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

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
right, and depending on the direction of the bend, individuals also possess an accompanying leg
asymmetry; the leg opposite the curve in the mandible is slightly longer than the other leg (Mitchell
et al. 2005).
Hawai„i „ākepa are endemic to the Island of Hawai„i and are currently found in five disjunct
populations in „ōhi„a/koa forests in Hāmākua, Kūlani/Keauhou, Ka„ū, southern Kona, and Hualālai,
totaling approximately 14,000 ± 2,500 birds (95 percent CI) in 1980 (Scott et al. 1986). The highest
densities occurred in the southwestern portion of the Ka„ū Forest Reserve and in the Pua „Ākala
Tract of HFU (Scott et al. 1986), and these supported the largest populations, comprising 5,300 ±
1,500 (95 percent CI) birds and 7,900 ± 1,800 (95 percent CI) birds, respectively. The populations in
southern Kona and Hualālai were much smaller; approximately 660 ± 250 (95 percent CI) birds
combined (Scott et al. 1986), and apparently have declined since those surveys (Mitchell et al. 2005).
More recent surveys of the North Hāmākua area (1977-2000) estimate that approximately 8,300 (
144 SE) Hawai„i „ākepa occur in the study area (Camp et al. 2003). The HFU protects 72 percent of
the Hawai„i „ākepa population in the study area (approximately 6,000 „ākepa). A positive trend in
Hawai„i „ākepa density was observed for the 24-year study period (1977-2000); no changes in
densities were detected for the 14-year study period (1987-2000). The densities of Hawai„i „ākepa at
the HFU was 0.05 birds per acre (0.12 birds per ac, SD = 0.58) in the 1977 survey and 0.39 birds per
acre (0.97 birds per ac, SD = 2.03) for the 14-year study period. However, recent analysis of surveys
from 1987-2005 indicate that Hawai„i „ākepa densities are now stable or increasing at a mean rate of
2.3 percent per year (Hawai„i Forest Bird Database 2005).
In the central windward region of Hawai„i, Hawai„i „ākepa have historically demonstrated
contractions in distribution. Populations in the region are presently limited to a narrow band of high
elevation forest habitat in Kūlani-Keauhou and may be isolated from those in the Ka„ū and north
windward regions (Gorresen et al. 2005). At Kūlani-Keauhou, although the trend was not significant,
densities appear to have declined between the 1995-1998 and 2001-2003 survey periods (0.12 -
0.09 birds per acre). Hawai„i „ākepa densities averaged 0.19 birds per acre in the 1972-1975 survey
and 0.15 birds per acre in 1977. The declines in Hawai„i „ākepa may be related to loss of old growth
habitat at Keauhou Ranch, particularly in the early 1980s (Gorresen et al. 2005).
Hawai‟i „ākepa were not recorded in the Mauna Loa Strip and are no longer found in the „Ōla„a Tract
and „Ōla„a Forest Reserve. A regional population decline is also evident in the species‟ extirpation
from adjacent areas within the Hawai„i Volcanoes National Park (Gorresen et al. 2005).
At the HFU, Hawai„i „ākepa are locally common, and found in the montane wet „ōhi„a forest, mesic
koa/„ōhi„a forest, and montane dry koa/„ōhi„a māmane forest. Densities of Hawai„i „ākepa are highest
in upper elevation koa/„ōhi„a and „ōhi„a forests of high stature and closed canopy (Camp et al. 2003)
and occur in a gradient of population density, with a small core area of highest density in the Pua
„Ākala area and rapid decreases in density away from the core (Scott et al. 1986, Hart 2001). The
species was absent or occurred at low densities in heterogeneous habitats along the grass-forest
interface and in mid-elevation forest (Camp et al. 2003).
Several Hawai„i „ākepa have been regularly detected during bird surveys in the KFU since 1999
(USFWS 2008).
4-22 Chapter 4. Refuge Biology and Habitats