Foraging habitat preferences of a selective herbivorous bird, the Puna Rhea Rhea tarapacencis in the desert Puna, midwestern Argentina

MARINERO, N.V.; NAVARRO J.L.; MARTELLA M.B.

ACTA ORNITHOLOGICA

MUSEUM & INST ZOOLOGY

Lugar: Warszawa, POLAND; Año: 2020 vol. 55 p. 165 - 173

0001-6454

Habitat preference for herbivores is influenced by resource availability, which is most evident in desertecosystems. The desert Puna is a South American environment dominated by grassy steppes and, locally,grassy cushion plants associated with moist soil conditions form the habitat called "vegas". In this environment,Puna Rhea has a strongly selective foraging strategy towards species that are in low abundance but that exhibitlow contents of secondary compounds, fiber, or both. This contrasts with other generalist herbivores of aridenvironments which prefer plant species with high fiber content and are very abundant. We determined habitatuse by rheas in three habitat types: foothills, valley and vegas; and, evidence of their feeding habitatpreferences is provided. From 2011 to 2014, we estimated density of birds and environmental variables such astotal plant cover, and abundance of total food, preferred foods, and non-preferred foods. In particular, the density was estimated indirectly based on counting and collecting their feces in transects. We analyzed theeffect of the habitat type and environment variables on density; and compared the environmental variablesamong habitats. Puna Rheas used the three habitats, but fecal records were very scarce in vegas. The densitywas higher in foothills than in the valley (0.45 ind/km2 and 0.01 ind/km2, respectively), it increased withhigher abundance of the preferred foods and declined with increased non-preferred foods. The foothills waspreferred while it had the highest abundance of the preferred foods and the non-preferred foods were similarlyabundant in foothills and valley. The vegas had the highest total plant cover and the lowest abundance of allfood species consumed by rhea. Therefore, the abundance of preferred foods, which have the best nutritionalquality, represents a good predictor of habitat preference and, possibly, an essential resource during the life cycle of the Puna Rhea.