Macroglossus sobrinus
greater long-tongued fruit bat

Macroglossus sobrinus is found in the southerneastern Palearctic and throughout the Oriental region along with its sister taxon Macroglossus minimus. Populations can be found in India, Myanmar, Thailand, Sumatra and Java, as well as the islands of Sipora, Sibnerut, Mentawei, Nias, and Krakatoa. (Bates and Harrison, 1997; Wilson and Reeder, 1993)

In Malaysia, greater long-tongued fruit bats occupy a variety of habitats, including mangrove swamps, montane forests, and lowland forests. When range overlaps occur between Macroglossus sobrinus and Macroglossus minimus, it appears that M. minimus is restricted to coastal mangrove swamps while M. sobrinus is found in montane and lowland forests. A separate study in Thailand found the species in evergreen forests below 1918 m, where pollen is available year round. (Bates and Harrison, 1997; Lekagul and McNeely, 1988)

Greater long-tongued fruit bats have slender, delicate skulls with long rostra. Length of skull is at least 30 mm. The skull has a low occipital crest, a palate ending beyond the last molar, and weakly developed postorbital processes. The braincase is deflected downward. Males have larger skulls than females. The mandible has low processes and is long and slender with a groove for the tongue at the front. The highly protrusible tongue has a feathery tip made of filiform papillae and is used in feeding on pollen. (Bates and Harrison, 1997; Lekagul and McNeely, 1988)

Greater long-tongued fruit bats have reduced dentition: cheek teeth are narrow and low-crowned. All teeth are well spaced linearly along the jaw. The incisor tooth row is elliptical with a large gap between both the upper and lower incisors through which the tongue protrudes. The gap between the lower incisors is larger relative to the upper gap. The incisors are forward-sloping and small, and the canines are short and sharp. (Bates and Harrison, 1997; Lekagul and McNeely, 1988)

The long pelage of Macroglossus sobrinus lacks markings. It is soft, fine, and light reddish-brown, with the chest colored lighter than the head. On the dorsal surface, the pelage is uniformly clay-brown. Hairs are present the inner wing membranes, forearms, and upper surface of the tibiae. Members of this species exhibit no sexual dimorphism in fur color. The ears are medium-sized with small antitragal lobes. Both ear and wing skin is dark brown. Short hairs thickly cover the upper and lower surfaces of the interfemoral membrane. These bats lack an external tail and have reduced calcars. (Bates and Harrison, 1997; Lekagul and McNeely, 1988)

Basal metabolic rate has not been documented, but in their close relative Macroglossus minimus, it falls around 0.88 and 1.48 cm^3 of oxygen/g/hr for lower range bats and highland bats, respectively. Macroglossus sobrinus closely resemble Macroglossus minimus, but the paler under parts and longer muzzle are distinguishing characteristics of the former species. (Bates and Harrison, 1997; Bonaccorso and McNab, 1997; Lekagul and McNeely, 1988)

The estimated lifespan for Macroglossus sobrinus is 4 to 6 years. The species has not been bred in captivity. (Zoo Outreach Organisation, 2002)

Greater long-tongued fruit bats typically forage alone, with pairs found rarely. Individuals tend to roost alone, although small groups are also found. In Malaysia, these groups ranged from 5 to 10 individuals, most commonly found in palm trees, roofs, and banana plants. Macroglossus sobrinus, along with Macroglossus minimus, are responsible for the first peak feeding activity by Chiroptera each night. (Bates and Harrison, 1997; Gould, 1978)

Information on the behavior of Macroglossus sobrinus is scarce, but more research has been done on the behavior of its close relative, Macroglossus minimus. During the day, when inactive, Macroglossus minimus of Papua New Guinea roost individually. They have home ranges of around 5.8 hectare with very little overlap. This, along with prominent sternal scent glands, suggests territoriality, although this has not been definitively shown. In addition, Macroglossus minimus engages in “probing forays," potentially to scout new habitat. When temperatures reach 11-29 degrees Celsius, Macroglossus minimus enter a torpid state, maintaining a body temperature of 2-5 degrees Celsius above the ambient temperature. (Bonaccorso and McNab, 1997; Winkelmann et al., 2003)

Home Range

Home ranges are estimated to be around 1 to 2 km, although home range may be smaller in areas with higher densities of banana plants. (Bates and Harrison, 1997)

Like most members of Pteropodidae, greater long-tongued fruit bats do not use echolocation. These bats emit audible calls of less than 9 kHz with a duration of about 15 milliseconds and inter-call intervals around 128 milliseconds. Macroglossus sobrinus occasionally emits double pulses or clicks. The purpose of these double pulses is not yet known. In stressful disturbance situations, these bats emit harsh broadband signals as distress calls. The call is a large series of clicks with duration greater than 100 milliseconds. (Funakoshi, Zubaid, and Matsumura, 1995)

The diet of the greater long-tongued fruit bats varies among localities, but it appears to consist primarily of pollen and nectar, although soft fruit may be taken as well. In Malaysia, Macroglossus sobrinus was found to feed on the pollen and nectar of three species of wild banana, Dubanga grandiflora flowers, and soft fruit. Start (1974) estimated that an adult Macroglossus sobrinus could survive solely off two to three wild banana plants; due to the flowering habits of the banana, food would be available year-long. Generally, Macroglossus sobrinus is considered a banana specialist, although secondary food sources are also used. (Bates and Harrison, 1997; Lekagul and McNeely, 1988; Winkelmann et al., 2003)

Greater long-tongued fruit bats move around 1 to 2 km per night while feeding, although this range may be significantly smaller in areas with higher densities of wild banana plants. It has been hypothesized (Gould, 1978) that individuals may follow set routes as they travel from plant to plant each night. (Bates and Harrison, 1997; Gould, 1978; Lekagul and McNeely, 1988)

Predators specific to Macroglossus sobrinus are unknown, but Old World fruit bats generally have few predators. Snakes, birds of prey, and carnivorous mammals occasional prey on them. Of these, snakes are most common predators of bats in roosts. While predation influences behavior and feeding habits, it does not significantly affect population size. (Mickleburg, Hutson, and Racey, 1992)

One of the major roles that Macroglossus sobrinus fills is that of a pollinator to a variety of ecologically important plant species. A study in 2002 found that Macroglossus sobrinus serves as an effective pollinator for Musa itinerans, an important pioneer species in the rain forests of southwestern China. A separate study found that Macroglossus sobrinus serves an important role in the pollination of a wild banana, Musa acuminata. (Gould, 1978; Itino, Kato, and Hotta, 1991)

Macroglossus sobrinus populations in Cambodia serves as a potential host for a variety of viruses in the Lyssavirus family. This is evidenced by the presence of anti-lyssavirus neutralizing antibodies in serum samples. (Walston et al., 2004)

Greater long-tongued fruit bats have antigens for the Lyssavirus – a family of viruses containing rabies. It indicates that they may be carriers for the Lyssavirus, and could infect humans with rabies. Their large localized population density results in their being classified as vermin in India, although they do not harm people and are beneficial through pollination services. (Walston et al., 2004)

Greater long-tongued fruit bats are primary pollinators of wild bananas, Musa acuminata. In addition to producing a widely-consumed fruit, the wild banana tree is also known as a pioneer species. It is useful in recolonizing depleted tropical forest. (Itino, Kato, and Hotta, 1991; Liu et al., 2002)

Due to the large range of Macroglossus sobrinus, the species is considered stable. The lack of endemic subspecies coupled with the locally common nature of Macroglossus sobrinus contributes to this assessment. In addition, the species is present in multiple protected areas across South Asia, minimizing the need for conservation measures. Although the species is generally “safe," it may be locally threatened as a result of habitat loss due to bamboo extraction and the conversion of land for agricultural use. Molur et. al. (2008) recommend survey, population monitoring, and habitat management to the Indian government. (Bates and Harrison, 1997; Molur et al., 2008)

Macroglossus sobrinus was considered to be a subspecies of Macroglossus minimus, from the works of E. Geoffrey in 1810 until the more recent research done by Hill in 1983. Currently, a variety of different authors consider M. sobrinus to be a distinct species, including Corbet and Hill (1992), Koopman (1993), Bates and Harrison (1997) and Simmons (2005). All Indian specimens are referred to by the subspecies name of Macroglossus sobrinus sobrinus. The species name Macroglossus sobrinus is also synonymous with Macroglossus fraternus. The common name is variable, although most sources use either “hill long-tongued fruit bats” or “greater long-tongued fruit bats”. (Bates and Harrison, 1997; Lekagul and McNeely, 1988; Molur et al., 2008; Wilson and Reeder, 1993)