Nilgiritragus hylocrius (Ogilby, 1838)

Don E. Wilson & Russell A. Mittermeier, 2011, Bovidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 444-779 : 683

187.

Nilgiri Tahr

Nilgiritragus hylocrius

French: Mouflon des Nilgiri / German: Nilgiri-Tahr / Spanish: Tahr del Nilgiri

Other common names: Nilgiri Ibex

Taxonomy. Kemas hylocrius Ogilby, 1838 ,

Nilgiri Hills, S India.

Formerly classified in the genus Hemutragus . Nilgiritragus is a sister-group of Quis. Monotypic.

Distribution. SW India in the Western Ghats range along the border of Kerala and Tamil Nadu.

Descriptive notes. Few measurements available. Shoulder height 80-100 cm; weight 50-100 kg. Horn length 28-44. 5 cm (males), horn basal girth 12:7-25 cm (males). The keel of the horn is confined to the inner edge. The pelage of females is dusky-brown to gray-brown, with a whitish abdomen. Males are dark brown to blue-black. In some, the sides of the neck are gray, and in older males, the lower back,sides, and occasionally the rump are pale in color. The throat, abdomen, and carpal joints are white. Both sexes have a dark, mid-dorsal band extending the length of the back. In adult males, the dark muzzle is separated from the dark cheek by a pale stripe from the ear down the side of the muzzle. Diploid chromosome number is 58.

Habitat. The Nilgiri Thar is the only member of the tribe Caprini that lives in the tropics. Annual temperature fluctuations are not pronounced at elevations of 1200-2600 m in the Western Ghats, where they occur. They live near cliffs and steep slopes; rolling grasslands provide their preferred forage. Some areas receive an average annual rainfall of 4000 mm, mostly from June to August, during the monsoon. The grasslands are on steep slopes below cliffs and among rock slabs, interspersed with shrubs and forested deep valleys; the trees rarely exceed ten meters in height. Cliffs, which provide security, are a limiting factor because of their limited availability. Nilgiri Tahrs are distributed in subpopulations, some with limited exchange of individuals. They are the prey of Leopards (Panthera pardus) and Dholes (Cuon alpinus ), but predation is not a significant mortality factor.

Food and Feeding. Primarily grazers, with grasses comprising a much greater volume than forbs, shrubs, and trees. During the dry season, browse consumption increases. In drier, lowland habitats, they are probably primarily browsers. They occasionally feed at the edges of forest patches.

Breeding. Mating season is in July-August, during the monsoon season, and most births occur in January-February, during the period of least thermal stress. Gestation period is 175-185 days. Females give birth to one offspring. Twinning is extremely rare. Unlike temperate caprins, whose mating season occurs during the end of the period of decreasing daylength, Nilgiri Tahrs mate during the period of increasing daylength. Some females whose offspring die at an early age conceive twice in one year and hence can have two young per year. Second births occur during the monsoon, during which period newborns are subject to thermal stress. Young born during the monsoon are exposed to wet, cold, windy weather and have a higher mortality than those born during January and February.

Activity patterns. Most tahrs feed in early morning until about 08:00 h. From 10:30 h to 14:30 h about half are active. A second feeding peak occurs after 16:00 h.

Movements, Home range and Social organization. Basic social units consist of mixed groups and male groups. Mixed groups (females, offspring, subadults, and during the rut, adult males) average 42 (2-150) animals. Male groups form during the non-mating season and have an average of three (2-20) animals, but solitary males are common. Populations in two areas were 13:4% and 15-2% adult males, 7-9% and 4-2% subadult males, 34-2% and 33-6% females, 18:9% and 17-3% yearlings, and 25-6% and 29-6% young. Density increases with the increase in cliff area. The population in the Eravikulam National Park had a mean density of 6-27 ind/km? (5:68-8:16 ind/km?) in April, the highest tahr density recorded throughout their range. Females comprised about 40-45% of the combined subpopulations. The ratio of young-of-the-year to adult female was 30-90:100 and the yearling ratio was 20-55:100 females. The sex ratio varied from 53-7 to 66-7 males:100 females, with a mean of 59-7 males:100 females. Annual mortality within the park was 44-52% for young, 31-37% for yearlings and 17-24% for adults. At birth,life expectancy was 3-3-5 years. Herds continually change members between groups. Older males are rarely permanent members of mixed herds, but rather continually enter and leave mixed herds. Social behaviors include butting horns, but most encounters involve body contact and displays.

Status and Conservation. Classified as Endangered on The IUCN Red List and in Schedule I of the Wildlife Protection Act of India. Total population is probably less than 2000 animals, in scattered populations, of which ¢.800 tahrs inhabit the Eravikulam National Park. Most populations are fragmented, unmonitored, their status is unknown, and many consist of less than 50 animals occurring in 50-60 localities. Also, many populations occur outside protected areas and are highly vulnerable to extirpation. Nilgiri Tahrs are subjected to poaching, human intrusions, and disturbance, exotic tree monocultures, and competition with livestock. Community-based conservation programs are lacking. Ecological studies to determine habitat requirements and status of tahr habitats are a high priority as are annual monitoring of populations with a reliable monitoring protocol. A landscape management approach should be used to develop a metapopulation network to ensure the genetic viability of isolated populations. Enlargement of present protected areas and reestablishment of tahrs in areas where they have been extirpated are also essential, as is the enforcement of game laws.

Bibliography. Abraham, Easa & Sivaram (2006), Alempath & Rice (2008), Daniels, Easa & Alembath (2008), Fox & Johnsingh (1997), Groves & Grubb (2011), Grubb (2005), Menon (2009), Rice (1981, 1988a, 1988b, 1988c, 1988d, 1989), Ropiquet & Hassanin (2005), Schaller (1967a, 1977).

Figures

On following pages: 189. Isfahan Sheep (Ovis isphahanica); 190. Laristan Sheep (Ovis laristanica); 191. Ladakh Urial (Ovis vignei); 192. Punjab Urial (Ovis punjabiensis); 193. Bukhara Urial (Ovis bochariensis); 194. Arabian Wild Sheep (Ovis arabica); 195. Afghan Urial (Ovis cycloceros).

Distribution. SW India in the Western Ghats range along the border of Kerala and Tamil Nadu.