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

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
acquired malaria soon after being released, but survived; some required active veterinary support.
The remaining six surviving individuals were subsequently recaptured and reintegrated back into the
captive flock (USFWS 2003).
Currently, all „alalā are under captive propagation by the San Diego Zoological Society located at the
Keauhou Bird Conservation Center on the Island of Hawai„i and the Maui Bird Conservation Center
on Maui. This captive propagation and research program is a 20-year agreement to help the „alalā, as
well as 18 other Hawaiian forest bird species (USWFS 2008). Currently about 77 „alalā are in
captivity (ZSSD, unpubl.). Areas under consideration for repatriation of this species are listed below
in order of preference: (1) Southwest Ka„ū, (2) Keauhou-Kūlani, (3) Central Ka„ū, (4) Kapāpala,
(5) KFU, and (6) Kona Hema (Price and Jacobi 2007).
Historically, the „alalā was common in lower and middle-elevation mesic forests between 3,610-
4,920 ft on the western and southern side of the Island of Hawai„i (Giffin et al. 1987, Winter 2003).
When the species was relatively abundant, flocks of „alalā were observed to make extensive seasonal
movements in response to weather and the availability of the „ie„ie vine and other native fruit-bearing
plants (USFWS 2003).
The habitat with the highest breeding densities of „alalā during 1970-1982 was relatively undisturbed
„ōhi„a/koa forest; „alalā avoided disturbed forest where possible (Giffin et al. 1987). In addition, a
significant amount of protective understory cover appeared to be important to „alalā in avoiding
predation by „io (USFWS, unpubl.). The „alalā used the upper half of the canopy of mature trees for
their daily activities (Sakai et al. 1986) and fed on native and introduced fruits, invertebrates gleaned
from tree bark and other sites, and eggs and nestlings of other forest birds. Nestlings preyed upon
included the red-billed leiothrix and Japanese white-eye as well as four native species (Hawai„i
„amakihi, „i„iwi, „elepaio, and „apapane) (Sakai et al. 1986). Mice have also been noted in crow
droppings (Sakai et al. 1986). Nectar, flowers, and carrion are minor diet components. A strong
association was noted with „ie„ie, which formerly blanketed extensive tracts of mid-elevation mesic
and wet forest; however, „alalā were not observed in wet forests where „ie„ie is abundant (USFWS
2003).
The median home range recorded for the „alalā was 1,186 ac with a range of 146 - 3,598 ac. Nest
construction usually began in March and first clutches were laid in April. Recorded nests have been
predominantly in „ōhi„a, although other trees and „ie„ie vines may be used. All recorded nests have
been at elevations 3,280-5,905 ft. Known nest sites have been in areas with 24-98 in of annual
rainfall (USFWS 2003).
Because the population is small and confined to captivity, the „alalā is highly susceptible to
stochastic environmental, demographic, and genetic events. Inbreeding depression may also be
reducing the reproductive success of the captive population. Before the remaining „alalā were taken
into captivity, „alalā were threatened by predation from mammals, „io, avian diseases, and habitat
loss and fragmentation.
Rats and mongooses are known predators on „alalā eggs and nestlings. Cats are also suspected
predators on fledglings and adults (USFWS, unpubl.). Recent observations show that juvenile and
adult „alalā raised in captivity can be killed and eaten by „io in the wild (USFWS 2003).
4-28 Chapter 4. Refuge Biology and Habitats