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Grouping characteristics and population structure of chital (Axis axis Erxleben), sambar (Cervus unicolor Kerr), nilgai (Boselaphus tragocamelus Pallas) and chinkara. (Gazella bennetti Sykes) were studied in dry tropical forests of Ranthambhore Tiger Reserve in semi-arid western India during November 2000 to April 2001. Mean and typical group sizes were highest for chital (winter: 4.7 and 9.2, respectively; summer: 4.5, 7.9), followed by sambar (winter: 3.4, 4.2; summer: 4.2, 6.8), nilgai (winter: 2.9, 4.5; summer: 2.5, 4.9) and chinkara (winter: 2.6, 3.3; summer: 2.5, 3.2). Population structure was biased towards females in chital (86.4 males: 100 females) and sambar (83.2:100), while it was biased towards males in nilgaii (116.8:100) and chinkara (119.8:100). Ratio of young to adult females was highest for sambar (38.2 young: 100 females), followed by chinkara (35.2:100), chital (28.0:100) and nilgai (23.9:100). Variations in grouping patterns according to habitat and season have been investigated. The importance of constant monitoring of ungulate population structure is emphasised for this drought prone region.