Hygroscopic Food: a Source of Water for Desert Antelopes?

Abstract

ORYX (Oryx beisa) and Grant's gazelle (Gazella granti) survive droughts in hot semi-deserts, apparently without drinking. Zebu cattle (Bos indicus), however, must drink frequently to survive. The actual water requirements of the three species are 2–4 per cent of their body weight per day¹. All eat dry food, which at mid-day contains only 1 per cent free water. Where do the antelopes get the water they require ? Schmidt-Nielsen² suggested that hygroscopic plants might be an important source of water for nocturnal animals. I collected plants which were eaten by antelopes during a drought, determined the rate at which the dry leaves gain water at temperatures and humidities measured during the drought, and calculated the amount of water available to the antelopes if they feed at night.