Nyctimene robinsoni

Geographic Range

Queensland tube-nosed fruit bats ( Nyctimene robinsoni ) are found along the east coast of Queensland, Australia ranging from northern New South Wales to the Cape York Peninsula. Few observations have been made on the occurrence of Queensland tube-nosed fruit bats south of the Queensland border but they are believed to have a more scattered distribution at the southern end of their range. Recordings of the southern range of Queensland tube-nosed fruit bats were taken south of Nightcap National Park at Snows Creek (a tributary of Coopers Creek found 26 km north north east of Lismore, New South Wales) and around the forest canopy at Boomerang Falls Flora Reserve (about 5 km south south west of Snows Creek). Queensland tube-nosed fruit bats are generally dispersed along the coast throughout their range; the farthest inland recording is also the most southerly recording and comes from the Culmaran Creek valley in Richmond Range State Forest approximately 84 km east of the coast. A specimen housed by the Australian Museum is reported to come from as far south as Wee Jasper, New South Wales, however this is believed to be attributed to a labeling error and this specimen has been determined to be island tube-nosed fruit bat .

• Biogeographic Regions
• australian australian
  • native native

Habitat

Although regarded as a rainforest specialist Queensland tube-nosed fruit bats are found throughout complex notophyll vine forests, Araucarian notophyll vine forests, mixed tall open forests, sclerophyll vegetation, and in urban areas. Accounts of Queensland tube-nosed fruit bats suggest that they prefer to roost amongst foliage in the rainforest sub-canopy layer where they find effective camouflage within the dried leaves. However they have also been noted in exposed trees on forest margins. Individuals may roost alone from approximately 4 to 6 m above the ground to higher up and out of sight in the canopy. Individuals show day-roost site fidelity over short periods, mainly during ripe fruit abundances, within an area; but may change roost sites as a predator avoidance strategy. Day-roost sites chosen by Queensland tube-nosed fruit bats are variable and include: primary forest sites, isolated tropical fig trees ( Fiscus veriegata ), hind-dune mangroves, and second-growth forests near mangroves.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• rainforest rainforest

• Aquatic Biomes
• coastal coastal

• Other Habitat Features
• urban urban
• suburban suburban
• agricultural agricultural

Physical Description

The skull of the genus of tube-nosed fruit bats can be described as short and heavy with anteriorly deep rostrum. Their lacrimal widths are a greater than distance from orbit to nares. They have narrow braincase, slight basicranial flexion, and have an aveolar line which projects backwards and passes through the condyle. Tube-nosed fruit bats have a non-tubular occiput and anteriorly fused premaxillaries. They have no narrowing of the bony palate or only slight narrowing behind maxillary toothrows. Tube-nosed fruit bats have parallel upper canines and the distance between posterior molars is equal to width of interpterygoid fossa. They have angular process of mandible that is greatly reduced and long tubular nostrils. Their dental formula is incisors 1/0, canines, 1/1, premolars 3/3, and molars 1/2 equaling 24. P2/ and P/2 are well developed and equal in height to the cingulum of the canines. The rest of the cheekteeth are molariform all of which have high well-developed anterior cusps except for M/2, which is low crowned and about half the size of the other molariform teeth. Tongues of tube-nosed fruit bats have four circumvallate papillae ((Anersen, 1912; Miller 1907) in Heaney and Peterson 1984).

The dentition of the genus of tube-nosed fruit bats is unique because they lack incisors on the lower jaw; the lower canines function in place of the missing incisors. The modified lower canines nearly come into contact with each other and close against the 2 upper incisors when biting. This odd dentition is attributed to a distant ancestor with reduced biting teeth, possibly due to a liquid based diet. In returning to a diet of fruit a new biting mechanism evolved.

Queensland tube-nosed fruit bats have brown wings characteristically speckled with yellow and lime-green spots. These spots provide each individual with their own “spot code” as no two bats have the same pattern. Their fur is grey to red-brown with a dark strip of fur centered down the dorsal side of their body. One of the most characteristic features of this fruit bat is their large bulging tubular nostrils (protruding 5 to 6 mm from the face). This along with the characteristic yellow to green spots on their wings, face, and ears, as well as their bulging eyes distinguishes them from all other Australian bats.

The wings of Queensland tube-nosed fruit bats are short and broad compared to other members of the old world fruit bats family. Queensland tube-nosed fruit bats gave a well-developed tail and a claw on the index finger (Anersen, 1912; Miller 1907 as cited in Heaney and Peterson 1984).

Queensland tube-nosed fruit bats have a measured basal metabolic rate of 54.7 cubic cm oxygen per h, and daily body tempatures ranging from 35 degrees C to 37 degrees C. Heterothermy is rarely seen in the old world fruit bats family, however Queensland tube-nosed fruit bats have the ability to rapidly drop their body teperature, metobolic rate, and enter torpor during day or night. Unlike other bat species which use shivering or brown fat as their heat generating mechanisms, Queensland tube-nosed fruit bats produce heat much more rapidly via tachycardia which is under nervous and hormonal control.

Queensland tube-nosed fruit bats have an average head and body length of 100 to 110 mm as well as an average tail length of 20 to 25 mm. Commonly used as a proxy for body condition by bat researchers the average forearm length and mass are 60 to 70 mm and 30 to 50 g respectively. Although little evidence of the sexual dimorphism in Queensland tube-nosed fruit bats has been documented, sexual dimorphism of the pelvic girdle has been suggested based on palpations of adult bats. The palpations of the pelvic girdle of Queensland tube-nosed fruit bats indicate that they may exhibit similar sexual dimorphism to other species of Australian flying foxes . Females have open, V-shaped pelvic girdles and the males have closed, O-shaped pelvic girdles. Females have also been noted as having a more lightly colored pelage than males while sub-adults have a more intermediate coloration. Despite this the overall color patterns and average mass for both sexes are the same.

An analysis of the cellular DNA content of Queensland tube-nosed fruit bats has revealed that they have fewer genes than any other mammal (smallest genome size). Their total genome size is approximately half that of the human genome, which has implications about which parts of the genomes of humans, or other mammals, are redundant.

• Other Physical Features
• endothermic endothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently
• sexes shaped differently

Reproduction

Little is known about the mating systems of Queensland tube-nosed fruit bats.

Little is known about the reproductive biology of Queensland tube-nosed fruit bats; however most species belonging to the old world fruit bats family have long periods of mating, long pregnancies, and long lactation periods, with the reproductive cycle lasting around 12 months in many species. Like the majority of old world fruit bats species Queensland tube-nosed fruit bats are seasonal breeders.

Female Queensland tube-nosed fruit bats give birth to one pup between October and December. Close relatives Philippine tube-nosed fruit bats are found in primary forests near water bodies and among upper canopy foliage which is similar to the habitat requirements to Queensland tube-nosed fruit bats. The similarities between these two species make Philippine tube-nosed fruit bats a decent proxy for the reproduction of Queensland tube-nosed fruit bats. Heidmen (1987) found Philippine tube-nosed fruit bats also have a single young each year. Gestation in Philippine tube-nosed fruit bats are around three and a half months long while lactation lasts four months or longer.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Queensland tube-nosed fruit bats have long periods of lactation and the single pup is carried by the mother until it grows rather large. No information is currently available about parental care in this genus.

• Parental Investment
• altricial altricial
• female parental care female parental care

Lifespan/Longevity

Nothing is known about the longevity of Queensland tube-nosed fruit bats. However old world fruit bats live at least 30 years in wild and captive settings.

Behavior

Queensland tube-nosed fruit bats are believed to roost exclusively solitarily. One study in captivity found they used aggressive behavior, such as vocalized threats and even physical attacks, when held captive with conspecifics, regardless of sex. However a different study captured an adult female and sub-adult male in two different nets and found these two bats to be more affiliative. They were observed in close contact, even embracing. Although Queensland tube-nosed fruit bats roost exclusively in a solitary fashion, they have been found to feed in a more gregarious manner with multiple individuals feeding in a single tree. These conflicting observations on the social behavior of Queensland tube-nosed fruit bats may be due to the costs associated with cluster roosting, which would dampen the efficacy of their camouflage. Such costs would not be imposed while foraging in the dark and the ripeness of fruit on individual trees would also result in clusters of bats feeding on the same tree. Queensland tube-nosed fruit bats have also been observed feeding simultaneously with spectacled flying fox in the same tree.

The short broad wings of Queensland tube-nosed fruit bats provide them with a low aspect ratio (wing length to width) which allows for great maneuverability. This low aspect ratio allows them to hover for several seconds and change the direction they are facing while hovering. This behavior is rare for bats and is usually only seen in small light-weight gleaners.

Observations made of southern populations of Queensland tube-nosed fruit bats documented behaviors not reported in northern populations (which have been more thoroughly investigated). These behaviors include the requirement to drink after prolonged hot and dry weather, as well as a lack of activity during the cooler months of the year. Also, it includes the movement of individuals into adjacent open forests and moist tall open forests for occasional foraging and drinking.

• Key Behaviors
• arboreal arboreal
• flies
• nocturnal nocturnal
• motile motile
• daily torpor
• solitary solitary

Home Range

Queensland tube-nosed fruit bats roost solitarily in the sub-canopy of trees during the day and feed on nearby fruiting trees within 200 m of their day roost at night. Although generally found foraging within 200 m of their day roost sites they have been captured from 63 m to 1012 m from their roosting sites using mist nets. Queensland tube-nosed fruit bats have been found to change their roosting and feeding locations in an opportunistic manner as they will move into new areas when food availability changes. Although they do change their roosting or feeding sites, they will also remain within a small area for prolonged periods of time during local food abundances.

Communication and Perception

The tubular shaped nostrils were once believed to function as snorkels to aid Queensland tube-nosed fruit bats in feeding on messy fruit meals. However observations made of Queensland tube-nosed fruit bats while feeding have revealed that they are not messy eaters, indicating that the tubular nostrils must serve some other purpose. Further investigation into the tubular nostrils has revealed that the nostrils can open and close and move independently of each other. This opening and closing of the nostrils occurs in response to auditory, visual, and olfactory cues and allows Queensland tube-nosed fruit bats to scan their surrounds via olfaction. Like stereo vision from two eyes or stereo hearing from two ears the independent functioning of the two nostrils allows for stereo olfaction, providing independent measures of aroma concentrations. The use of modified stereo olfaction system allows them to locate and follow odor plumes in a three dimensional realm. This stereo olfaction system aides in finding preferred fig fruits throughout the Australian rainforests.

Queensland tube-nosed fruit bats communicate via characteristic whistling calls which also serve as a reliable indication of their presence within an area.

• Communication Channels
• visual visual
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Queensland tube-nosed fruit bats are specialist frugivores feeding mainly on 3 species of fig ( Ficus copiosa ; Ficus nodosa ; Ficus variegata ). They are also known to feed on lillypilly ( Syzigium corniflorum ), the exotics guava and soursop ( Psidium guajava ; Annona muricata ) around orchards and ona pioneer species ( Fiscus racemos ) around abandoned pastures. The majority of individuals found feeding on soursop are female which has been attributed to the different nutritional requirements of pregnant and lactating females, particularly as soursop has a much higher fat and protein content than the native figs. Foraging behavior is restricted to the understory where cauliflorous (trunk-fruiting) trees are visited. Queensland tube-nosed fruit bats generally forage on trees within close proximity to their day roosts. Fruit may be carried away to be eaten or consumed on site at the tree where the fruit was growing. Individuals can carry fruit weighing over half of their own body weight. In one instance a 54 g bat was recorded carrying a 30 g fig. Multiple individuals will feed simultaneously on the same tree and have even been noted feeding along with spectacled flying foxes .

• Primary Diet
• herbivore herbivore
  • frugivore frugivore

• Plant Foods
• fruit
• nectar
• pollen
• flowers

Predation

By wrapping their wings around their body, the colored spots of their wings, face, and ears make Queensland tube-nosed fruit bats cryptic when roosting during the day amongst dense sun-mottled foliage. The color pattern of them is well adapted for camouflage within the canopy as their dark dorsal stripe also resembles the center rib and stem of a dead leaf. Their solitary roosting behavior may allow for enhanced efficacy of their cryptic coloration, as larger groups would make this color pattern appear more conspicuous. Queensland tube-nosed fruit bats also limit their activity during full moon phases; this may be attributable to predator avoidance for visual nocturnal predators such as owls.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Queensland tube-nosed fruit bats are important seed dispersers and pollinators for the Australian ecosystem. They are the only small, understory, seed-dispersing bat in Australian tropical forests. When compared to the tropical forests of southeast Asia and central America, which have many species of small, understory, fruit-eating bats that share the task of dispersing seeds, the importance of the role played by Queensland tube-nosed fruit bats in Australian rainforests is quite apparent.

Queensland tube-nosed fruit bats have been found with parasitic mites ( Meristaspis spp. ), which are common wing mites of old World fruit bats .

• Ecosystem Impact
• disperses seeds
• pollinates

Economic Importance for Humans: Positive

Queensland tube-nosed fruit bats aid in forest succession as well as dispersal and propagation of figs, providing enhanced economic value to old world tropical forests.

• Positive Impacts
• food food
• produces fertilizer
• pollinates crops

Economic Importance for Humans: Negative

Increasing numbers of exotic fruit orchards in regions where Queensland tube-nosed fruit bats are present have resulted in an increase of reports of these bats damaging orchard fruits such as starfruit ( Averrhoa muricata ; Averrhoa carambola ).

• Negative Impacts
• crop pest

Conservation Status

Queensland tube-nosed fruit bats have been noted as being vulnerable (NSW TSC act) due to human development. Much of this concern is related to entanglement in barbed wire fences. Increases in the number of orchards in Australia has led to increased conflict with the farming community. Farmers have been known to hang nets around orchards to keep the bats away from fruit crops. Bats that become entangled in the nets are left to starve. Therefore understanding the biology of Queensland tube-nosed fruit bats is particularly important for management strategies around fruit orchards in order to minimize the damage to the fruit as well as the bats.

Additional Links

Encyclopedia of Life

Contributors

Steve Smith (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Laura Podzikowski (editor), Special Projects.

References

Booth, C. 2007. Barbed Wire Action Plan. Queensland Conservation, Brisbane , 2: 1-17.

Chapman, A., L. Hall, M. Bennett. 1994. Sexual Dimorphism in the Pelvic Girdle of Australian Flying Foxes. Australian Journal of Zoology , 42: 261-265.

Domrow, R. 1967. Mite parasites of small mammals from scrub typhus foci in Australia. Australian Journal of Zoology , 15: 759-798.

Hall, L., J. Pettigrew. 1995. The bat with the stereo nose. Australian Natural History , 24: 26-28.

Hall, L. 1983. Queensland Tube-nosed Bat Nyctimene robinsoni.. Pp. 286-287 in Complete book of Australian mammals. . North Ryde, NSW: Cornstalk Pub..

Heaney, L., R. Peterson. 1984. A new species of tube-nosed fruit bat (Nyctimene) from Negros Island, Philippines (Mammalia: Pteropodidae). Occasional papers of the Museum of Zoology, University of Michigan , 708: 1-16.

Heideman, P. 1987. The reproductive ecology of a community of Philippine fruit bats (Pteropodidae, Megachiroptera). Doctoral dissertation, University of Michigan , 1: 205.

Milledge, D. 1987. Notes on the occurrence of the Queensland Tube-nosed Bat Nyctimene robinsoni in north-eastern New South Wales.. Macroderma , 3: 28-30.

Muscarella, R., T. Fleming. 2007. The role of frugivorous bats in tropical forest succession.. Biological Reviews , 82: 573-590.

Nellett, K. 2007. Analyzing Site Loyalty in Nyctimene robinsoni at the End of the Dry Season. ISP Collection , 144: 1-31.

Nowak, R. 1994. Walker's Bats of the World . Baltimore, MD: The Johns Hopkins University Press.

O'Brien, G. 1993. Seasonal reproduction in flying foxes, reviewed in the context of other tropical mammals.. Reproduction, fertility and development , 5: 499-521.

Richards, G. 1986. Notes on the natural history of the Queensland tube-nosed bat, Nyctimene robinsoni.. Macroderma , 2: 64-67.

Riek, A., G. Kortner, F. Geiser. 2010. Thermobiology, energetics and activity patterns of the Eastern tube-nosed bat (Nyctimene robinsoni) in the Australian tropics: effect of temperature and lunar cycle.. Journal of Experimental Biology , 213: 25-57.

Schulz, M. 1997. Notes on the eastern tube-nosed bat, Nyctimene robinsoni, from the Richmond Range, northeastern New South Wales.. Australian Mammalogy , 20: 127-130.

Schwab, I., J. Pettigrew. 2005. A choroidal sleight of hand.. British Journal of Ophthalmology , 89: 1398.

Spencer, H., T. Fleming. 1989. Roosting and Foraging Behavior of the Queensland Tube-Nosed Bat, Nyctimene-Robinsoni (Pteropodidae)-Preliminary Radio-Tracking Observations.. Wildlife Research , 16: 413-420.