Using next-generation sequencing to unravel the diet composition of Burrowing Parrots over the annual cycle

Understanding the diet of an organism is crucial for disentangling its role in ecosystem function, and to unravel foraging behavior, population dynamics, competitive interactions among species and evolutionary processes. Furthermore, diet studies can be useful to better interpret environmental change and its impact on wildlife. Nevertheless, studying the diet of organisms that forage over large areas can be challenging. In such cases, next-generation sequencing of DNA in fecal samples can be used to identify dietary items consumed. Using this methodology, we investigated the diet composition of the Burrowing Parrots Cyanoliseus patagonus from the El Cóndor colony, north-eastern Patagonia, Argentina. Over the annual cycle, we collected fecal samples at the roosting place used by these birds every night. We identified a large variety of plant molecular operational taxonomic units (MOTUs) in the diet of Burrowing Parrots throughout the year. Remarkably, we found that only 13% of plant MOTUs consumed were native plants. This was unexpected, suggesting a shift from a predominantly native plant-based diet in the past to a diet that is now primarily composed of introduced plants. This shift could demonstrate the behavioral flexibility of this species in adapting to current severe environmental degradation in north-eastern Patagonia. Alternatively, it could be a sign of a suboptimal strategy that could negatively impact on the persistence of the El Cóndor colony, the world's largest colony of Psittaciformes. Additionally, this methodology enabled the identification of parasites not previously recorded in the digestive tracts of Burrowing Parrots (Gongylonematidae, Hymenolepididae, Onchobothriidae, and Capillariidae).