Interspecific competition in Grallaria antpittas: observations at a feeder

We describe an aggressive interaction between the extremely rare Jocotoco Antpitta (Grallaria ridgelyi) and a close relative, the Chestnut-naped Antpitta (Grallaria nuchalis). Since first discovered in 1997, ecological information about the Jocotoco Antpitta has begun to accrue; however, much remains to be learned about this rare species in its limited native range. The observations described here advance our knowledge of the behavioral ecology of this elusive species and contribute more broadly to our knowledge of interspecific competition in antpittas in general. We show that in avian systems in which playback experiments fail to detect competition, competition may still be prevalent, in this case manifesting in a nonvocal, physically aggressive interaction. We also raise new questions about the potential for temporal variation in interspecific competition in grallariids due to increased resource demands during nestling provisioning.