'Ōma'o and 'ōlapa original

Original 9"x12" illustration.

‘Ōma’o (Myadestes obscurus) and ‘ōlapa (Cheirodendron trigynum).

‘Ōma’o is a thrush endemic to the Big Island. ‘Ōma’o, being primarily frugivorous, are crucial seed dispersers in native Hawaiian forests. The fleshy fruits produced by native plants such as ‘ōlapa, pilo, ōhelo, and others rely on ‘ōma’o for distribution. Although Hawai’i once had other native seed dispersing birds, ‘ōma’o is all that remains on Hawai’i Island (at least in wild, functionally-relevant numbers). Non-native birds are sometimes cited as being ecological replacements to fill in the lost roles of native seed-dispersing birds; unfortunately, it has been found that non-native seed dispersers (such as mejiro, bulbuls, leiothrix, etc.) preferentially spread non-native and invasive species, while ‘ōma’o spread more natives and a wider variety of natives.

‘Ōma’o, whose population is estimated at around 170,000, occupy about a third of their historic range. They are listed as vulnerable by the IUCN.

‘Ōlapa is an endemic member of the Araliaceae (ginseng) family occurring in mesic to wet forests throughout the Main Hawaiian Islands. The generic name, Cheirodendron, refers to the palmately compound leaves of this genus (“cheiros”, or hand, and “dendron”, for tree or wood). Their leaves produce a lovely fluttering sound in the breeze, which provided inspiration for some hula.

Threats to ‘ōma’o include habitat degradation, predation by rats, and deforestation—since ‘ōma’o are so closely tied to native fruit-bearing trees, invasive plant species are also a threat. Interestingly, ‘ōma’o appear to have some resistance to avian malaria, but malaria is not the only mosquito-transmitted disease that threatens native birds. Although ‘ōlapa are considered secure, habitat loss and loss of seed dispersers certainly does them no favors.