Dobsonia moluccensis

Movements, Home range and Social organization. Moluccan Naked-backed Fruit Bats are highly gregarious, but roosting groups vary from solitary individuals to groups of tens, hundreds, or thousands of individuals. They will cohabit caves with Beaufort’s Naked-backed Fruit Bat (D. beauforti). Group size in tree hollows and tree crowns including coconut trees are limited to small numbers. In Australia, colonies are relatively small, approaching a maximum of 100 individuals and have been found in caves, dark areas under large boulders, old mines, abandoned houses, and dense vegetation. It exhibits extremely high thermal conductances that can be 180 % of that expected for a mammal of its body weight. Such exceptionally high thermal conductance is facilitated by naked-backed wing condition and likely assists in efficiently dumping heat in this largebodied species that roosts clumped together. Preference for roosting at interior limits of cool caves also facilitates heat dumping to cool air in cave interiors. Naked-backed wing morphology is related to its ability to fly with amazing maneuverability at low speeds, including its ability to hover and fly backward. As they search for a place to roost when approaching a cluster of roosting conspecifics, they are able to hover, repeatedly reverse direction, and then move forward slowly to land by swinging feet upward to grab onto rock. They also fold wings and dive up to 300 m to approach a particular cave entrance. If disturbed at the roost by a predator, they are highly vociferous; otherwise there are only occasional antagonistic with vocalizations coupled with wing boxing between individuals that attemptto displace each other from mates or favored roost positions. Potential predators include large pythons such as the amethystine python (Morelia amethistina) that will enter caves to feed on bats. Physiological responses to environmental temperature variation of Moluccan Naked-backed Fruit Bats appear adaptive to cave dwelling and avoidance of predation. These responses include maintenance of constant high body temperature (mean = 36 - 8 ° C), high minimum thermal conduction (mean = 180 % of mammalian mass-specific standard), and high basal metabolic rate (BMR, mean = 145 % of mammalian standard). Maintenance of high body temperature and high BMR might facilitate rapid growth and care of young (including milk production) and ability to fly instantaneously in response to a predator. High minimal termal conductance (largely through highly vascularized naked-backed wings) facilitates heat loss for a largebodied bat that otherwise might overheat in crowded roosting clusters. Large colony size also might raise cave air temperatures, making excess body heat more difficult to unload. Large colonies of Moluccan Naked-backed Fruit Bats often have infestations of large fur-dwelling bat flies including Megastrebla parvior and M. gigantea. Terrestrial leeches often hang from cave ceilings and drop on Moluccan Naked-backed Fruit Bats.

Sumber: Pteropodidae