Old World Fruit Bat

The Old World fruit bats belong to the family  Pteropodidae. This family contains more than 180 species of large-eyed fruit-eating or flower-feeding bats. They are widely spread over from Africa to Southeast Asia and Australia.  Most of the old world fruit bats are open in trees and some are inhabited rocks, caves and buildings. A few of the representatives for the family Pteropodidae are listed here. Asian species Cynopterus, a short-nosed fruit bat. The Epomophorus, epauletted fruit bats are a well known African species. Males of these species have tufts of pale hair on the shoulders. The Hypsignathus monstrosus is a hammer-headed fruit bat, that has a large, blunt muzzle and pendulous lips.

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Characteristics of Old World Fruit Bats 

Among the species in the Pteropodids family, the most well-known species are flying foxes. They are widely found in tropical islands of Madagascar, Australia and Indonesia. This is one of the largest bats. The food for some other smallest bats of the family is the pollen and nectar-eating long-tongued fruit bats. The Macroglossus is one of the well-known pollen and nectar-eating long-tongued fruit bats. The smallest bats are the length of head and body together is about  6 to 7 cm. Their wingspan is about 25 cm. The species of the Pteropodids are in various colours, some are red or yellow and some are striped or spotted. All the bats do not have a clear vision, they use sonar for finding the echolocation and avoid their obstacles.

Physical Appearance 

The head and body length of species of Pteropodidae ranges from 50mm to 406 mm. Many genres have more similar characteristics. The nectar-eating bats have relatively long rostrum,  large eyes, and simple external ears as like the members of the family a dog or fox. The genera Paranyctimene and Nyctimene are containing tubular nostrils that project from the upper surface of the snout. On the skull of old world fruit bats follows postorbital processes are present over the orbital region.  Each adult fruit bats have not more than two upper and two lower incisors teeth. But the cheek and canine dentition may vary depends on the species. The tongue of old world fruit bats and nectar-feeding bats is highly protrusible and they are often complex with terminal papillae.

The chest of bats are robust and they are comprised of the down-thrusting pectoralis and serratus muscles.  The fruit bat wingspan articulating regions of the humerus never are connected with the scapula, So, the locking mechanism in fruit-eating bats are different from other bats that occur in the shoulder joint. The fruit bat wingspan’s second digit is relatively independent of the third digit and contains a vestigial claw that adorns the wing’s leading edge. 

The old world fruit bats have handing modifications and relocation of the hip socket. The acetabulum, a socket of the hip bone is shifted upward and dorsally and articulates with a large-headed femur for a wider range of motion. The legs of bats cannot be positioned in a straight line under the body like other mammals. The bat mammals have large claws on their feet. Further, the pteropodids use a tendon-ratchet system, which allows them to hang without prolonged muscular contraction. While the bats are flying, the legs will manipulate a  primitive uropatagium. Other than Notopteris, most of the bat species are tailless or with just a spicule of a tail.

Many species in the Pteropodidae family shows sexual dimorphism. The males of Hypsignathus monstrosus which are widely found in Africa have outlandish facial features, while female bats have the conservative fox-like look. The male bats of the genus Epomops contain distinctive white patches in association with a glandular membrane on their shoulders, whereas those white patches are absent in female bats. All males of Old World fruit bats are larger than the females. The penis of all the bats in this family remains a pendant and freely movable organ, resembling that of primates. But the young bats are pendant and freely movable organs, resembling that of Primates. 

Habitats

Pteropodids can usually encounter in primary or mature secondary forests.  Few species of Old World fruit bats are inhabiting near the savannahs, here the bats are roost in bushes and low trees.  More than half of the 41 genera are roost in trees. Some of the gregarious species roost on the canopy-emergent trees, open branches of large. The species of the Pteropodidae family roost singly or make a small group. They can widely found in the dead aerial roots, palm leaves, and even arboreal termite nests. All bats have special characteristics called cryptic colouration so that they can wrap themselves with their wings to project themselves as dead leaves.  Cynopterus sphinx is one of the fruit-eating bats that can construct tents by chewing folds in palm leaves.  Caves, mines, cliff walls, and the eaves of buildings are serving the roosting locations for about 17 species of fruit-eating bats. Most cave-dwelling fruit bats are decreased and they are limited towards the lit areas near the opening. 

Usually, the members of the Pteropodidae family include flowering plants in their diets. In such cases, the flying foxes prefer woodlands or orchards for food. The canopy emergent fruiting trees,  like baobab and fig trees are the frequently used food source for the bats. The flowers of baobab trees have a strong fragrance and they are usually found on top of the trees, so the bats are easily accessing these fruits and flowers. The flower syndrome of baobab trees is also known as chiropterophily. Some fruit-eating bats can be found in the coastal areas and they can intake saltwater to compensate for the nutrients that are lacking in their fruit diets. 

Few fruit-eating bats are migratory, the Eidolon helvum is one of the largest fruit-eating bats that gather in large numbers and they migrate for hundreds of kilometres northward according to the seasonal rains, only to return to southern Africa at the end of the rainy season. Pteropus scapulatus is a Little red flying fox, their populations are large and they have erratic movements within Australia according to the flowering periods of Eucalyptus trees. Many species in the Pteropodidae family roost in islands and make daily migrations to the mainland for foraging. Varies species of bats are range from sea level to 2500 m.

Behaviour

The behaviour of Pteropodids is different from all other Chiropterans. The Rousettus species do not echolocate. The species in the Pteropodidae family shows vision and olfaction to perceive their world. Based on the characteristics of species in the Pteropodidae family can divide into two groups based on size.  Smaller pteropodids species such as Epomops buttikorteri, Micropteropus pusilla, and Epomophorus wahlbergi have shorter, deeper wings that allow for more manoeuvrable flight under the canopy. Larger pteropodid species such as Acerodon species and Eidolon, Pteropus have longer, narrower wings which help them for efficient long distant flight. 

Usually, the Pteropodid species shows various degrees of coloniality. Some species are solitary and the roost of some species may also contain up to 200,000 individuals. The roost size of bats may vary depending on the seasons, this is probably due to a depletion of local food sources. Some roosts may also contain other species of bats. So, the roost selection in pteropodids remains poorly understood. The roost of  Pteropodids bats is in a wide range of habitats, from cultivated kapok plantations to rainforests and mangroves. Some bat species prefer a particular type of plant for their diet. The fruit-eating bats show long term fidelity to the roost sites, where they remain undisturbed. Some species of bats in Australia have made a record by having the same roost site for more than  80 years. 

Reproduction 

The mating behaviour of old world fruit bats are highly variable and much information about it remains unknown. The male bats of Hypsignathus set up lekking territories twice a year and their female bats have some unique vocalizations and wing-flapping displays to attract male bats. The males of epauletted fruit bats often show their concealed epaulettes, which means the hair tufts near their shoulders and produce courting calls to attract their female bats. Many species form harems, which consist of one dominant male and many females. Here, the bachelor male bats roost separately. 

Most of the bats have only one reproduction per year but some Pteropodidae species are polyestrous, which have two seasons of reproductive cycles that correspond to the annual wet and dry seasons. Usually, one young one can be born at the end of a single gestation period but can expect twins in some cases. During fertilization, the ova implantation in the uteri can be immediate or delayed, probably in response to the environment. Once implanted, the embryo may develop and they also get delayed. Generally, the fruit-eating bats give birth to young one while the fruits are available in large quantities. Macroglossus minimus, a Long-tongued nectar bat can exhibit asynchronous breeding and sperm storage further, they can suggest birth during a rainy season.

Usually, the Pregnant female bats leave their social roosts to form nursery groups with other pregnant females. The female bats in the nursery roosts will form their own social network and take care of each other throughout the gestation period. Generally, the gestation period will last for about 4 to 6 months in bats. This can be delayed if there is a delay in implantation. After the long study about the gestation period, the Pteropodidae usually occurs in the wet periods both in the northern latitudes and the southern latitudes. Some bats show polyestrous, which can give birth during both of these rainy seasons. As the survival rates for the young bats are high when their breeding season falls on rainy season. Further, lactation in bat mammals can occur when fruit availability is at a maximum. The birth of a young one, the adult bats follows postpartum estrous and subsequent mating. After weaning, the young bats may stay with their mothers for up to 4 months. Young bats require 2 years to attain sexual maturity.  Female bats can attain sexual maturity much earlier than male bats. 

The female fruit bat wingspans are primarily responsible for rearing the young one. Further, the lactation period can last for seven weeks to 4 months after giving birth to a young one. So, the mother bats can care for their young ones for the long term. The male bats from Dyacopterus genus have functional mammary glands which can lactate their juvenile and both parents can feed their baby. 

The Old world fruit bats belong to the family Pteropodidae. Around 180 species of large-eyed fruit-eating or flower-feeding bats are kept under this family and they are widely spread over from Africa to Southeast Asia and Australia. Some fruit bat eating mammals are solitary and some are gregarious. Most fruit bat wingspan roost in the open areas like trees, but some species prefer caves, rocks, or buildings.