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

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
The largest population has long been thought to occur in the Hāmākua region. As of 2000,
approximately 1,600 ( 44 standard error (SE)) „akiapōlā„au were estimated to occur in the North
Hāmākua area. The HFU currently protects 50 percent of the „akiapōlā„au population in the study
area (approximately 800 „akiapōlā„au). In this Unit, a positive trend in „akiapōlā„au density was
observed for the 24-year study period (1977-2000); no trends in „akiapōlā„au densities were detected
for the 14-year study period (1987-2000). The density of birds for the 14-year study period in the
HFU was estimated to be 0.44 birds per acre (standard deviation (SD) = 0.39) (Camp et al. 2003).
In the Ka„ū/Kapāpala area, the population had reportedly decreased from an estimated 533-
544 individuals since the 1970s (Fancy et al. 1995), but a more recent and intensive survey revealed a
population in this region of more than 1,000 birds (USGS, unpubl.).
In the central windward region of Hawai„i (Figure 4-6), a 1972-1975 survey of Keauhou Ranch and
the Kīlauea Forest Reserve recorded an overall „akiapōlā„au density of 0.2 birds per acre. Subsequent
surveys in 1977, the 1990s, and 2000s detected densities of only 0.04 birds per acre. A 2002 survey
of the Upper Waiākea Forest Reserve directly north of the Kūlani-Keauhou study area did not record
„akiapōlā„au in areas in which they had been detected during the 1977 survey (Gorresen et al. 2005,
USFWS 2006b). The range of the „akiapōlā„au also no longer includes the „Ōla„a Tract and „Ōla„a
Forest Reserve from which the species were recorded as late as the 1960s. These results may indicate
the species‟ range has contracted upslope. Despite the apparent decline in „akiapōlā„au density, the
assessment of trend remains inconclusive. However, regenerating koa in degraded or deforested areas
on Kamehameha Schools‟ Keauhou Ranch and the Kapāpala Forest Reserve recently has been
observed to support relatively high densities of „akiapōlā„au (Pratt et al. 2001a, Pejchar 2004).
Three „akiapōlā„au remained in the māmane forest on Mauna Kea in 2000, but all three of these birds
are now gone. In the late 1970s, a relict population of 20 birds remained in the koa/„ōhi„a forests of
central Kona. „Akiapōlā„au were last detected in central Kona in the mid-1990s (USFWS 2006b) and
recent field surveys did not detect „akiapōlā„au in the area (USFWS 2008). The current status of the
birds in southern Kona is unknown (USFWS 2006b).
At the HFU, „akiapōlā„au are found in montane wet „ōhi„a and mesic koa/„ōhi„a forest and montane
dry koa/„ōhi„a/māmane forest. „Akiapōlā„au attained highest densities in the upper elevation in areas
with a koa component and heterogeneous habitats along the forest margins (Camp et al. 2003).
„Akiapōlā„au are positively associated with koa and closed canopy, and „akiapōlā„au density is
significantly and positively associated with „ōhi„a, high-stature forest and negatively associated with
grass and presence of banana poka. Recent observations of „akiapōlā„au have been in montane mesic
and wet forest dominated by koa and „ōhi„a or in subalpine dry forest dominated by māmane and
naio.
Males and females remain together in pairs most of the time. From the limited data available,
breeding occurs year-round (Pratt et al. 2001a). The home range size of both sexes varies from
approximately 12-100 ac. Territories are defended, and there is little evidence of daily or seasonal
movements. Habitat types influence the size of home ranges, with larger ranges occurring in open
forest and smaller ranges in koa plantation; home ranges vary from 56.8 ± 17.8 ac in open forest to
30.4 ± 17.8 ac in closed forests, and 28.9 ± 10.6 ac in young koa plantations. Furthermore, home
ranges overlapped more in koa plantations (41.2 percent), than in closed forest (22.6 percent) or open
Chapter 4. Refuge Biology and Habitats 4-19