Does foraging competition drive plumage convergence in three look-alike Atlantic Forest woodpecker species?

FERNÁNDEZ JM; ARETA JI; LAMMERTINK M

Journal of Ornithology

Springer

Año: 2020 vol. 161 p. 1105 - 1116

2193-7192

Explaining the co-existence of sympatric and ecologically similar species is a central goal in ecology. In woodpeckers (Pici-dae), co-existence is frequently accompanied by plumage convergence. A particularly striking case concerns three wood-pecker species in the Atlantic Forest of South America: Robust Woodpecker (Campephilus robustus), Lineated Woodpecker(Dryocopus lineatus) and Helmeted Woodpecker (Celeus galeatus), which show a remarkable degree of plumage similaritythought to result from convergence due to interspecific social dominance mimicry (ISDM). We studied the foraging ecologyand interactions of these three species in old-growth forests and selectively logged forests to test the extent to which thesespecies differ in various aspects of their foraging ecology, and we examined whether particular foraging requirements mayhelp explain the association of the threatened Helmeted Woodpecker with mature forests. The species selected differenttree species, tree diameters, foraging heights, decay states of trees and decay states of substrates, resulting in marked nicheseparation among the three species. Proportionally, the Robust Woodpecker chiselled more, Helmeted Woodpecker usedmore probing and Lineated Woodpecker used more hammering. Helmeted Woodpecker was the only species that includedbamboos as foraging substrates, and it foraged more on dead wood than Lineated or Robust Woodpeckers, but mostly onsmall dead branches in live trees rather than standing dead trees. Foraging requirements are not the most likely factor explain-ing the association of Helmeted Woodpecker with mature forests. Limited resource and substrate overlap among the threewoodpecker species, lack of interspecific interactions, and rarity of the Helmeted Woodpecker do not match predictions ifthese species were conforming to a mimicry complex under the hypothesis of ISDM. Instead, plumage convergence may aidin interactions with third species, or impart advantages in intraspecific competition.