(DRAFT) - Taxonomy
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
TAXONOMY
NAME - MILLERBIRD, NIHOA
OTHER COMMON NAMES - MILLERBIRD, NIHOA; BIRD, MILLER, NIHOA;BIRD, MILLER+, NIHOA; BIRD, MILLER+; MILLER-BIRD, NIHOA; BIRD, MILLER-, NIHOA; MILLERBIRD; WARBLER, WORLD and OLD
ELEMENT CODE -
CATEGORY - Birds
PHYLUM AND SUBPHYLUM - CHORDATA,
CLASS AND SUBCLASS - AVES,
ORDER AND SUBORDER - PASSERIFORMES,
FAMILY AND SUBFAMILY - MUSCICAPIDAE,
GENUS AND SUBGENUS - ACROCEPHALUS,
SPECIES AND SSP - FAMILIARIS, KINGI
SCIENTIFIC NAME - ACROCEPHALUS FAMILIARIS KINGI
AUTHORITY -
TAXONOMY REFERENCES -
COMMENTS ON TAXONOMY -
Nihoa Millerbird
Acrocephalus familiaris kingi (Wetmore, 1924)
KINGDOM: Animal GROUP: Bird
PHYLUM: Chordata CLASS: Aves
ORDER: Passeriformes FAMILY: Muscicapidae
The Nihoa millerbird (Acroscephalus familiaris Rothschild, 1892
kingi Wetmore, 1924) has been described as "dark gray-brown above and
buffy-white below, with a thin dark-colored bill" (07,38). The
original type description by Wetmore in 1924 considered the dorsal
plumage to be dark olive and olive brown, with grayish margins on the
feathers; the wings and retrices chaetura drab; the throat, breast,
and abdomen whitish with some light grayish olive wash on the sides;
buffy brown flanks; and the beak, tarsus, and toes blackish (02).
Sexes are similar. The Nihoa millerbird is a small bird, like its
close relative the Laysan millerbird which was once reported to be
4 and 1/2 inches in length (08). In recent years, one male Nihoa
millerbird with abnormal (leucistic) plumage was seen on Nihoa (09).
The Nihoa millerbird is closely related to the now extinct Laysan
millerbird, Acrocephalus familiaris familiaris Rothschild 1892. The
Laysan millerbird, an endemic of Laysan Island, was collected by
Taxonomy - 1 (DRAFT) - Taxonomy
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
Palmer and Munro in 1891, and described by Rothschild in 1892 (01,06,
11). It was called a "millerbird" due to its intense feeding on the
several Laysan moths locally known as "millers" (08,11). The original
genus and species designation for the Laysan millerbird was Tatare
familiaris (01,04,13). Due to serious habitat disturbances, the
Laysan millerbird became extinct between 1915 and 1923 (06,11). The
Nihoa millerbird, an endemic of Nihoa Island, was first discovered by
the Tanager expedition in 1923 and described by Wetmore in 1924 (02).
The Nihoa millerbird had remained undiscovered by an earlier
expedition which had not landed on Nihoa due to the difficult landing
(03). Wetmore named this new millerbird from Nihoa "Canopoderas
kingi" and acknowledged its relatedness to the (recently extinct)
Laysan millerbird, which he referred to as Conopoderas familiaris
(02). In 1928, Delacour (31) also referred to the Nihoa millerbird as
Conopoderas kingi, but in 1941 Vanderbilt and de Schauensee called it
Conopoderas familiaris kingi (05). At the present time, although some
persons consider the Nihoa millerbird to be a separate species rather
than subspecies (Acrocephalus kingi versus Acrocephalus familiaris
kingi), it is usually referred to as the latter (03,04,07,38). The
1986 IUCN Red List of Threatened Animals lists the Nihoa millerbird
under the scientific name Acrocephalus kingii. Common names which
have been used for the Nihoa millerbird are: Nihoa miller bird (03,
17,30) and the Nihoa miller-bird (02), as well as general references
to it as an old world warbler or just millerbird (02,31).
Clapp, Kridler, and Fleet (10) and Banko (12) both contain lists
and locations of Nihoa millerbird specimens; Ely and Clapp (11) as
well as Banko (12) contain lists and locations of Laysan millerbird
specimens. The Nihoa millerbird type specimen is catalog No. 287,888
in the National Museum of Natural History in Washington, D.C. (02,12).
Additionally, there are Nihoa millerbird specimens in the Bishop
Museum in Honolulu, Hawaii, and at least one specimen in the museum at
Brigham Young University-Hawaii in Laie, Hawaii (35).
Photos or plates of Laysan millerbirds appear in Rothschild (13),
Fisher (25), and Bailey (37). Photos of Nihoa millerbirds can be
found in Sincock and Kridler (06) and USFWS 1985 (15). Marshall (14)
contains a photo of a Nihoa millerbird on a nest. Sincock and Kridler
report that in 1968, film footage was taken of a Nihoa millerbird
on a nest, and also a tape recording was made of Nihoa millerbird
singing (06). Tapes of songs and call notes of Nihoa millerbirds have
also been made by Sheila Conant and copies have been deposited at the
sound library at Florida State Museum in Gainesville, Florida (35).
Taxonomy - 2 (DRAFT) - Status
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
STATUS
Coded Status
E: Federal Endangered
COMMENTS ON STATUS -
U.S. STATUSES AND LAWS:
The Nihoa millerbird (Acrocephalus familiaris kingi) has been
designated Endangered pursuant to the Endangered Species Act of 1973
(50 CFR 17.11; P.L. 93-205, 87 Stat. 884; 16 U.S.C. 1531-1540), as
amended. The subspecies has this status wherever found including the
State of Hawai`i.
This subspecies is protected by the Lacey Act (P.L. 97-79, as
amended; 16 U.S.C. 3371 et seq.) which makes it unlawful to import,
export, transport, sell, receive, acquire, or purchase any wild animal
(alive or dead including parts, products, eggs, or offspring):
(1) in interstate or foreign commerce if taken, possessed,
transported or sold in violation of any State law or
regulation, or foreign law; or
(2) if taken or possessed in violation of any U.S. law,
treaty, or regulation or in violation of Indian tribal law.
It is also unlawful to possess any wild animal (alive or dead
including parts, products, eggs, and offspring) within the U.S.
territorial or special maritime jurisdiction (as defined in
18 U.S.C. 7) that is taken, possessed, transported, or sold in
violation of any State law or regulation, foreign law, or Indian
tribal law.
RESPONSIBLE FEDERAL AGENCIES:
USFWS -Responsible for the management/recovery, listing, and
law enforcement/protection of this species.
All Federal agencies have responsibility to ensure that any
action authorized, funded, or carried out by that agency is not likely
to jeopardize the continued existence of the species or result in the
destruction or adverse modification of Critical Habitat (50 CFR 402),
and to utilize their authorities to carry out programs for the
conservation of the species.
STATE STATUSES AND LAWS:
STATE: Hawai`i
DESIGNATED STATUS: Endangered
ADMINISTRATIVE AGENCY: Dept. of Land and Natural Resources
STATE STATUTE: Hawai'i Revised Statutes, Chapter 195D.
Status - 1 (DRAFT) - Status
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
IUCN lists the Nihoa millerbird (Acrocephalus kingii) as rare in
1977, and 1986 IUCN Red List of Threatened Animals. The Convention
on Nature Protection and Wildlife Preservation in the Western
Hemisphere Annex lists the species with the scientific name
Acrocephalus kingi (1970).
ECONOMIC STATUSES:
The species is of minimal economic importance. Because of its
limited distribution (Nihoa Is.) and the difficulty of access it does
not have significant recreational non-consumptive (i.e. bird watching)
value.
67/03/11:32 FR 4001 - Original listing
69/03/08:34 FR 05034/05035 - Republished list
70/08/25:35 FR 13519/13520 - Proposed relisting
70/10/13:35 FR 16047/16048 - Final ruling on previous list
74/01/04:39 FR 01171/01178 - Updated list
76/09/30:41 FR 43340/43358 - Updated list
76/10/27:41 FR 47180/47198 - Updated list to correct errors
77/07/14:42 FR 36420/36431 - Updated list
78/12/11:43 FR 58030/58048 - Updated list
79/05/21:44 FR 29566/29577 - Notice of status review
80/05/20:45 FR 33768/33781 - Updated list
83/07/27:48 FR 34182/34196 - Updated list
85/07/22:50 FR 29901/29909 - Notice of Review
Status - 2 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
TERRESTRIAL
COASTAL
LAND USE -
Mixed Rangeland
Streams and Canals
Bare Exposed Rock
Mixed Barren Land
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Riverine, intermittent SB1
Riverine, upper perennial SB1
COMMENTS ON HABITAT ASSOCIATIONS -
The Nihoa millerbird is endemic to the steep, rocky, shrubby
island of Nihoa (in the past sometimes called "Bird Island" or "Moku
Manu" (02)) in the Northwestern Hawaiian Islands National Wildlife
Refuge (04,07). Nihoa is approximately 156 acres in size (07). Only
80 to 100 acres is considered to be suitable Nihoa millerbird habitat
(20), although millerbirds are found throughout the vegetated area
(21). The Northwestern Hawaiian Islands Passerines Recovery Plan (01)
lists the present essential habitat for the Nihoa millerbird as: "All
land to the mean lower low water line on Nihoa Island (approximately
62 ha (153 acres)). Sincock and Kridler stated that the preferred
habitats for Nihoa millerbirds appeared to be near the fresh water
seeps, under the endemic palm Pritchardia and on top of Nihoa at
Miller Flat; however, they report seeing Nihoa millerbirds throughout
the island (06).
Nihoa millerbirds are secretive and difficult to observe (06,22).
They prefer dense low vegetation, and are usually encountered in dense
cover near the ground (02,04,06,10), especially in Chenopodium and
Sida (07,15,17,21,22,23). Not surprisingly, Chenopodium and Sida
provide the first and third highest percentage of cover, respectively,
for the entire island of Nihoa (20).
In terms of percent cover, Nihoa is 20 percent rock, 12 percent
bare soil, 20 percent Chenopodium oahuense, 19 percent Solanum
nelsoni, 13 percent Sida fallax, 10 percent Eragrostis variabilis, 2
percent Sesbania tomentosa, and 4 percent other plants (20).
Chenopodium, Solanum, Sida, and Eragrostis are also the most abundant
four of the approximately 25 plant species which have been reported
for Nihoa (21,24). Other principal species include (in descending
order of abundance): Panicum torridum, Portulaca villosa, Euphorbia
celastroides, Sesbania tomentosa, and the endemic palm, Pritchardia
remota. Less common plants are: Portulaca lutea, Schiedea
verticillata, Sicyos sp., Ipomoea indica, Ipomoea pes-caprae,
Heliotropium curassavicum, Setaria verticillata, and Amaranthus
brownii. The mixture of plants has been described as "heterogeneous"
(06), although some zonation (Eragrostis along the ridges, Euphorbia
along cliff edges, and Pritchardia in the valleys) apparently exists.
Eragrostis grasslands are not considered very good habitat for
Nihoa millerbirds, probably because Eragrostis does not have the high
densities of insects (i.e. Nihoa millerbird food) which are found
elsewhere (21).
The majority of Nihoa millerbird nests are located in
Habitat Associations - 1 Chenopodium, but Sida and Solanum are also used (06,10,21). In
addition, Chenopodium and Solanum plants have numerous insects on them
and are probably the most important food source substrate (18,20,24).
If the vegetation, insect fauna, or fresh water seeps were
disturbed, there could be adverse impacts on the ability of Nihoa
millerbirds to forage and find cover, or nesting sites.
Rainfall on Nihoa is probably similar to that on French Frigate
Shoals, which varied from 26 to 54 inches per year during 1967 to 1974
(06,24).
Average monthly temperatures are also probably similar to French
Frigate Shoals, where it is usually 75 degrees F +/- a few degrees.
On Nihoa itself, Sincock and Kridler (06) recorded maximum and minimum
temperatures of 88 to 54 degrees F during their visits from 1969
through 1974.
The elevation of Nihoa rises from sea level to approximately 900
feet at Miller's and Tanager Peaks on either end of the island (09).
It is a difficult island to land a boat on, due to its rocky shore
(06); steep cliffs are on three of its four "sides."
Other specific environmental or life stage requirements are not
currently known.
Habitat Associations - 2 (DRAFT) - Food Habits
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
LIFESTAGE FOOD FOOD PART
General Arthropods
Food Habits - 1 (DRAFT) - Environment Associations
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Aquatic Features: Springs [flowing]
G Coastal Features: Rocky offshore islands
G Coastal Features: Vegetated offshore islands
G Terrestrial Features: Loess Hills
Environment Associations - 1 (DRAFT) - Life History
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
LIFE HISTORY
FOOD HABITS:
Nihoa millerbirds are insectivorous, with terrestrial arthropods
being virtually the entire diet (20,21,23). No plant remains have yet
been found in their feces (21). Conant saw Nihoa millerbirds
frequently eat the insect Nysius, which were abundant on the plant
Chenopodium oahuense, and the flea beetle Epitrix, which was numerous
on Solanum. Both of these plants had great numbers of insects on them
and are probably the most important food source substrate, although
Sida and Eragrostis are also a source of insects (18,20,24). As their
name implies, Nihoa millerbirds also feed on "miller" moths of all
stages (02,21); moth larvae parts have been found in Nihoa millerbird
fecal samples (21). Nihoa millerbirds have been reported to forage for
small insects under sticks or litter; one was seen feeding on flies
from a dead bird carcass (22).
Sincock and Kridler (06) reported that newly captured Nihoa
millerbirds would not eat papaya, banana, or boiled egg yolks which
were offered to them, although they would eat flies attracted to
papaya smeared on the cage and also ate 6 to 10 moths per day when
offered to them. All of the captive birds were said to freely take
fresh water from dishes.
The extinct Laysan millerbird from Laysan (Acrocephalus
familiaris familiaris) was also entirely insectivorous, feeding on
insects, moths, flies, small beetles, and caterpillars (03,06,11).
The abundance of terrestrial arthropods, which is the sole source
of Nihoa millerbird food, is linked directly to the phenology of the
vegetation on Nihoa, which is in turn a result of seasonal changes in
weather or other environmental factors (21). Kramer and Beardsley
(18) suggested that the vegetation changes due to a drought, for
example, would cause a lower population of plant-feeding insects and
therefore less food for the Nihoa millerbird.
HOME RANGE/TERRITORY:
The only work on Nihoa millerbird territoriality appears to be
that done by Conant (09,20,21). She reports that the birds seem to be
sedentary and probably remain on the same territories throughout their
lives (20). Using two different techniques to evaluate territory
size, Conant reported that the average territory size was between 0.5
and 2.3 acres, but that 2.3 acres was probably too high, and 0.5 to
1.0 acres per territory was more reasonable, especially considering a
population estimate of 300 birds (20,21,32). Evidence for a high
degree of territory faithfulness is demonstrated by the repeated
resighting of the same color-banded male Nihoa millerbird in August
1981 and April 1983 within 50 m (165 ft) of his original June 1980
banding site (09). Sincock and Kridler (06) also report an August
1968 recapture of a banded Nihoa millerbird in the "same area" on
Nihoa (Miller Flat) where it had originally been banded in September
1964.
Sincock and Kridler (06) indicated that newly captured Nihoa
millerbirds, unlike Nihoa finches (Telespyza ultima), fought with one
another when put in a single cage, and later had to be put in separate
cages.
Life History - 1 (DRAFT) - Life History
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
Kramer and Beardsley (18) reported that in June they commonly saw
male Nihoa millerbirds singing from the tops of larger bushes and that
they appeared to be guarding nests or territories.
PERIODICITY:
Although no published reports of Nihoa millerbird periodicity
were located, several references mentioned crepuscular activity in the
closely related but now extinct Laysan millerbird (11,25,26). Fisher
(25,26) recounted that Laysan millerbirds on Laysan retired to shade
of bushes or tall grass tussocks in the hot part of the day. Ely and
Clapp (11) reported that Laysan millerbird activity on Laysan Island
peaked in the morning and late afternoon, but in the warmer part of
the day Laysan millerbirds took shelter in the bushes and grass.
MIGRATION PATTERNS:
Nihoa millerbirds are a non-migratory species (04). They are
endemic residents of Nihoa Island in the Hawaiian Islands National
Wildlife Refuge (07).
COVER/SHELTER REQUIREMENTS:
There have not been any studies of Nihoa millerbirds which
specifically define cover/shelter requirements.
The plants Chenopodium oahuense, Solanum nelsoni, and Sida
fallax, which are the major percent of the vegetative cover on Nihoa,
provide foraging substrate, nesting sites, and cover for the Nihoa
millerbird (06,07,10,15,17,21,22,23).
Based on a sample size of 35, it appears that the average height
of a Nihoa millerbird nest above the ground is 33 cm (13 in) (21);
therefore, some vegetation of greater than 33 cm in height is
necessary.
REPRODUCTIVE SITE REQUIREMENTS:
The first active Nihoa millerbird nest was found on Nihoa in
June, 1962 (14). Since then, approximately forty Nihoa millerbird
nests have been discovered and reported on in the literature; the
majority of these nests were located in Chenopodium, but Sida and
Solanum were also used (06,10,21). Nihoa millerbirds seem to prefer
dense shrubs for nest cover (07,10,21,23). Based on a sample size of
35 nests, the average height above the ground was 33 cm (13 in) (21).
Nests are composed of grass and feathers, including great frigatebird
(Fregata minor) as well as Nihoa millerbird feathers (06).
On Laysan Island, the closely related but now extinct Laysan
millerbird (Acrocephalus familiaris familiaris) is reported to have
nested a couple of feet above the ground in tall grass clumps of
Eragrostis along the lagoon (11,36). The abundance of the grass
Eragrostis on Laysan and the paucity of it on Nihoa probably accounts
for the apparent difference in nest site preference between the Nihoa
millerbird and the extinct Laysan millerbird. Laysan millerbird nests
were reportedly made of rootlets, grass, and white albatross feathers
(03,11).
REPRODUCTIVE CHARACTERISTICS:
The breeding season for the Nihoa millerbird probably spans four
Life History - 2 (DRAFT) - Life History
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
to five months; Conant believes that the beginning of the breeding
season may be any month from January to May (21). Breeding has been
recorded from February to August (06,14,18,21). Sincock and Kridler
(06) noticed that there were breeding peaks in May and June. Since
nest building takes 1 1/2 to 2 weeks (21), it is possible that
breeding can occur in January, as the Recovery Plan suggests (07).
Clapp, Kridler and Fleet (10) though that the breeding season probably
spanned from February through early September. Conant thinks that the
variability in the onset of breeding is possibly due to the variable
vegetation phenology (and hence insect food) caused by differences in
rainfall or other environmental factors (21).
For the closely related but now extinct Laysan millerbird from
Laysan, eggs were seen in May and June (11); Dill and Bryan (36)
reported Laysan millerbird eggs and young in late spring and early
summer.
Marshall (14) reported that "two birds" at one nest incubated the
egg, although whether these two birds were the pair, or an adult and a
nest helper, is unclear. Conant (unpublished data) also recorded
incubation behavior at one nest, noting that two birds took turns
incubating (35).
Nihoa millerbird clutches of one (06,14,18), two (06), and three
eggs (35) are reported; the average is probably two eggs (07). For
the extinct Laysan millerbird, clutches of two to three were reported
(03,06,11). Conant (unpubl. data) (20) recorded an incubation period
of 17 days in one two-egg clutch, wherein only one egg hatched (35).
The appearance of Nihoa millerbird eggs seems to be variable:
descriptions range from pale blue eggs with brown splotches to white
eggs with sepia brown to black spots (06). Similar variability was
reported for the eggs of the now extinct Laysan millerbird (25).
Age of sexual maturity, minimum and maximum breeding age,
receptive period of the female, average number of reproductive periods
in a year, mating reltionships, duration of pair bond, and incubation
length are unknown.
PARENTAL CARE:
Nihoa millerbirds are an altricial species; young are hatched
naked (06). Length of time from hatching to independence, nest
guarding behavior, duration of family bond, and other aspects of
parental care are apparently not known.
POPULATION BIOLOGY:
The current limiting factors for Nihoa millerbirds are probably
adverse weather (e.g. drought, storms), variations in the insect food
supply, and the limited amount of nesting territories. This
conclusion is partly based on the fact that there is only about 80 to
100 acres of suitable Nihoa millerbird habitat on Nihoa Island (which
is a total of 156 acres in size) (20,21). The population appears to
fluctuate from year to year (see below); it is possible that the
carrying capacity of Nihoa itself fluctuates and is the cause of some
of these population fluctuations (07). In addition, weather (e.g.
hurricanes) may cause stochastic population changes. There is also
evidence that sampling techniques cause apparent fluctuations in
population estimates. In 1980 Conant, Collins and Ralph (32) used
Life History - 3 (DRAFT) - Life History
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
five different methods to estimate the Nihoa millerbird population:
estimates ranged from 133 +/- 53 to 659 +/- 205 (95 percent
Confidence Limits). Only the variable circle plot method did not
seem to have an observer effect; this was judged to be the best
method. The total population estimate from the variable circle plot
method was 287 +/- 41 birds. The first population estimate ever
published for Nihoa millerbirds was made by Wetmore in 1924; he
estimated that in 1923 there were about 100 Nihoa millerbirds (02).
Other population estimates over the years have ranged from a low 41
to a high of 659 (06,15,17,22,27,28,29,32,33). The precision of
these estimates is extremely variable.
The maximum carrying capacity for Nihoa has been estimated at
approximately 600 birds (07,15,21,32).
In 1903, Fisher (25) stated that the (now extinct) Laysan
millerbird on Laysan Island was one of the most abundant of the four
endemic land birds; three of the four endemic Laysan land birds are
now extinct.
No information on survival rate, mortality rate, rate of
increase, sex ratio, recovery potential, turnover rate, or longevity
for Nihoa millerbirds was located during a literature review.
SPECIES INTERRELATIONSHIPS:
The Nihoa millerbird is insectivorous (20,21,23) and is therefore
a predator completely dependent upon many terrestrial arthropods as
its prey. Conant has seen the Nihoa millerbird frequently eat the
insect Nysius and the flea beetle Epitrix, which are numerous on
Chenopodium and Solanum plants, respectively (20). Although they are
insectivorous, Nihoa millerbirds are totally dependent upon Nihoa's
vegetation, since seasonal changes in weather or other environmental
factors directly impact the vegetation, and hence the plant-feeding
arthropods upon which the Nihoa millerbird feeds (21). The Nihoa
millerbird has also been reported to feed on flies, moths, and other
insects (06,21,22).
OTHER LIFE HISTORY DESCRIPTORS:
Nihoa millerbirds are reported to not be hardy cage birds (06,
34). They have never been translocated to any other area (07),
although it has been discussed (06,07,20,21,34). In the past, both
Necker Island and Laysan Island have been suggested as possible
translocate sites for Nihoa millerbirds (06,20,21); Necker has been
shown to be an unsuitable translocate site due to the lack of suitable
habitat as well as the scarcity of terrestrial arthropods which are
the Nihoa millerbirds' only food source (21).
Life History - 4 (DRAFT) - Management Practices
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Controlling/Restricting Boating Activities
Beneficial Restricting/regulating human disturbance of populations
Beneficial Controlling/Removing Nonnative Vegetation
Beneficial Stocking captive-reared wild-strain animals
Beneficial Disease Control Measures
Beneficial Controlling/Removing Invertebrates
Beneficial Controlling/Removing Exotic Vertebrates
Adverse Incidental Capturing/Killing
Existing Incidental Capturing/Killing
Adverse
Existing
Adverse Food Supply Reduction
Existing Food Supply Reduction
Adverse Low Gene Pool
Existing Low Gene Pool
Adverse Disease
Existing Disease
Adverse Parasites
Existing Parasites
Adverse Predation
Existing Predation
Adverse Soil compaction by heavy equipment in mine areas
Existing Soil compaction by heavy equipment in mine areas
Adverse Exotic/Feral/Introducted Species
Existing Exotic/Feral/Introducted Species
Adverse
Existing
Adverse Vegetation Composition Changes
Existing Vegetation Composition Changes
Adverse Fire
Existing Fire
COMMENTS ON MANAGEMENT PRACTICES -
The Nihoa millerbird is endemic to Nihoa Island (also
obsoletely called "Moku Manu" or "Bird Island" (02)), a small, steep
island of approximately 156 acres reaching a maximum elevation of
about 935 feet (06,07). The very small size and fragility (e.g.,
susceptibility to fire and impacts of introduced organisms) of the
historic range was one of the main factors used in the determination
of the Nihoa millerbird's endangered status (06,15). In addition, the
Nihoa millerbird population estimates have always been extremely low
(06,15,17,22,27,28,29,32,33).
One impact on the Nihoa millerbird has been human disturbance.
In prehistoric times, polynesians inhabited Nihoa Island; rock home
sites, temple sites, and agricultural terraces remain as evidence of
this early occupation (06,24) and undoubtedly reduced habitat and/or
food. Also, in 1885 a picnic expedition to Nihoa started a brush fire
which "must have killed off many birds" (16).
Management Practices - 1 (DRAFT) - Management Practices
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
Another impact has been unauthorized military use of Nihoa (as
well as other remote islands) (17,18,19), although in most recent
years this has not been reported as a problem. Unfortunately, some of
the non-native weed and insect species on Nihoa probably arrived there
in this way on equipment and clothing (18).
The factors which presently threaten the Nihoa millerbird
population on Nihoa are:
- Human activity (06);
- The introduction of pest plants or animals (e.g., aggressive
weeds, predators, or destructive insects and parasites) via
natural or man-made causes (06,18). Pest plants may replace
essential cover; the abundance of terrestrial arthropods,
which is the sole source of Nihoa millerbird food, is linked
directly to the phenology of the vegetation on Nihoa, which
is in turn a result of seasonal changes in weather or other
environmental factors (21). Kramer and Beardsley (18)
suggested that the vegetation changes due to a drought, for
example, would cause a lower population of plant-feeding
insects and therefore less food for the Nihoa millerbird.
Introduced animals may prey upon the Nihoa millerbird,
compete with them for food and cover, or be a disease vector
(e.g., insects);
- Unauthorized and emergency landings, especially those which
may result in successful introductions (06,17,18,19);
- Fire (06,16);
- Avian diseases, which could arrive either naturally or due
to human activities (06,07). Most of Hawaii's native
passerine birds have been shown to be especially susceptible
to avian diseases, probably due to their long history of
insular isolation (39); and
- Weather (e.g. hurricanes or droughts) which destroys or
alters habitat and food sources (06).
In the case of the Nihoa millerbird, the limited size of the
native range, the fragility of the ecosystem (06,15), and the small
population size (06,07,10,32) are the reasons for its endangered
status.
Future threats to Nihoa millerbirds in the wild are the same as
the present threats which are listed above, except that unauthorized
landings will increase if the fishing industry expands in the waters
around the Northwestern Hawaiian Islands. The increase in
unauthorized landings will increase the likelihood of accidental
introduction of pest plants and animals (e.g. due to seeds on
clothing, rats or insects from landed boats). Also, as the number of
pest plants and insects and also avian diseases increase throughout
all the Hawaiian Islands in the future, the frequency of "natural"
(e.g., wind- or bird-borne) dispersal of non-native pests or diseases
to remote islands such as Nihoa Island should increase, and more
intensive monitoring will be necessary.
APPROVED PLAN:
Management Practices - 2 (DRAFT) - Management Practices
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
U.S. Fish and Wildlife Service. 1984. Northwestern Hawaiian Islands
Passerines Recovery Plan. U.S. Fish and Wildl. Serv., Portland, OR.
66 pp.
The Nihoa millerbird belongs to a group of Old World warblers
demonstrating an amazing ability to colonize small islands over vast
distances of water. Two millerbirds once inhabited the leeward
Hawaiian Islands. The Laysan millerbird perished when feral rabbits
devoured all living vegetation on Laysan Island - ample evidence that
alien herbivores should never be brought to small oceanic islands.
The isolated island environment of the millerbird has shielded the
birds from mammalian predation and mosquito borne diseases, two
sources of mortality against which Nihoa millerbirds have probably
lost effective defensives. Protecting Nihoa millerbirds from these
serious outside threats is the principal goal of the Northwestern
Hawaiian Islands Passerines Recovery Plan. Proposed recovery actions
include:
- preventing unauthorized access to Nihoa Island (principally
by boat);
- preventing establishment of alien organisms (plant and
animals) and setting up a plan to monitor the island and to
eliminate such organisms should they reach the island;
- preventing the outbreak of avian disease;
- monitoring the species and its habitat, and;
- looking into the feasibility of establishing a second
population on Laysan Island.
Maintaining millerbirds on only one island exposes them to a
greater risk of extinction.
Ongoing recovery actions are: (1) review of the Hawaiian Islands
NWR Master Plan and (2) population surveys.
Management Practices - 3 (DRAFT) - References
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
References
***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****
01 Rothschild, W. 1982. Descriptions of seven new species of birds
from the Sandwich Islands. Ann. Mag. Nat. Hist. Vol. X:109.
02 Wetmore, A. 1924. A warbler from Nihoa. Condor 26:177-178.
03 Munro, G.C. 1960. Birds of Hawaii. Rev. Ed. Charles E. Tuttle
Co., Inc., Rutland, VT. 192 pp.
04 American Ornithologist's Union. 1983. Checklist of North American
birds. 6th Ed. Allen Press, Inc., Lawrence, KS. 877 pp.
05 Vanderbilt, G. and R.M. de Schauensee. 1941. Zoological results
of the Vanderbilt Nihoa expedition. I. Summary of zoological
explorations and the birds of Nihoa. Notulae Naturae, Acad. Nat.
Sci., Phila., No. 86:1-14.
06 Sincock, J.L. and E. Kridler. 1977. The extinct and endangered
endemic birds of the Northwestern Hawaiian Islands. Unpubl. ms.
U.S. Fish and Wildl. Serv., Honolulu, HI. 111 pp.
07 U.S. Fish and Wildlife Service. 1984. Recovery plan for the
Northwestern Hawaiian Islands passerines. U.S. Fish and Wildl.
Serv., Portland, OR. 66 pp.
08 Henshaw, H.W. 1902. Birds of the Hawaiian Islands; being a
complete list of the birds of the Hawaiian possessions, with notes
on their habits. Thos. G. Thrum, Honolulu, HI. 146 pp.
09 Conant, S. 1984. Plumage color changes in a Nihoa millerbird
Acrocephalus familiaris. Condor 86(2):212.
10 Clapp, R.B., E. Kridler and R.R. Fleet. 1977. The natural history
of Nihoa Island, Northwestern Hawaiian Islands. Atoll Res. Bull.,
No. 207. Smithsonian Inst., Wash., D.C. 147 pp.
11 Ely, C.A. and R.B. Clapp. 1973. The natural history of Laysan
Island, Northwestern Hawaiian Islands. Atoll Res. Bull., No. 171.
Smithsonian Inst., Wash., D.C. 361 pp.
12 Banko, W.E. 1979. History of endemic Hawaiian birds specimens in
museum collections. CPSU/UH Avian History Rept. 2. Coop. Nat. Park
Res. Studies Unit, UH Manoa, Dept. of Bot., Honolulu. 80 pp.
13 Rothschild, L.W. 1893-1900. The avifauna of Laysan and the
neighboring islands with a complete history to date of the birds of
the Hawaiian possessions. R.H. Porter, 7 Princes St., London.
320 pp.
14 Marshall, D.B. 1964. Treasure islands - of wildlife. Audubon
Magazine 66:160-165.
15 U.S. Fish and Wildlife Service. 1985. Recovery news: plan
approved for three songbirds of the Northwestern Hawaiian Islands.
Endangered Species Tech. Bull. 10(2):8-10.
16 Munro, G.C. 1941. Birds of Hawaii and adventures in bird study:
an ocean cruise. 'Elepaio 2(6):41-43.
17 Kramer, R.J. 1961. Report on trip to Nihoa Island. Unpubl. Rept.
HI Dept. of Fish and Game, Honolulu. 21 pp.
18 Kramer, R.J. and J.W. Beardsley. 1962. A report on a survey trip
to the Hawaiian Islands National Wildlife Refuge, June 1962. and
Entomological report. Unpubl., HI Dept. of Fish and Game,
Honolulu. 17 pp.
19 Woodside, D.H. and R.J. Kramer. 1961. A report on a survey trip
References - 1 (DRAFT) - References
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
to the Hawaiian Islands National Wildlife Refuge March 1961. Unpub
HI Dept. of Fish and Game, Honolulu. 31 pp.
20 Conant, S. 1983. An analysis and comparison of habitat types on
Nihoa and Necker Islands, HINWR, as they relate to the feasibility
of establishing the Nihoa millerbird on Necker Island. Unpubl.
U.S. Fish and Wildl. Serv., Honolulu, HI. 21 pp.
21 Conant, S. 1983. Ecological requirements of the Nihoa millerbird
and the Nihoa Finch, including an analysis of management options
for the millerbird. Unpubl. U.S. Fish and Wildl. Serv., Honolulu,
HI. 47 pp.
22 U.S. Fish and Wildlife Service. 1984. Report-biological
investigations: Nihoa, Necker, Laysan, Lisianski, Pearl and Hermes
Reef, Midway 19 June-19 July, 1984. Unpubl., U.S. Fish and Wildl.
Serv., Honolulu, HI. 16 pp.
23 Berger, A.J. 1972. Hawaiian birdlife. The Univ. Press of Hawaii,
Honolulu. 270 pp.
24 Conant, S. 1985. Recent observations on the plants of Nihoa
Island, Northwestern Hawaiian Islands. Pac. Sci. 39(2):135-149.
25 Fisher, W.K. 1903. Birds of Laysan and the leeward islands.
Bull. U.S. Fish Comm. for 1903 Vol. 23(3):769-807.
26 Fisher, W.K. 1903. Notes on the birds peculiar to Laysan Island,
Hawaiian group. Auk 20(4):384-397.
27 Fefer, S. 1985. Summary of Hawaiian Islands NWR endangered
species surveys conducted in 1985 for Endangered Species Technical
Bulletin. Unpubl. memo. U.S. Fish and Wildl. Serv., Honolulu, HI.
2 pp.
28 U.S. Fish and Wildlife Service. 1977. Hawaiian and Pacific
Islands National Wildlife Refuge complex narrative report CY 1977.
Unpubl., U.S. Fish and Wildl. Serv., Honolulu, HI. 3 pp.
29 Sincock, J. 1978. 1978 endangered species population data for
leewards. Unpubl. U.S. Fish and Wildl. Serv., Corresp. to Barry
Brady. U.S. Fish and Wildl. Serv., Honolulu, HI.
30 Richardson, F. 1954. Report on the two native passerines of
Nihoa, HI. Condor 56:224.
31 Delacour, J. 1928. Les oiseaux des Iles Hawaii. Revue d'histoire
naturelle. Part II. Oiseaux 9(6):183-190; (7)210-221; (8)242-251.
32 Conant, S., M.S. Collins and C.J. Ralph. 1981. Effects of
observers using different methods upon the total population
estimates of two resident island birds. Studies in Avian Biol.,
No. 6:377-381.
33 Sincock, J.L., E. Kridler and P. Sekora. 1975. Population surveys
of endangered species of the Hawaiian leeward islands. Unpubl.
USFWS Ann. Res. Prog. Rept. Proj. P-H-IV. Patuxent Wildl.
Res. Ctr., Laurel, MD. 4 pp.
34 Sincock, J.L. 1979. A proposal to transplant the Nihoa millerbird
and Nihoa Finch to increase their survival potential. Unpubl.
Rept. USFWS, Patuxent Wildl. Res. Ctr., Laurel, MD. 8 pp.
35 Conant, Sheila. 1986. Pers. comm. Honolulu, HI.
36 Dill, H.R. and W.A. Bryan. 1912. Report of an expedition to
Laysan Island in 1911. U.S. Dept. of Agric. Biol. Surv. Bull. 42.
Gov. Printing Off., Wash., D.C. 30 pp.
37 Bailey, A.M. 1956. Birds of Midway and Laysan Islands. Denver
Mus. of Nat. Hist., Mus. Pict. 12:1-130.
References - 2 (DRAFT) - References
Species MILLERBIRD, NIHOA
Species Id ESIS101043
Date 14 MAR 96
38 Hawaii Audubon Society. 1981. Hawaii's birds. 3rd Ed. Honolulu,
HI. 96822. 96 pp.
39 van Riper, S. and C. van Riper III. 1985. A summary of known
parasites and diseases recorded from the avifauna of the Hawaiian
Islands. In Hawai'i's terrestrial ecosystems preservation and
management. CPSU/UH, Honolulu, HI. 584 pp.
***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****
01 U.S. Fish and Wildlife Service. 1984. Recovery plan for the
Northwestern Hawaiian Islands passerines. U.S. Fish and Wildl.
Serv., Portland, OR. 66 pp.
02 American Ornithologists' Union. 1983. Checklist of North American
birds. 6th ed. Allen Press, Inc., Lawrence, KS. 877 pp.
03 Wetmore, A. 1924. A warbler from Nihoa. Condor 26:177-178.
04 Sincock, J.L. and E. Kridler. 1977. The extinct and endangered
endemic birds of the Northwestern Hawaiian Islands. Unpubl. ms.
U.S. Fish and Wildl. Serv., Honolulu, HI. 111 pp.
05 Clapp, R.B., E. Kridler, and R.R. Fleet. 1977. The natural
history of Nihoa Island, Northwestern Hawaiian Islands. Atoll Res.
Bull., No. 207. Smithsonian Inst., Wash., D.C. 147 pp.
06 Olson, S.L. and H.F. James. 1982. Prodromus of the fossil
avifauna of the Hawaiian Islands. Smithsonian Contrib. to Zoo.
#365. Smithsonian Inst. Press, Wash., D.C. 59 pp.
07 Ely, C.A. and R.C. Clapp. 1973. The natural history of Laysan
Island, Northwestern Hawaiian Islands. Atoll Res. Bull., No. 171.
Smithsonian Inst., Wash., D.C. 361 pp.
References - 3