Differentiation in foraging ecology between three sympatric woodpecker species of the Atlantic Forest in Argentina

The Helmeted Woodpecker (Celeus galeatus), a threatened species endemic to the Atlantic Forest, co-exists with two other woodpecker species of similar appearance: the Lineated Woodpecker (Dryocopus lineatus) and the Robust Woodpecker (Campephilus robustus). These are the three largest woodpecker species in the Atlantic Forest and they show a notable convergence in the colors and patterns of their plumages. However, Lineated Woodpecker (210 g) and Robust Woodpecker (261 g) are considerably heavier than Helmeted Woodpecker (130 g). We compared the foraging ecology of the three species in forests with and without selective logging. Out of 315 foraging observations, 257 observations came from 19 radio-tagged woodpeckers. Foraging substrate diameter was similar between Helmeted and Lineated Woodpeckers, but averaged more than double in Robust Woodpecker. Lineated and Robust Woodpeckers used trees of similar diameter at breast height whereas Helmeted Woodpeckers used trees with trunks that were significantly more slender. In foraging height, Robust Woodpecker foraged highest up followed by Lineated and then Helmeted Woodpecker. Helmeted Woodpecker foraged more on dead substrates. Helmeted Woodpecker included bamboos (Guadua trinii and Merostachys claussenii) as foraging substrates whereas only Lineated and Robust Woodpeckers were seen foraging on Paraná Pines (Araucaria angustifolia). There were only minor differences in foraging ecology in old-growth and selectively logged forests. In all, the three woodpecker species are well differentiated in foraging ecology. We will apply our findings of this foraging differentiation in upcoming works on species co-existence and plumage convergence, and on differentiation in responses to selective logging.