The ‘Apapane (Himatione sanguinea) is the most abundant and widespread honeycreeper, and the bird you’re most likely to see in Hawai’i’s rainforests. Like the ‘I’iwi, they’re red with black wings, but can be distinguished from their more attention-grabbing cousins by a smaller, black bill and a white vent. Also like ‘I’iwi, they pollinate ohia lehua, and are commonly seen strutting between blossoms in the forest canopy. Because they look and act so much like ‘I’iwi but don’t seem to be as popular, I have a bit of a soft spot for ‘Apapane.
These birds are the voice of the Hawaiian rainforest. They have an extensive repertoire of short songs that include whistles, chirps, and trills. One bird will start up a song, and then everyone within earshot will pick it up, creating an echoing chorus. The whirr of their wings as they fly between trees is another distinctive sound, and another characteristic they share with ‘I’iwi.
Juvenile ‘Apapane are abundant this time of year. They are grey or orangish (actually, they look superficially like ‘Elepaio, and have a similar erect-tail posture). They seem to have a wider behavioural repertoire than adults, as if they’re still figuring out their place in the world: a greater variety of calls and songs, and a tendency to venture further down below the canopy. They seem curious, and frequently approach birds of other species, only to be chased away.
It’s interesting that both of the main ohia pollinators—‘Apapane and ‘I’iwi—are red. I wonder if there’s a so-called receiver bias that drove sexual selection for plumage colour. That is, perhaps both species are extra-sensitive to red in their environment because it makes them good at finding the flowers on which they depend for food. Then, individuals that are similar in colour to these flowers might be more noticeable to the opposite sex and thus produce more young. Sexual selection then fixes red plumage in both species (or in their common ancestor; I think they are sister taxa—and incidentally, there’s one known case of hybridization between the two, resulting in an “apapiwi”).