Why Black Goats in Hot Deserts? Effects of Coat Color on Heat Exchanges of Wild and Domestic Goats

Abstract

Black goats are the most abundant domestic animal in the Negev and Sinai deserts. These goats possess a number of complex physiological adaptations for dealing with a hot desert environment. It seemed possible that their black coat might also be an adaptation for this environment, reducing gain and the use of water for evaporative cooling. To test this possibility, we compared the rates at which black goats, white goats, and ibex (a wild goat native to the desert) gained and evaporated water in a hot desert at midday. Two methods were used simultaneously to calculate the net rate of gain by radiation and convection (Ḣgain): a heat balance and a heat flux method. The balance method involved measuring rates of production, storage, and evaporative loss. Ḣgain is the sum of rates of evaporative loss plus storage minus metabolic production. The flux method involved calculating avenues of non-evaporative exchange (radiation, conduction, and ...