Rousettus aegyptiacus (Egyptian rousette, Fruit bat, Egyptian fruit bat)

Egiptiese vrugtevlermuis, vrugtevlermuis [Afrikaans]

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Deuterostomia > Chordata > Craniata > Vertebrata (vertebrates)  > Gnathostomata (jawed vertebrates) > Teleostomi (teleost fish) > Osteichthyes (bony fish) > Class: Sarcopterygii (lobe-finned fish) > Stegocephalia (terrestrial vertebrates) > Reptiliomorpha > Amniota > Synapsida (mammal-like reptiles) > Therapsida > Theriodontia >  Cynodontia > Mammalia (mammals) > Placentalia (placental mammals) > Laurasiatheria > Chiroptera (bats) > Megachiroptera > Family: Pteropodidae (fruit bats)

Description

Size: Body length 15 cm; forearm length 9 – 10.5 cm; wingspan 60 cm; mass 130 g

Dental Formula:  ICPM = 34

Egyptian fruit bats got their name as the first specimen of this species was described from the Great Pyramid of Giza. They are large and plain coloured bats without distinctive markings. The upperparts vary from dark brown to grayish- brown and the underparts are a lighter grey. A paler yellowish collar is present on the neck and the throat may have a brownish tinge. The head is dog-like in shape with widely spaced simple ears. The eyes are large, characteristic of a nocturnal animal. The second finger is independent of the wing membrane, and like the thumb has a claw.

Distribution and habitat

Occurs widely throughout sub-Saharan Africa. In the southern African subregion it is found in the northeastern parts and along the eastern coastal band from Cape Town to Mozambique. Habitats include forest, riverine woodland and savannah, wherever there is a supply of ripe fruit. Requires caves or caverns in vicinity as roosts.

Behaviour

The Egyptian fruit bat has very good eyesight and is the only fruit bat with the ability to echolocate. The tongue emits a clicking sound (that can be heard by humans) and the echoes are picked up by the ears this allows the bat to pinpoint the position of any obstacles in the cave. This ability makes them the only fruit eating bats that can roost in caves that are completely dark. The Egyptian fruit bat can form large colonies consisting of several thousand animals that are constantly chirping and chattering. They roost in caves during the day and leave to feed at dusk or late evening, they may make round trips of 40-50 km from the roost to forage. While roosting they hang from the cave roof by one foot with the wings closely folded around the body.

Food

A wide range of soft fruit, nectar, pollen and flowers. Their preference is for ripe palatable fruit of many indigenous trees including figs, yellowwoods, and Cape Ash. They have been recorded feeding on the pollen and nectar of the baobab, the sausage tree and the cotton tree. In addition they also feed on soft-fleshed cultivated fruits such as mangos, guavas, avocados, bananas, litchi and dates. Plant-visiting bats are important for the pollination and seed dispersal of many fruit bearing trees, this includes the economically important plants too.

Breeding

After a gestation period of about 105 days, a single young is born, rarely twins, from late winter to early summer. The mother gives birth to her pup in her normal upside down hanging position and catches the baby in her wings. The pup is born with its eyes closed and ears folded back. They cling tightly to their mother’s ventral surface for the first 6 weeks, the duration of the suckling period. After this the mother then leaves her young in the cave while she forages and returns with food for it. She identifies her baby by its smell. The babies start to fly at about 9-10 weeks and then search for food with the rest of the colony. During the mating season the females and their pups form maternity colonies separate from the males.

Threats

Throughout the world many bat populations are declining, but currently the Egyptian fruit bats are classified as low risk with regard to conservation status. The fruit bats are sometimes killed in an attempt to reduce damage to fruit crops. Fruit bats should in theory pose very little if any threat to commercial fruit crops, as bats consume the fruit when it is ripe and fruit is picked for the commercial market well-before this stage. In South Africa the fruit bats are said to cause significant damage to litchi crops. In residential areas, fruit bats can be regarded as a nuisance for the mess that they make by defaecating on the walls of houses. An effective deterrent is to illuminate the walls.