Grazing patterns of sambar deer (Cervus unicolor) and red deer (Cervus elaphus) in captivity

Abstract

Grazing behaviour was recorded in sambar deer and red deer for 24-h continuous periods, at 2-monthly intervals, over 12 months from March 1990 to March 1991. Scan-sampling was used, with observations made every 12 min. Both groups of deer grazed separate but adjoining areas of the same pasture for the duration of the study. Sambar deer grazed most actively during the night (0100-0500 h), late afternoon, and evening (1700-2100 h), whereas red deer grazed most intensely during early morning (0500-0700 h), afternoon, and early evening (1500-2000 h). This species difference in grazing pattern was not altered by season or month. Total grazing time was similar for sambar and red deer (9.1 versus 9.4 h/24 h), but sambar deer spent more time grazing during the night (6.2 versus 4.9 h/24 h; P < 0.01) and less time grazing during the day (2.9 versus 4.5 h/24 h; P < 0.01) than red deer. The ratio night grazing:daytime grazing was much greater for sambar deer (2.3:1.0) than for red deer (1.1:1.0; P < 0.001). During the day, sambar deer spent more time resting than red deer (6.4 versus 5.1 h P < 0.001), but time spent ruminating was similar (2.1 versus 1.9 h) for the two species. Rate of prehending biting was greater for sambar deer than for red deer (65 versus 48 bites/min; P < 0.001). It is suggested that longer night grazing by sambar deer may have evolved to reduce thermoregulatory stress in tropical environments and as a defensive strategy against attack by predators. Pasture mass/ha and surface height changed with season of the year, but areas grazed by both species of deer were always of similar height and mass, indicating that grazing pressures were similar. However, herbage in areas grazed by sambar deer had higher total N content and organic matter digestibility during winter, the period of lowest pasture mass/height, indicating that relative to areas grazed by red deer, grazing by sambar deer had modified forage nutritive value at this time. © 1993 Taylor & Francis Group, LLC.