Eastern spinebills are primarily nectar-feeders and use their highly-adapted, tubular beak to forage from tubular flowers. Their highly specialized beaks are hypothesized to be the result of a close co-evolution with the tubular flowers they feed upon. Eastern spinebills select flowers based on available nectar rather than size of the flower. Young are mainly fed on insects, differing from adults who depend on insects only during or prior to their breeding periods or when nectar availability decreases during winter.
These birds are most active during the day because the amount of nectar peaks at dawn and more insects are active at that time. Their nectar consumptions peaks in autumn, from August to October, mainly to store fat and increase their body mass to prepare for upcoming winter.
Animal Foods: insects
Plant Foods: nectar
Primary Diet: herbivore (Nectarivore )