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

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
2005). However, individuals that have chronic malaria infections have had similar or higher
reproductive success than noninfected individuals (Kilpatrick et al. 2006).
Common „amakihi adults and nestlings are also susceptible to predation by mammal predators
(Lindsey et al. 1998). It has been suggested that predator control in mid-elevations may increase the
survivorship of malaria-resistant individuals, resulting in the persistence of native bird populations in
areas of active malaria transmission (Kilpatrick 2006, VanderWerf and Smith 2002).
4.5.3 ‘Apapane (Himatione sanguinea)
The „apapane is a small, crimson bird with black wings and tail. The immatures are like the adults,
except the crimson is replaced by a dull dark brown. The black bill of the „apapane is slightly curved.
„Apapane were formerly found on all forested islands in the Hawaiian Archipelago to sea level, but
are now restricted to higher elevations. Island population estimates based on Hawaiian Forest Bird
Surveys (1976-1981) are 1,080,000 ± 25,000 (95 percent CI) individuals on the Island of Hawai„i,
110,000 ± 9,000 individuals on Maui on Haleakalā (86 percent), 39,000 ± 5,000 individuals on
Moloka„i, 540 ± 213 individuals on Lāna„i, and 30,000 ± 1,500 individuals on Kaua„i. On Kaua„i,
populations declined after the 1992 hurricane, but have significantly increased since. The 2000
Kaua„i Forest Bird Survey estimated the population at 64,972 ± 2,014 (SE) individuals. „Apapane are
now rare or absent on Moloka„i and Lāna„i (Fancy and Ralph 1997, Mitchell et al. 2005).
Recent surveys estimate that approximately 255,900 ( 1,037 SE) „apapane occur in the north
Hāmākua study area. The HFU currently protects 29 percent of the „apapane population in the study
area (approximately 75,200 „apapane). An increase in „apapane density was observed for the 24-year
study period (1977-2000); no trends in „apapane densities were detected for the 14-year study period
(1987-2000). Mean density of „apapane in 1977 was 1.6 birds per acre and increased to 4.0 birds per
acre (SD = 5.61) for the 14-year study period within the HFU (Camp et al. 2003).
In the central windward region of Hawai„i, „apapane were ubiquitous and showed increasing or stable
trends at the higher elevations. At the Kūlani-Keauhou study area, „apapane were observed at an
average density of 6.7 birds per acre in 1972-1975, and 7.8 birds per acre in 1977. Densities
significantly increased from the 1990s to 2000s (9.9-11.5 birds per acre). At the Mauna Loa Strip,
„apapane occurred at stable densities of 0.1 birds per acre throughout the study period (Gorresen et
al. 2005).
At the lower elevation sites, „apapane numbers have declined. In the „Ōla„a study area, „apapane
densities declined from 7.8 birds per acre in 1977 and 2.8 birds per acre in 1994. The East Rift area
also exhibited significant declines from 4.1 to 2.6 birds per acre between the 1979-1993/1994 survey
periods (Gorresen et al. 2005).
„Apapane are found throughout HFU. Densities of „apapane are highest in upper-elevation koa-„ōhi„a
and „ōhi„a forests of high stature and closed canopy, and occur at low densities in grassland,
heterogeneous habitats along the grass-forest interface, and in mid- to low-elevation forest (Camp et
al. 2003). „Apapane are found at all elevations in the KFU (Atkinson et al. 2005), although densities
have not been estimated.
Chapter 4. Refuge Biology and Habitats 4-35