A recipe for recovery: Diet as a decisive tool in species conservation

Abstract

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 preferred browsing on specific trees based on their nutritional and defensive traits. Gazelles maintained a narrow nutritional target, tightly regulated their protein intake, and aimed to increase consumption of non-structural carbohydrates. Dorcas gazelles consumed a very different diet from the Acacia gazelle, but converged to a similar intake target. By considering both dietary and nutritional data, 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 results link species-specific dietary strategies with resource selection and resulting interspecific interactions, demonstrating the importance of nutritional ecology as a major conservation tool.