Final Comprehensive Conservation Plan - U.S. Fish and Wildlife ...

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
Occurring primarily at elevations greater than 4,100 ft, „apapane occur in mesic and wet forests
dominated by „ōhi„a and koa. However, they are also known to migrate to lower elevations during
the summer. Occupied habitats also support kōlea, naio, and hāpu„u. Māmane is common in highelevation
foraging habitat (Mitchell et al. 2005).
„Apapane are primarily nectarivorous and the species is an important „ōhi„a polinator. Their
widespread seasonal movements, particularly from June-August, occur in response to „ōhi„a flower
availability (Macmillen and Carpenter 1980, Ralph and Fancy 1995). „Apapane also eat insects,
which they glean from outer foliage and twigs in the upper- and mid-canopy. Juvenile „apapane favor
arthropod prey more than adults possibly due to their higher protein/calorie requirements (Carothers
2001). „Apapane often forage in conspecific flocks, which can overwhelm „i„iwi and „ākohekohe,
which often defend flower-rich trees (Mitchell et al. 2005).
Birds in breeding condition may be found in any month of the year, but peak breeding occurs
February - June. The nest is usually a cup on a high terminal branch of „ōhi„a, but nests have also
been found in tree cavities and lava tubes, and on upper branches of koa, ilex, and Cibotium tree
ferns (Fancy and Ralph 1997).
„Apapane are susceptible to the same factors that threaten other native Hawaiian forest birds
including loss and degradation of habitat, disease, and predation by mammals. Disease is of
particular concern as „apapane have the highest prevalence of avian malaria of all native forest birds
(Samuel et al 2007, Atkinson et al. 2005, USFWS 2005). Because „apapane typically undergo
altitudinal migrations to follow „ōhi„a bloom, the species might be expected to receive higher
exposure to this disease than other more resident species such as „amakihi and Hawai„i „elepaio. Five
of eight (63 percent) juvenile „apapane experimentally infected with malaria suffered mortality
(Yorinks and Atkinson 2000). Individuals infected with avian pox also are more likely to be infected
with malaria. At low elevations of the KFU, malaria infection prevalence was recorded as high as
100 percent for „apapane. However, „apapane do breed in mid-elevation forests and have nesting
success similar to nests at higher elevation, suggesting that some individuals may be developing
disease resistance (Atkinson et al. 2005, Mitchell et al. 2005). The high mobility of „apapane coupled
with their high susceptibility to the parasite also make them exceptional reservoir hosts for the
parasite.
4.5.4 Hawai‘i ‘Elepaio (Chasiempis sandwichensis)
The Hawai„i „elepaio is a monarch flycatcher endemic to the Island of Hawai„i. The species has
highly variable plumage. The Hawai„i Island subspecies is morphologically variable and shows the
most dramatic differences between sexes compared to other subspecies. In general, adults are
primarily brown, with white and chestnut streaks below. Immature Hawai„i „elepaio are dull gray
brown, with gray below, and have buffy wingbars. Male and female „elepaio have a 2 year delay in
plumage maturation, meaning they do not acquire their adults plumage until they are 3 years old. As
the age of the bird increases, the amount of white increases at the throat, wing covert, rump, and tail.
Due to variations in plumage color, authorities have described additional subspecies on Hawai„i
Island (C. s. ridgwayi and C. s. bryani), but these are not widely accepted (VanderWerf 1999).
Currently, two additional subspecies (C. s. sclateri and C. s. ibidis) are recognized on the islands of
Kaua„i and O„ahu, respectively. Chasiempis sandwichensis originally colonized the State between
1.5-1.9 million years ago. Interisland song playbacks by VanderWerf (2007) suggest that the
4-36 Chapter 4. Refuge Biology and Habitats