Diet composition of reintroduced Red-and-Green Macaws reflects gradual adaptation 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 Iberá National Park in northeastern Argentina. The ability of released individuals to find food is crucial, especially 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 compare the efficiency of both observational and molecular techniques to assess diet composition in a frugivorous bird. 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 DNA 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 DNA 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 bird species. The ability of 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.

Feeding ecology of the Red-and-green Macaw (Ara chloropterus; Gray 1859) in a habitat mosaic from Cerrado

“…In the present study, Redand-green Macaws ate 25 species, mainly their seeds, of which only eight achieved percentages ranging from 5 to 13.4% (Dipteryx alata) of their diet. On the other hand, in northeastern Argentina, direct observations detected 32 species in the diet of reintroduced Red-and-green Macaws, of which Psidium guajava consumed throughout the year, composed 60% of their diets (Volpe et al, 2022). This pronounced variability highlights the extent of dietary flexibility present in, at least part, Ara macaws.…”

“…Despite this, many macaw species have declined due to the increasing rarity of their main foods (Berg et al, 2007). In this respect, the Red-and-green Macaws' diet data are scattered across its current range (Roth, 1984;Santos, 2001;Lee et al, 2014;Volpe et al, 2022), remaining unknown for populations in Central Brazil, as well as their responses to fluctuations in food availability over time and space (Haugaasen and Peres, 2007). Knowledge of this dynamic is central, in addition to assessments of the diets of threatened macaws, to planning conservation efforts (Berg et al, 2007;Volpe et al, 2022).…”

Feeding Ecology of Reintroduced Golden Parakeets (Guaruba guarouba, Psittacidae) in a Protected Area in the Amazon Forest

“…We should note that we were unable to collect Croton matourensis for food training and supplementation. Psidium guajava, which is also known to be a favorite psittacine resource [38,39], was also never consumed in the wild but was offered daily in the supplemental feeders. The fact that some plants have not yet been explored by the released birds and that the accumulation curve was not completely flattened suggests that the diet of golden parakeets may be even richer, and that new species are yet to be discovered and incorporated.…”

Unravelling bird nest arthropod community structure using metabarcoding

“…Metabarcoding of bird feces has been used to determine the diet of species and disentangle bird-insect food webs (e.g., Rytkönen et al . 2019; Volpe et al . 2022).…”

“…Feathers are known to host several groups of parasitic arthropods (Fryderyk & Izdebska 2009) but can also serve as direct DNA source to confirm the identity of the nesting species. Metabarcoding of bird feces has been used to determine the diet of species and disentangle bird-insect food webs (e.g., Rytkönen et al 2019;Volpe et al 2022). However, given that nest sanitation is a widespread behaviour among birds (Guigueno & Sealy 2012), it is rather unlikely that sufficient quantities of feces are present in a nest at the end of the breeding season for a thorough dietary analysis.…”