Eastern Tube-nosed Bat

Queensland-Tube-nosed-Bat---Nyctimene-Robinsoni-copia

Eastern Tube-nosed Bat (Nyctimene robinsoni)

The eastern or Queensland tube-nosed bat (Nyctimene robinsoni) is a megabat in the family Pteropodidae that lives in north-eastern Australia. N. robinsoni is one of the few species in Pteropodidae that roosts solitarily. They get their common name from their raised tubular nostrils which is unlike most other species in the family. They are a deep brown with gray heads and sparse yellow spotting.

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(Hall and Pettigrew, 1995Milledge, 1987Riek, et al., 2010Schulz, 1997)

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. (Richards, 1986Schulz, 1997Spencer and Fleming, 1989)

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). (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. (Hall, 1983)

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. (Hall and Pettigrew, 1995Hall, 1983Nellett, 2007Richards, 1986)

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). (Hall and Pettigrew, 1995Heaney 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. (Hall and Pettigrew, 1995Riek, et al., 2010)

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. (Chapman, et al., 1994Hall, 1983Heaney and Peterson, 1984Riek, et al., 2010)

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. (Hall and Pettigrew, 1995)

 

More Info in WIKIPEDIA