Diet composition of reintroduced Red-and-Green Macaws (Ara chloropterus) reflects gradual adaption to life in the wild

Abstract

Over the last two centuries, the Red-and-green Macaw (Ara chloropterus) has become locally extinct in Argentina. In an attempt to restore its key ecosystem functions as both disperser and regulator of large-seeded plants, a reintroduction project was initiated at the Ibera National Park in northeastern Argentina. The ability of released individuals to find food is crucial, in particular when working with captive-bred animals, as long-term establishment of a self-sustaining population depends on their short-term ability to exploit wild food sources. Monitoring of feeding habits is usually conducted through behavioral observation, but in recent years DNA metabarcoding has emerged as an alternative for obtaining highly resolved data on diet composition. In this study we use a combination of both techniques to characterize the breadth and composition of the reintroduced macaws diet. In addition, we evaluate the efficiency of both direct field observations and metabarcoding of feces as techniques to assess diet composition. Individuals fed on a variety of plant species (n = 49) belonging to a broad phylogenetic spectrum (28 families). Dietary richness estimated by direct observation and metabarcoding was similar, though smaller than the combination of the two datasets as both techniques detected at least 15 species not recorded by the other method. While the total number of detected species was higher for observational data, the rate of species-detection per sampling day was higher for metabarcoding. These results suggest that a combination of both methods is required in order to obtain the most accurate account of the total diversity of the diet of a species. The ability of the reintroduced macaws to successfully exploit local food resources throughout the year indicates a good level of adjustment to the release site, an important step towards the creation of a stable, self-sustaining population of Red-and-green Macaws in Northern Argentina. RESUMENEn el transcurso de los ultimos dos siglos, el Guacamayo Rojo (Ara chloropterus) se ha extinguido en la Argentina. Buscando recuperar su rol ecologico tanto de dispersor como de depredador de semillas de gran tamano, se comenzo un proyecto de reintroduccion de la especie en el Parque Nacional Ibera, en la region noreste del pais. La capacidad para encontrar alimento por parte de los individuos liberados es crucial, particularmente cuando se trabaja con animales provenientes de condiciones de cautiverio, ya que el establecimiento de una poblacion autosuficiente a largo plazo dependera de la habilidad de estos para explotar fuentes de alimento silvestre a corto plazo. El monitoreo de habitos alimenticios se realiza usualmente a traves de observaciones comportamentales. Sin embargo, en los ultimos anos la tecnica del meta-codigo de barras de ADN ha surgido como una alternativa para la obtencion de datos de composicion dietaria con alto nivel de resolucion. En este estudio, utilizamos una combinacion de ambas tecnicas para caracterizar la amplitud y composicion de la dieta de los guacamayos reintroducidos. A su vez, evaluamos la eficiencia de la observacion directa y el codigo de barras genetico de heces como tecnicas para evaluar la composicion de la dieta. Los individuos se alimentaron de una amplia variedad de especies (n = 49), abarcando un amplio espectro filogenetico (28 familias). La riqueza dietaria estimada por observacion directa y por meta-codigo de barras genetico fue similar, aunque menor a la resultante de la combinacion de todos los datos ya que ambas tecnicas detectaron al menos 15 especies no registradas por el otro metodo. Mientras que el numero total de especies detectadas fue mayor para los metodos observacionales, la tasa de deteccion de especies por dia de muestreo fue mayor para el analisis genetico. Estos resultados sugieren que una combinacion de ambos metodos es necesaria para obtener la descripcion mas precisa posible de la diversidad dietaria total de una especie. La capacidad de los guacamayos reintroducidos para explotar recursos alimenticios locales a lo largo del ano estaria indicando un buen nivel de adaptacion al sitio de liberacion, un paso muy importante hacia el establecimiento de una poblacion de Guacamayo Rojo estable y autosuficiente en el norte de Argentina. Palabras claveAra chloropterus, Conservacion, Dieta, Frugivoria, Meta-codigo de barras, Guacamayo Rojo, Reintroduccion, Ecologia trofica LAY SUMMARYO_LIThe Red-and-green Macaw reintroduction project aims to restore this species to Argentina, where it is locally extinct. To assess if reintroduced macaws are successfully adapting to life in the wild, we studied their foraging habits at the Ibera National Park. Their food consumption was observed visually, and their feces were analyzed with molecular methods for traces of the consumed plants. C_LIO_LIMacaws fed from a large diversity of food items, exhibiting a flexible diet which varied with fruit availability in different months. A combination of both methods was required to obtain the most accurate account of the total diversity of the diet of a species. C_LIO_LIThe reintroduced macaws were able to successfully locate and exploit food resources throughout the year, indicating a good level of adjustment to the release site. C_LI