Drepanidine movements in relation to food availability in subalpine woodland on Mauna Kea, Hawai'i

Flowers of the mamane tree (Sophoru chrysophylla) are the primary nectar source for Hawaiian honeycreepers in subalpine woodland on Mauna Kea Volcano on the island of Hawai‘i. Mamane seeds are the primary food resource of the endangered Palila (Loxioides bailleui), which is now restricted to subalpine woodland on Mauna Kea. The objectives of this study were to determine the patterns and relative scales of movements of the drepanidine community in relationship to food availability and tree density on leeward Mauna Kea. ‘I‘iwi (Vestiaria coccinea) and ‘Apapane (Himatione sanguinea) densities were related to mamane flower abundance. Palila densities were related to mamane pod abundance. These species also had higher densities in mamane woodland than in naiomamane woodland, unlike the more insectivorous Hawai‘i ‘Amakihi (Hemignathus virens) whose densities did not differ between woodland types. Palila and Hawai’i ‘Amakihi do not make movements on the same scale as ‘I‘iwi and ‘Apapane, whose densities changed by more than an order of magnitude. Ungulate eradication, grass reduction, tire management, and restored corridors of mamane woodland would benefit all drepanidines on Mauna Kea, particularly the Palila.