Helmeted Woodpeckers roost in decay-formed cavities in large living trees: A clue to an old-growth forest association

LAMMERTINK, MARTJAN; FERNÁNDEZ, JUAN MANUEL; COCKLE, KRISTINA

Białowieża

Conferencia; 8th International Woodpecker Conference; 2019

The Atlantic Forest in southeastern South America is a biodiversity hotspotwith high species richness and high forest loss. Three large to mediumsizedwoodpecker species (Robust Woodpecker Campephilus robustus, 265g, Lineated Woodpecker Dryocopus lineatus, 209 g, and the old-growthspecialist, globally threatened Helmeted Woodpecker Celeus galeatus, 129g) coexist in the southern portion of the ecoregion, and show remarkableconvergence in plumage patterns and colouration, possibly driven byinterspecific interactions. We examined nest tree species, nest substrates,and timing of breeding, to assess differentiation in these niche dimensionsand to evaluate whether nesting ecology may be a factor explaining anassociation with mature forests in the Helmeted Woodpecker. Robust andLineated Woodpeckers excavated cavities in a wide diversity of nine andeight nest tree species, respectively, whereas Helmeted Woodpeckersspecialized narrowly on laurel trees (88% of nest cavities in two species ingenus Nectandra). Helmeted Woodpecker is further distinguished by amore frequent use of living, partially decayed trees (69%, vs 13% forRobust and 35% for Lineated) and by more frequent re-use of nest cavities(32%, vs 0% for Robust and 0% for Lineated). When nesting in selectivelylogged forest (vs. old-growth), Robust and Lineated Woodpeckers usedtrees withsmaller DBH (mean 48 vs 79 cm for Robust and 34 vs 60 cm forLineated) and Robust Woodpeckers excavated lower in trees (9 vs 17 m).Helmeted Woodpeckers selected nest trees with similar dimensions inboth environments (mean DBH 51 cm, height 9 m), indicating lesserflexibility. Helmeted Woodpeckers bred 20-23 days later in the year thanLineated and Robust Woodpeckers, potentially allowing them to avoidnesting near the two larger species. The narrow specialization of HelmetedWoodpecker on nesting in Nectandra trees of specific sizes and conditionsis a possible factor in making it more sensitive to selective logging effects.