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

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
Nēnē graze and browse on the leaves, seeds, flowers, and fruits of at least 90 native and nonnative
grasses, sedges, composites, and shrubs. Composition of diet varies with location and habitat, and the
species may require a diverse suite of food plants. Nēnē disperse seeds and therefore play an
important ecological role, especially in influencing the species composition of early successional
plant communities. Historically, flocks moved between high-elevation feeding habitats to lowland
nesting areas (Mitchell et al. 2005, USFWS 2004).
Pairs mate for life, and nēnē have an extended breeding season. Eggs can be found in all months
except May-July, although the majority of birds nest between October-March. Nēnē nests consist of a
shallow scrape, moderately lined with plant materials and down. Pairs typically return to previous
years‟ nests sites, which are usually in dense vegetation (though this is highly variable); when
available, kīpuka (islands surrounded by lava flows) may be preferred. Breeding areas encompass a
variety of habitats including beach strand, shrubland, grassland, and lava rock, and occur at a range
of elevations. On the islands of Hawai„i and Maui, most nests are built under native vegetation such
as pūkiawe, „a„ali„i, and „ōhi„a. On Kaua„i, however, most nesting areas are dominated by nonnative
species, and nēnē often nest under Christmas berry, shrub verbena, and ironwood. The young remain
with their parents for up to 1 year (Mitchell et al. 2005, USFWS 2004).
Current threats to the nēnē include predation by mammals, exposure in high-elevation habitats,
insufficient nutritional resources for both breeding females and goslings, a lack of lowland habitat,
human-caused disturbance and mortality (e.g., road mortality, disturbance by human foot traffic),
behavioral problems related to captive propagation as well as habituation to humans in general, and
inbreeding depression (USFWS, unpubl., USFWS 2004). Predators of nēnē eggs and goslings
include dogs, cats, rats, pigs, and mongooses. Dogs, cats, and mongooses are responsible for most of
the known cases of adult predation (USFWS 2004). Nēnē have also been negatively impacted by
human disturbance by hikers, hunters, and outdoor recreationists. In recent years, nēnē have been
struck and killed by golf balls and vehicles (USFWS 2004).
Starvation and dehydration can also be major factors in gosling mortality. Approximately
81.5 percent of gosling mortality in Haleakalā National Park during the 1994-1995 breeding season
was due to starvation and dehydration (USFWS 2004). In 2005-2007, between 30-50 percent of the
goslings died due to dehydration and exposure at the HFU (USFWS, unpubl.). A lack of adequate
food and water also seems to be a limiting factor in Hawai„i Volcanoes National Park (USFWS
2004). A similar study (gosling telemetry) at HAVO in 1995 and 1996 identified dehydration and
starvation as the cause of death in the majority of gosling carcasses removed.
4.6.2 Koloa Maoli (Anas wyvilliana)
The koloa maoli is an endangered waterfowl endemic to the Hawaiian Islands. Federally listed as
endangered in 1967, the koloa maoli is a small, mottled brown duck with emerald green to blue
patches on their wings (speculums). Males are typically larger, have distinctive dark brown chevrons
on the breast and feathers, olive-colored bill, and brighter orange feet. Females are slightly smaller
and lighter in color. Compared to mallard ducks, koloa maoli are more secretive and about 20-
30 percent smaller.
The former range of the koloa maoli includes all the main Hawaiian Islands, except for the islands of
Lāna„i and Kaho„olawe. They are capable of spreading between islands and may be found up to
10,000 ft in elevation (Uyehara et al. 2007). Currently, the only naturally occurring population of
4-42 Chapter 4. Refuge Biology and Habitats