Roosting Behaviour of Fruit Bats, Pteropus giganteus (Briinnich,1782) of Kyauktaga Environs

Transcription

1 Universities Research Journal 2011, Vol. 4, No. 2 Roosting Behaviour of Fruit Bats, Pteropus giganteus (Briinnich,1782) of Kyauktaga Environs Aye Aye Kyu 1, Tin Tin Moe 2 and Thet Thet Myint 3 Abstract The roosting of fruit bats species, Pteropus giganteus (Briinnich, 1782) was studied in Kyauktaga Township, Bago Region from January 2007 to November Roosting pattern and behaviour changed in association with their reproductive status and season. Altogether six roosts sites in Kyauktaga were recorded in different kokko trees, growing near and around the market. The population size of Pteropus was observed to be moderate (about 700 to 1000 bats) in all studied sites. Emergence behavior was observed to be individual pattern as neither in group nor cluster type. Emergence time seemed to be mostly related to the season rather than sunset time. Return time was early in the hot and wet season. The findings are comparatively discussed. The scaled photographs of the bats and roost sites are also given. Key word: Fruit bats Introduction Pteropus, have the dog-like facial appearance and are very large. They are also known as the flying foxes. Pteropus is further divided into 17 species groups and about 60 total species, depending on authority. Fossil records of this and other chiropteran groups are scarce due to the delicate nature of the skeletal structure of bats, but pteropid fossils have been found in Europe from the middle Oligocene and Miocene periods, in Africa from the Miocence period, and in Madagascar and the East Indies from the Pleistocene period. Pteropus is assumed to have arisen in the Australo- Pacific during the early Miocene. Their closest relatives are those of the genus Acerodon, a similar group in both size and morphology. Pteropus species are the largest of all bats, weighing up to 3.5 lb (1.6 kg) with a wingspan of up to 6 ft (1.8 m) Fur is dense and coloration is grayish brown or black. These mammals are characterized by a yellow or grayish yellow contrasting mantle (covering portions of the head, neck, and upper shoulders). Variations among species do occur, such as in the spectacled flying fox (P.conspicillatus), which has a light ring around its eyes. The external ears are small and do not have a tragus, and the tail is absent. The 1. Lecturer, Department of Zoology, Bago University 2. Lecturer, Department of Zoology, Bago University 3. Professor & Head of Department of Zoology, Bago University

2 194 Universities Research Journal 2011, Vol. 4, No. 2 second finger is independent of the third and a claw is present on the thumb. Eyes are very large, forward-facing, and highly adapted to both nocturnal and day vision this allows flying foxes to easily recognize light colors, which assists in locating food sources (Bates, 1997). During the summer, when fruit and blossoms are mature and in good supply, flying foxes organize camps. Mating takes place at this time and small groups, or harems, form. Females are seasonal breeders and usually produce one young per year; they begin to breed at two years. During mating season, flying foxes will mate more than once per day and over the course of several days. Ovulation takes place from February to April, and births occur from September to November. Lactating lasts about six weeks, and most of the female s time during the remainder of the year is spent caring for the young. The gestation period of the flying fox is six months. During that time, the sexes begin to segregate and pregnant females form a colony; each female then helps to care for the others by mutual grooming. Birth occurs during the day- when it is imminent, the female hangs by her thumbs and feet and licks her genital area until the pup s head begins to emerge-this can last up to several hours. After birth, the pup moves itself into a sucking position and attaches itself to a nipple. The mother will fly with her young for about two to three weeks. The pup has light fur, the eyes are closed, and the ear flaps are down. The mother keeps her wings wrapped around the pup for warmth. After approximately three weeks, it becomes too heavy to carry with her and is left with the other young. Upon the mother s return, she is able to recognize her offspring by its unique vocalizations. In about a month, the young become better coordinated and begin to explore, and by January and February, they begin to form small groups near their mothers. Once they become able to care for themselves, the mother will again begin to accept the advances of a male (Kung, 1982). The present finding will then provide knowledge of the ecology, habitat requirements and protective strategies for the roosting sites of Pteropus towards biodiversity conservation.

3 Universities Research Journal 2011, Vol. 4, No Materials and Methods Study Area Kyauktaga Township of Bago Region was chosen as the study area. It is located at latitude N and longitude E. It is situated feet above sea level. The study area covers an area of approximately 1093 square miles. Its northern boundary is the Phyu Township, to the east is Sittaung river, Kyaukgyi Township and Shwe Kyin Township, to the south is the Nyaunglebin Township and Daik-U Township and the western boundary is Bago Yoma. Study site Collection of bat specimen was undertaken in six study sites. Two study sites of Kokko trees are located in the Kyauktaga market and four study sites are located near the kyauktaga market and they are also Kakko trees. Two sites in the market were chosen as main sites (Plate I, II, III, IV, V). Study period The study of conducted during a period from January 2007 to November Estimation of population Population size of the bats colony was estimated by direct roost count using binocular. Collection of specimens Bats were captured by hand net while bats were in the roost during day. The specimen were collected seasonally, they were sexed adult and juvenile condition also described.

4 196 Universities Research Journal 2011, Vol. 4, No. 2 (a) Middle tree in Kyauktaga market (b) East south tree in Kyauktaga market Plate I The study sites of Kokko trees (a) South west tree in Kyauktaga market (b) Western tree in Kyauktaga market Plate II The study sites of Kokko trees Plate III Free hanging of Pteropus Plate IV Roosting behavior

5 Universities Research Journal 2011, Vol. 4, No Plate V Cluster group in Kokko trees of Pteropus Results Systematic position Systematic position of studied bat species was based on the key of Bates and Harrison (1997). Phylum Chordata Subphylum Vertebrata Class Mammalia Order Chiroptera Suborder Megachiroptera Family Pteropodidae Genus Pteropus Brisson, 1762 Species Pteropus giganteus Briinnich, 1782 Common name Fruit Bat Local name Lin-swai (Plate VI a, b)

6 198 Universities Research Journal 2011, Vol. 4, No. 2 Roosting behaviour of studied species The studied species roosted free hanging on the branch of the tree, about 150 feet ground level. Most bats were observed in cluster closely packed together in the branches of the tree. Roosting pattern changed in rainy season and also observed to cluster in the roost. In hot season, they were observed to be spacious, individually hung on the tree. In cool season they remained clustered and touched with one another throughout the day. Emergence and return time Emergence appears to vary in association with the season. Early emergence was observed during hot season and wet season whereas late emergence was in the cool season. During the cool season emergence was observed at 4:30 to 5:30 pm and the hot season and set season emergence was late with ranging from 6:00 to 7:00 pm. Emergence time concerning the relation of seasonal sunset time. They fly out individually during emergence without cluster pattern. However, initial emergence was undertaken by one or a few individuals. The return time of studied species was found to be earlier in the hot season and wet season. It was observed at 3:00 to 3:30 am and 5:00 to 5:30 am. at cool season. After the return time they are all sleep at 8:00 am., when they come back more vocalization than at other times. Faeces of studied species Waste matter egested from the studied species have no smell. The colouration of faeces is variety in colour. The faeces depend on the feeding of the species Pteropus feeds fruits and flowers. If they feed on ripe mango their faeces are yellow. Non-reproductive pattern of Pteropus Non-reproductive condition of male Pteropus could be generally classified as abdominal testes. In females, non-reproductive could be determined by absence of visual nipples or nipples with hair grown over them known to be as nulliparous. Because nipples remained conspicuous soon after female once gave birth.

7 Universities Research Journal 2011, Vol. 4, No (a) Pteropus giganteus (fruit bat) (b) Pteropus giganteus (Lateral view) Plate VI Pteropus giganteus (a) Showing two nostrils (b) Showing two pointed ears Plate VII The head of Pteropus giganteus Table (1) Roosting data of Pteropus giganteus in Kyauktaga Township Season Hours observed Roost type Hot Wet cool 8:00 am, 1:00 pm, 4:00 pm 8:00 am, 1:00 pm, 4:00 pm 8:00 am, 1:00 pm, 4:00 pm Solitary Solitary cluster

8 200 Universities Research Journal 2011, Vol. 4, No :30 4:32: :35 4:37:30 4:40 4:42:30 4:45 4:47:30 Number of bats 4:50 4:52:30 4:55 4:57:30 5:00 5:02:30 5:05 5:07:30 5:10 5:12:30 5:15 5:17:30 5:20 5:22:30 5:25 5:27:30 5:30 Time (pm) Fig. 1 Emergence pattern of Pteropus in cool season 4:35 5:10 Fig. 2 Emergence time and number of Pteropus in cool season

9 Universities Research Journal 2011, Vol. 4, No Number of bats :00 6:02:30 6:05 6:07:30 6:10 6:12:30 6:15 6:17:30 6:20 6:22:30 6:25 6:27:30 6:30 6:32:30 6:35 6:37:30 6:40 6:42:30 6:45 6:47:30 6:50 6:52:30 6:55 6;57:30 7:00 Time (pm) Fig. 3 Emergence pattern of Pteropus in hot and wet season 7:00 6:30 Fig. 4 Emergence time and number of Pteropus in hot and wet season

10 202 Universities Research Journal 2011, Vol. 4, No. 2 Discussion The studied bats are a colonial species that lives in large diurnal roost habit and are usually located in well established Kokko trees. A colony of some 700 to 1000 species is situated in trees of Kyauktaga market and its environs. Bates and Harrison (1997) reported that colonies are usually located in close association with man and tend to be found in cities and villages. This species also appears to roost in higher branch of tree in all studied sites. Most of the Kokko trees are 150 feet tall. In the market, the girth of tree is 23 feet. Kyauktaga township is located near Bago Yoma. The feeding area is very large for bats colonies. Fruits and flowers abundance in Bago Yoma. Emergence patterns of bats are of two patterns seems through out the year. Emergence patterns of Pteropus is more or less related to the number. The first emergence in small number and gradually larger till peak emergence is reached after haft of total emergence time. Emergence time is most likely to be either associated with the light. Emergence time and returns time seems to be related to the season rather than sunset time. In the present work, locating females occurred in May and juvenile s practice flight is July. Pteropus are direct economic value, either by human use for food or by the sale of the animal. Fruit bats have occasionally been considered beneficial for medical use, especially to cure asthma disease. In Kyauktaga were harvested for their meat which was thought to be a cure for women disease. Still, by far the most notable contribution is that of pollination and seed dispersal. Concerning bat population that decline in bat abundance and diversity could have serious consequence for ecosystem function. The promoted conservation also concerned with public an awareness in the study areas. It could be considered as fewer disturbances by human. Pteropus can be considered as low risk for extinction. However, their conservation status should not be negligible. Moreover bat conservation for long term viability of bat population is providing local organizations with sufficient information that the diverse ecological importance and also protective strategies of roosting sites of Pteropus towards the biodiversity conservation.

11 Universities Research Journal 2011, Vol. 4, No Acknowledgements We would like to express our gratitude to Dr. Kyi Soe, Rector, Bago University for his encouragement, valuable suggestions and permission to conduct this work. We wish to mention our deepest thanks to the staff of, Kyauktaga Township, Development Affairs for giving us help whenever and wherever needed. References Altringham, John D. (1996) Bats, Biology, and Behavior. New York: Oxford University Press. Banack, Sandra Anne. (1998) Diet Selection and Resource Use by Flying Foxes (Genus Pteropus). Ecology 79: Bates, P. J. J., and D. L. Harrison. (1997) Bats of the Indian Subcontinent, Sevenoaks, England: Harrison Zoological Museum. Bonaccorso, F. J. (1998) Bats of Papua New Guinea. Washington: Conservation International,. Fenton, M. B. (1985) Communication in the Chiroptera. Bloomington: Indiana University Press. Fujita, Marty. (1998) Flying Foxes and Economics. Bats 6, no. 1: 49. Hall, Leslie, and Greg Richards. Flying Foxes, Fruit and BlossomBats of Australia. Malabar, FL: Krieger Publishing Company, Hill, J. E., and J. D. Smith. (1984) Bats: A Natural History. London: British Museum of Natural History. Kunz, T. H., and M. B. Fenton. (2003) Bat Ecology. Chicago: University of Chicago Press,. Kunz, T. H. (1982) Ecology of Bats. New York: Plenum Press. Kunz, Thomas, and Paul Racey. (1998) Bat Biology and Conservation. Washington, DC: Smithsonian Institution Press. Mickleburgh, Simon, Anthony M. Hutson, and Paul Racey (1992). Old World Fruit Bats: An Action Plan for Their Conservation. Gland, Switzerland: IUCN. Neuweiler, Gerhard. (2000) The Biology of Bats. New York: Oxford University Press. Nowak, Ronald. (1999) Walker s Mammals of the World, 6th ed. Baltimore and London: The John Hopkins University Press. Rainey, William E. (1990) The Flying Foxes: Becoming a Rare Commodity. Bats 8, no. 1: 69.