males mating with multiple females. Penis, baculum, and testes size are not a factor in male reproductive success, as sperm competition does not occur as in multi-male polyandrous and polygynandrous mating systems. However, residual baculum lengths are greater than in monogamous systems. It is reasonable that body size is a factor in mate selection in both sexes as it is generally an indicator of superior genes and fitness.
Mating System: polygynous
There is conflicting information on the cycle/pattern of estrus as well as birth in E. spelaea females. One study finds females exhibiting a pattern characterized by synchronous births and seasonal, bimodal polyestry, while other sources find no synchronicity between females and no seasonal synchronicity. Lesser dawn fruit bats are polyestrus and births occur in two seasonal peaks, which is consistent with females coming into estrus twice a year. The usual number of offspring per year is two. Gestation is reported to be 3 to 4 months; however, other reports suggest gestation periods possibly as long as 200 days (between 6 and 7 months). Weaning occurs at 3 months. Females mature between 6 months and 1 year. Males mature between 1 and 2 years.
Breeding interval: Breeding intervals are unknown, but females may breed up to twice each year.
Breeding season: Breeding is not synchronized with a particular season, but tends to be bimodal.
Range number of offspring: 1 to 2.
Average number of offspring: 1.
Range gestation period: 3 to 6 months.
Average weaning age: 3 months.
Range age at sexual or reproductive maturity (female): 6 to 12 months.
Range age at sexual or reproductive maturity (male): 1 to 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Reports suggest that females are the sole providers of pre-independence parental care. After birth, altricial young take hold of a nipple and stay attached for 4 to 6 weeks as the female flies around. After this time, young can make flights independently for short distances. Complete weaning occurs at 3 months.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
