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

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
growth of native species such as „ōhi„a, a preferred nesting tree (Griffin et al. 1998). Moreover, pigs
can facilitate the dispersal of nonnative plants and can significantly damage „ōhi„a seedlings by their
foraging activity. Strawberry guava in particular has the potential to invade and degrade up to
36 percent of the „io breeding range (Gorresen et al. 2008).
Introduced grasses have also altered natural fire regimes and ecosystem properties throughout much
of Hawai„i. Invasive fire-adapted species have increased the frequency, intensity, and extent of
wildfire, and contributed to declines in native tree cover and the expansion of grasslands in many
areas (Gorresen et al. 2008). Other possible limiting factors for the „io population include harassment
of nesting birds and shooting of adults. However, the level of harassment and shooting is difficult to
assess (USFWS 1984).
Little supporting evidence that environmental contaminants, avian pox, avian malaria, or Toxoplasma
gondii are limiting factors for the „io population currently exists (Griffin et al. 1998, Klavitter et al.
2003). There is also little evidence that „io fledglings are preyed upon by introduced mammals such
as rats, cats, and Indian mongooses (Griffin et al. 1998).
The „io was listed as endangered on March 11, 1967, and a final recovery plan was released in 1984
(Federal Register 2008a). The plan did not include specific delisting criteria; however, the primary
objective in the plan was to „„ensure a self-sustaining „io population in the range of 1,500-2,500 adult
birds in the wild, as distributed in 1983, and maintained in stable, secure habitat” (Federal Register
2008a). Because these targets were met, the Service proposed reclassification of the „io from
endangered to threatened status in August 1993, but this rule was not finalized. In August 2008, the
Service proposed to remove the „io from the Federal list of endangered and threatened wildlife. This
proposal is based on evidence that the species is broadly distributed throughout the Island of Hawai„i,
has been stable for at least 20 years, has large areas of habitat in protected status, and is able to nest
and forage in altered habitats (Federal Register 2008a). A post-delisting monitoring plan has been
drafted and public comments have been received. Delisting is currently under review.
4.5 Other Native Hawaiian Forest Birds
Native Hawaiian forest birds (nonlisted) found within the Hakalau Forest NWR are comprised of
four families: Fringillidae (honeycreepers), Monarchidae (monarch flycatchers), Turdidae
(thrushes), and Strigidae (true owls). The honeycreepers include the „i„iwi, common „amakihi, and
„apapane. The monarch flycatcher family is represented by the Hawai„i „elepaio, the thrush by the
„ōma„o, and the true owl by the pueo. Most of these bird species are most abundant in native
montane forests; however, the common „amakihi, Hawai„i „elepaio, and pueo are also found in
nonnative forests and can be common at lower elevations (Camp et al. 2003, Spiegel et al. 2006,
Woodworth et al. 2005, Mitchell et al. 2005).
Native bird populations have been closely monitored and information on changes in native forest bird
densities are available, particularly for North Hāmākua and the central windward region of Hawai„i.
Chapter 4. Refuge Biology and Habitats 4-31