Conservation implications of dietary strategies in the critically endangered Acacia gazelle (Gazella arabica acacia)

Animals consume foods in specific quantities and ratios to meet a multi-dimensional nutrient target that maximizes their fitness. Attempts to reach this target in an ever-changing nutritional landscape often influence animal foraging behavior, habitat choice, and food-web interactions. Consequently, understanding the nutritional ecology of a species is instrumental in developing efficient management plans for its conservation. We quantified the dietary considerations of a critically endangered population of Acacia gazelles (Gazella arabica acacia), and compared their diet and nutrition to that of the sympatric Gazella dorcas, using behavioral observations coupled with nutritional and secondary metabolite quantification, and morphological measurements of trees. Acacia gazelles mainly consumed resources from two subspecies of the umbrella-thorn acacia (Vachellia tortilis) that differ in morphology, nutritional composition, and phenology, and prioritized consumption of specific trees based on their nutritional and defensive traits. Gazelles maintained a narrow nutritional target, tightly regulated their protein intake, and prioritized consumption of non-structural carbohydrates. Dorcas gazelles consumed a very different diet from the Acacia gazelle, but converged to a similar intake target. We conclude that suitable habitats for Acacia gazelle reintroduction must include sympatric populations of the two V. tortilis subspecies, that nutritional deficiency is unlikely to play a major role in explaining the slow rate of population recovery, and that the seemingly low competition between the two gazelle species does not necessitate controlling the Dorcas gazelle population. Our work demonstrates the importance of nutritional ecology as a major conservation tool.