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

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
collected during the survey, only about 50 species have been identified. Although generalizations are
difficult based on the low number of species identified, arthropod diversity was lower than expected.
Arthropod surveys in other areas of the island found that the optimal range of native arthropods is
between 3,500-4,000 ft; thus, the majority of the Hakalau Unit is above the upper limit. During the
survey, increased diversity was observed at lower elevation sites (Howarth et al. 2003). Ongoing
arthropods surveys are being conducted by Goldsmith (2007), and by USGS-BRD (Banko and Peck)
at the HFU.
Arthropod surveys were conducted by Haines and Foote (2005) throughout the KFU. This study
occurred along four transects at elevations of roughly 2,500, 3,500, 4,500, and 5,500 ft. Several
trends were observed during the study. First of all, diversity among native target genera was highest
in the middle elevations of the KFU. In addition, native insect diversity generally decreases as
disturbance increased (occupied by ungulates) and as invasive insect populations increased (Haines
and Foote 2005).
Megalagrion (Odonata: Coenagrionidae)
Approximately nine species of native Hawaiian damselflies of the Megalagrion genus (Odonata:
Coenagrionidae) occur on the Island of Hawai„i. Megalagrion damselflies inhabit a wide range of
habitats including perennial stream, intermittent stream, rheocrenes (flowing seeps and springs), and
standing water ecosystems (Polhemus 1993, Polhemus and Asquith 1996). Immature damselflies (or
larvae) are typically aquatic, while some live in and under native plants. The adults feed on various
small insects captured using their spiny legs. Immature damselflies prey on small animals using their
extendable lower mouthpart (Polhemus and Asquith 1996).
Competition and predation from nonnative fish, frogs, and invertebrates is a primary threat to this
genus (Polhemus 1993). Fish predators include Poeciliids (Gambusia affinis, Poecilia reticulata, P.
latipinna, Xiphophorus helleri, and X. maculatus), as well as catfish, cichllids, and gobies. Alteration
and degradation of freshwater habitat has also contributed to species declines. Human modifications
that occurred during ancient Hawaiian times (taro lo„i and fishponds) and in the more modern times
(diversion systems, urban development, ground water pumping) have impacted Megalagrion habitat
(Polhemus and Asquith 1996).
Four damselflies species have been reported at the HFU and several additional species may also
occur. One of these, M. amaurodytum peles, is a species of concern that was found throughout the
Refuge in damp litter in axils of pa„iniu lilies (Astelia menziesiana) and „ie„ie (Freycinetia arborea)
(Howarth et al. 2003). The Pacific Hawaiian damselfly (M. pacificum), an endangered species, may
occur at the lowest elevations in the HFU. This damselfly species breeds in pools and streams. An
additional species of concern that breeds in streams, M. nigrohamatum, may also occur in the lower
elevations of the Refuge unit (Howarth et al. 2003).
Only a single Megalagrion species, the Beautiful Hawaiian damselfly (M. calliphya), is known at the
KFU. Two males were seen in a pool at the unit (Haines and Foote 2005). On Hawai„i Island, this
species is usually limited to areas above 985 ft. Male M. calliphya are mostly red with black strips,
while females have a green thorax (Polhemus and Asquith 1996). Adults can breed in standing water,
but prefer slow moving streams (Haines and Foote 2005).
4-50 Chapter 4. Refuge Biology and Habitats