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

FERNANDEZ, JUAN MANUEL; ARETA, JUAN IGNACIO; LAMMERTINK, MARTJAN

Journal of Ornithology

Springer Science+Business Media on behalf of the Deutsche Ornithologen-Gesellschaft

Año: 2020

2193-7192

Explainingthe co-existence of sympatric and ecologically similar species is a centralgoal in ecology. In woodpeckers (Picidae), co-existence is frequentlyaccompanied by plumage convergence. A particularly striking case concerns threewoodpecker species in the Atlantic Forest of South America: Robust Woodpecker (Campephilus robustus), LineatedWoodpecker (Dryocopus lineatus) andHelmeted Woodpecker (Celeus galeatus),which show a remarkable degree of plumage similarity thought to result fromconvergence due to interspecific social dominance mimicry (ISDM). We studiedthe foraging ecology and interactions of these three species in old-growth andselectively-logged forests to test the extent to which these species differ invarious aspects of their foraging ecology, and we examined whether particularforaging requirements may help explain the association of the threatenedHelmeted Woodpecker with mature forests. The species selected different treespecies, tree diameters, foraging heights, decay states of trees and decaystates of substrates, resulting in marked niche separation among the threespecies. Proportionally, the Robust Woodpecker chiselled more, HelmetedWoodpecker used more probing and Lineated Woodpecker used more hammering.Helmeted Woodpecker was the only species that included bamboos as foragingsubstrates, and it foraged more on dead wood than Lineated or RobustWoodpeckers, but mostly on small dead branches in live trees rather than standingdead trees. Foraging requirements are not the most likely factor explaining theassociation of Helmeted Woodpecker with mature forests. Limited resource andsubstrate overlap among the three woodpecker species, lack of interspecificinteractions, and rarity of the Helmeted Woodpecker do not match predictions ifthese species were conforming to a mimicry complex under the hypothesis ofISDM. Instead, plumage convergence may aid in interactions with third species,or impart advantages in intraspecific competition.