Feeding Ecology of the Four-Horned Antelope (Tetracerus quadricornis, de Blainville 1816) in Bardia National Park, Nepal

Abstract

Feeding ecology of Four-horned antelope Tetracerus quadricornis was assessed in Bardia National Park, Nepal during summer, monsoon and winter seasons to determine the diet composition, seasonal variation in diets and to assess niche breadth of food plants. Systematic belt transects were used in the field to collect reference plants’ parts and FHA fecal samples while microhistologcal technique was used to determine diet. Microphotographs of different parts of 104 plants were prepared and 3000 fragments of 100 faecal samples (summer=60, monsoon=20, winter=20) were analyzed. Diet composition was expressed in terms of percent occurrence while Chi-square test was used to assess seasonal variation in diet and Levin’s niche breadth to evaluate degree of selectivity of food plants. The FHA was found to be a mixed feeder feeding on 15 tree species, 15 shrubs, 8 forbs, 5 grasses and 2 climbers belonging to 20 different families. It fed on 10 species of monocots and 35 species of dicots. Trees were the major food plants (25.87%), followed by shrubs (21.3 %), forbs (18.2 %), grasses (10.5 %) and climbers (4.36%). Plants of Gramineae family were consumed in highest proportion (17.64 %), followed by Acanthaceae (9.13 %) Rubiaceae (7.8 %), Asteraceae (6.56 %), Euphorbiaceae (6.4 %) and others. Metragyna parviflora, Bridelia retusa, Bambusa vulgare, Hymenodictyon arixenese and Zizyphus mauritiana were major tree species while Berlaria cristata, Pogostemon benghalensis Achyranthus sps, Clerodendrum viscosum were among shrubs. Ageratum cristata and Blumea virens were the main forbs. Eulaliopsis binata and Imperata cylindrica were the principal grass species. Climber Trachetospermum lucidum was consumed in small proportion. There was significant difference in consumption of functional plants (χ 2 = 112.20, d.f. = 10, p= < 2.2e-16) as well as species (χ = 969.31, d.f. = 90, p= < 2.2e-16) in three seasons. Trees contributed the major percentage of diet in all three seasons. Shrubs were consumed relatively in higher proportion in winter (29.00 %), than in summer (19.89 %) and monsoon (17.83 %). The preference order of forbs followed from summer (20.56 %) to monsoon (17.83 %) and winter (11.50 %). Grasses in monsoon were consumed distinctly in higher percentage (16.83 %) than in summer (10.22 %) and winter (5.00 %). Climbers contributed in small proportion in all three seasons. Browse to grass ratio was maximum in winter (6.08) while it declined to 3.82 in summer and to 1.97 in monsoon. The niche breadth (B ) of the food plants was 0.050 showing that the FHAs are highly selective of specific forage plants. Niche breadth was broader in summer season (0.045) but narrowed to 0.039 in monsoon and to 0.028 in winter. FHAs in BNP are concentrate feeders and browsers with a high degree of food plant selectivity. Similar studies are to be conducted in other landscapes also and with sympatric and potential competitor species to understand its niche overlaps and degree of competition