The ‘Anianiau (Magumma parva) is Kaua’i’s smallest honeycreeper. Along with ‘Elepaio, ‘Apapane, and ‘Amakihi, it’s one of the native species you’re almost guaranteed to encounter if you take a hike through the native forest in Koke’e State Park. It’s a tiny yellow-green bird (males tend to be golden yellow while females and juveniles are greener) with a long, slightly curved pink beak. Although their plumage is bright and their calls are noisy, these birds can be tricky to spot, as they often forage just below the canopy, obscured by leaves.
Their song is a trill that varies in length and speed; it may also be ornamented with extra chirps and whistles at the end. I’ve never heard it said, but I suspect their Hawaiian name is onomatopoeic and reflects this song. Their call is usually a double note, descending then ascending; it’s supposed to be diagnostic but is often imitated by ‘Akikiki, ‘Akeke’e, or ‘Amakihi (if you get the impression that birding by ear on Kaua’i is tricky, you’re right).
I’ve watched quite a few ‘Anianiau nests these past few months. During incubation, nests are quite easy to find, because females (who do most if not all of the incubating) beg for food from their mates, and do so loudly. But in the past few weeks, as many of the nestlings have fledged, there seem to be young birds everywhere, confounding my attempts to nest search. On the other hand, watching the new fledglings poke around and nearly fall out of trees is pretty entertaining.
Both male and female ‘Anianiau participate in nest building, and I’ve observed them stealing nesting material from other nests in their territory. These may be old nests, but I also watched a pair steal twigs from an ‘Akeke’e nest while the ‘Akeke’e were away looking for more material to add to it! (Incidentally, both those nests eventually failed, for reasons unknown.)