How does Africa’s smallest pure grazing antelope survive the dry season? Keenan Stears & Adrian M Shrader Herbivores Body size Big or small Digestive physiology Ruminant Hindgut fermenter Ruminant body size 4 kg 1400 kg Browsers 14? kg 940 kg Grazers Restrictions High mass-specific requirements Slow passage rate Small absolute requirements & narrow muzzles Why use low quality food? (Shipley & Felicetti 2002,Clauss et al. 2013) Key question Do oribi need high quality food or do they just select it because they can? Chelmsford Dam KwaZulu-Natal 220 Oribi Seasons Dry Transitional Wet Scales Habitat Feeding station Scales Habitat Grassland Vlei Fire breaks Feeding station Plant species Plant part Greenness Nutritional intake Seasonal use Vlei Dry season= 40% Wet season= 12% Diet >90% grass Forbs & sedges <10% Transitional & wet seasons Seasonal diet 5 species made up >80% of diet 3 key species Hyparrhenia hirta Hemarthria altissima Themeda triandra Fed on grass leaves Grass greenness 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0.0 0.0 Proportion of grass greenness utilised greenness grass of Proportion Proportion of grass greenness available greenness grass of Proportion JuneJuly Aug Sep Oct Nov Dec Jan Feb JuneJuly Aug Sep Oct Nov Dec Jan Feb Very brown Mainly brown Mainly green Very green (0-25%) (26-50%) (51-75%) (76-100%) Crude Protein 80 Dry Transitional Wet 70 60 50 40 30 20 17 kg 10 7 kg 0 Crude protein intake rate (g CP/day) rate intake protein Crude June July Aug Sep Oct Nov Dec Jan Feb Unburnt grassland Firebreaks (Foose 1982) Metabolizable energy 6 Dry Transitional Wet 5 17 kg 4 3 7 kg 2 Metabolizable energy (MJ/day) energy Metabolizable 1 June July Aug Sep Oct Nov Dec Jan Feb Unburnt grasslands Firebreaks (Nagy et al. 1999) Conclusion Feed selectively Plant part Plant species Greenness Habitats Because they have to, not because they can Acknowledgements Gay Langmuir Bursary .