Ecology of the Hog Deer in Royal Chitwan National Park, Nepal

The hog deer (Axis porcinus) is listed as endangered throughout much of its range in southern Asia. In Royal Chitwan National Park, Nepal, it is one of the principal prey species of the end Bengal tiger (Panthera tigris). We studied bog deer in Royal Chitwan National Park during 1981-83 to obtain information on the morphological features, sex and age ratios, group size and composition, reproduction, mortality, movement, activity patterns, home ranges, habitat use, food habits, food availability, and behavior of hog deer in Chitwan Park. Ninety-five hog deer were captured and measured; 21 were radio collared and monitored for 6,250 hours. Maximum weights (mean for males = 42.7 kg; mean for females = 32.2 kg) and lengths (mean for males = 1,278 mm; mean for females = 1,206 mm) were attained at 2-3 years of age. Sex ratio of captured and observed (n = 570) deer combined was 56 males: 100 females. Groups of up to 20 deer were observed during February through April, after the first fires in the grasslands, but the basic social group consisted of an adult female and her juvenile offspring. The peak fawning season was March through April, but females gave birth from the end of january through April. One female had a documented 213-day gestation period. Both males and females attained sexual maturity at about 15 months. Litter size was normally 1, and 13 fawns/100 adults were captured or observed in the field. During all seasons, the deer fed in the mornings and evenings and bedded and ruminated during the hot part of the day. They were active during 41% of the day and 26-29% of the night. Home ranges overlapped extensively, and mean home ranges were estimated at 60 ha for females and 80 ha for males. Home range shape was dictated by food and water. Small home ranges indicated that hog deer were sedentary, preferring grasslands where food, cover, and water were available. Habitat use, based on transmitter locations and direct observations, showed that hog deer used grasslands almost exclusively and preferred grasslands to sal (Shorea robusta) and riverine forests. Foraging and feeding behavior, recorded inside a 4-ha enclosure, indicated that grasses, ferns, semal (Bombax ceiba) flowers, and vellor (Trewia nudiflora) fruits were important food items. Saccharum spp., Imperata cylindrica, and Cynodon dactylon composed 70% of the grass species available as food and cover. Tall grasses seem to be invading short grasslands, reducing available food for hog deer. Experiments should be conducted on increasing interspersion of short grasses for food and tall grass for cover. Research on succession also would facilitate development of future management strategies.