Thursday, July 3, 2008

Vanishing Species - The Gaur (Indian Bison)

An Article by Mohan Pai

Gaur (Indian Bison)
(Bos gaurus)
The Largest Bovine in the world is also an endangered animal.
Gaur (Bos gaurus) commonly referred as the Indian bison, is the largest living bovine, confined to the Asiatic region. The gaur, belongs to the group of wild oxen which include the Asiatic buffalo, African buffalo, true cattle and bison. The ancestors of the gaur are known to have evolved in Asia some 20 million years ago. Gaur bulls are larger in stature as compared to the cows. Bulls weigh 600 -1000 kg and stand 1.6 - 1.9 m at shoulder whereas cows are shorter and weigh about one fourth the males. These animals are known to have acute sense of smell and good hearing but the visual senses are relatively less developed. One of the most striking features of gaur is the muscular ridge on its shoulders, which slopes down to the middle of the back where it ends in an abrupt dip. This is often referred to as the dorsal ridge and is the result of the extension of the dorsal vertebrae. Both sexes have horns and in the males especially larger at the base with more outward swath and lesser incurving at the tips. There is a high bulging forehead ridge between the horns referred to as bos. The average spread / length of one horn is 80-100 cm. The distance between tips of horns may be up to 120 cm. The colour of the eyes are brown.The old males have two prominent skin folds (dewlap), one small at the chin and a long one hanging below throat. At the time of birth newly born calves are light golden yellow in colour. The younger bulls and females have brown pelage but the older males are almost jet black. The forehead is ashy and both hind and fore legs are white or slightly yellowish colour up to the knees, forming stockings. In Satpura there are four totally white Gaurs, presumably albinos, who, amid their black companions, appear like ghosts!
The present and the past distribution of gaur suggests that B. gaurus is an animal of the Indo-Malayan realm, and would have traversed into the Indian sub-continent through the North-eastern region downwards to the eastern peninsula and then west to the Central Indian highlands and to the Ghats southwards. The gaur population in India occurs in more or less isolated pockets largely corresponding to the major mountain systems of the Western Ghats, the Central Indian highlands and the north-eastern Himalayas. Apart from this gaur are also found in forests of South Bihar, West Bengal and South-eastern peninsula. Their habitats range from Tropical Wet, Semi-Wet Evergreen and bamboo forests in the North-east to Tropical Moist Deciduous in the Western Ghats to Tropical Dry Deciduous forests in Central India to Shola forests and Tropical Thorn forests on the eastern slopes in the Western Ghats. In these areas gaur are known to occur, in relatively undisturbed habitats, up to elevations of 2500 m. Gaur occurs in Nepal, Bhutan, Bangladesh, Myanmar (Burma), Thailand, Laos, Cambodia, Vietnam and West Malaysia.
Estimated population of gaur in India is approximately 23,500.
Gaur is a gregarious and sociable animal. The group size may range from 2 to 16 animals or, sometimes more than 20 animals. A typical group consists of cows and few calves, one to two adult bulls and sub adults. Old males are generally solitary in nature and join the group, more frequently, during the rut. Younger and old solitary bulls at times associate with other males to form bachelor groups. Adult cows generally lead the group. Cows and young usually stay in a group. The strongest bond is of mother and the calf.
Cows give birth to a singe calf after a gestation period of eight to nine months. Twins are unknown. The bulls exhibit flehmen, an up curled lip movement, when approaching a cow in heat. The cow moves away from the herd before giving birth and remains with the calf for few days before rejoining the herd. The newly born calf becomes active after few minutes of birth and stays with the cow. For almost 5 to 8 months the young suckles milk and then switches over to green feed.
Disease is the primary cause of natural mortality in free ranging gaur. Gaur have succumbed to epidemics of foot and mouth disease, rinderpest and anthrax in many areas. Riderpest took a heavy toll in Bandipur and Mudumalai Sanctuaries in 1968 and Peryiar in 1974-75. Predation by tiger (Panthera tigris) is another cause of mortality in gaur, and tiger is the major predator. Leopard is also known to predate on calves and yearlings. Wild dogs have also been reported to attack gaur. Poaching of gaur has been reported from the borders of Kerala-Karnataka, Kerala-Tamil Nadu and in the North East
The early morning and evening hours are predominant feeding periods. During the hot hours of the day gaur retire to the shade of thick trees or tall bushes. On an average they feed for 15 to 18 hours a day. Their diet chiefly includes young and mature leaves of trees, shrubs, herbs, bamboo shoots and buds and some fruits. Like other herbivores gaur also visit salt licks periodically for minerals. Gaur needs water every day and may visit water bodies twice a day during the hottest periods. While feeding they move to water holes and then resume feeding.
The mating season of gaur varies through the entire distribution range. December-January is the peak mating season for gaur in central India. In south India, this may range from November to March.
Leadership among gaur is only apparent during travels of a group from one place to another in a single file when an animal takes a leading position in initiating or directing the movement prior to their shift from a forest patch. Leadership is not readily detectable particularly during foraging. Females generally lead a group. In case of all male groups, the older and larger male leads the herd, i.e. age and size being the criterion for determining of the leadership of the group.
Licking in gaur is a social gesture, which probably facilitates to minimize aggression (tension), strengthen the social bond, assertion of the hierarchy, cleaning, and during courtship. During the rest hours such an activity is conspicuous. Members of all age and sex class participate in such an activity. The bulls lick the cows more during courtship. Adult females take part in grooming more compared to other age –sex classes. The mother constantly licks the newly born calves. Licking is mostly oriented to the head and the neck regions that are inaccessible to self-licking.
Gaur exhibit different vocalizations advertising their mood and temperament. They snort and give phoo / pffhong calls when alarmed or surprised, the moo call is given when they come out to feed in the open, the bulls during rut give out a high pitched and far carrying whistle-like call. The cow – calf bond is perhaps the strongest association in gaur. The cows about to give birth get separated from the group and become solitary. The cows with the newly born calf remain away from the group for some days and then rejoin the group. The newly born calf becomes active after a few hours from birth. It stays with the mother for almost 5 to 8 months.
Having an acute sense of smell gaur can detect danger very well and are extremely alert as they sense it. When startled or threatened due to the presence of predators they assume an ‘alert’ posture – the head is held up to the level of dorsal ridge and facing the source of threat. When alarmed, gaur at times thump their forelegs onto the ground in unison and communicate to the other members of the group with a series of sounds and gestures. Gaur seldom attacks people. When harassed by predators like tiger, gaur is known to attack humans without any provocation.
Gaur is an Endangered animal listed in Schedule – I of the Indian Wildlife Protection Act of 1972 and is included in the Appendix I of the Conservation on International trade in Endangered Species of Wild Fauna and Flora (CITES). IUCN has classified gaur as ‘Vulnerable’.
Past records indicate that populations of gaur have succumbed to epidemics of foot and mouth disease (FMD), rinderpest and anthrax in many areas of distribution. This is largely due to the fact that gaur has little immunity to some cattle diseases. In fact no wild animals in India so profoundly influenced by transmitted infections from domestic livestock as gaur. Further, poaching of animals and sport hunting in the past, and habitat degradation are mainly responsible for the decline or extinction of small local populations.
The overall trend in gaur population reported from the 52 PA’s, showed that, much of the population is stable with exception to some PA’s of Peninsula India and North-East where population has declined.The Western Ghats and their outflanking hills in the south India constitute one of the most extensive extant strongholds of gaur, with good numbers in Wynaad – Nagarhole – Mudumalai – Bandipur complex. The other areas with sizeable population of gaur in Peninsular India are Billiranganswamy Temple Wildlife Sanctuary (Karnataka), Tadoba – Andhari Tiger Reserve and Melghat Tiger Reserve in Maharashtra. Rapid loss and fragmentation of forests, disease and illegal hunting seem to be the primary cause of decline of the gaur population in India. This has been a result of the mounting anthropogenic pressures. If not kept under check, this may result in the slow retreat of the gaur from other habitats too. There is a need to implement a wide vaccination programme for the domestic livestock in and around protected areas to prevent these livestock transmitting diseases to the gaur.

Gaur habitats in India

Acknowledgements:M.K.S. Pasha, K. Sankar, Q. Qureshi and G. Areendran

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