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ARTICLES ON HAWAIIAN BIRDS AND BIRDWATCHING AND OTHER PACIFIC WILDLIFE

Endemic birds of the Northwestern Hawaiian Islands

Three passerine species are presently endemic to the Northwest Hawaiian Islands - Laysan Finch, Nihoa Finch and Nihoa Millerbird. Three other endemic species have historically been found on these islands but are now extinct - Laysan Millerbird, Laysan Honeycreeper and Laysan Rail. The Laysan Duck is also presently confined to Laysan Island in the Northwest chain, but was once found throughout the Main Hawaiian Islands and has already been covered in a previous account on the Birding Hawaii Website.

The Northwest Hawaiian Islands

These islands stretch from Nihoa in the east to Kure Atoll in the west. Nihoa lies about 170 miles west of Kaua'i and Kure Atoll lies about 1400 miles west of Kaua'i. In order from east to west the islands are: Nihoa, Necker, French Frigate Shoals, Gardner Pinnacles, Laysan, Lisianski, Pearl and Hermes Reef, Midway and Kure Atoll. All the islands are home to numerous seabirds including Laysan and Black-footed Albatross, Great Frigatebird, Masked Booby, Red-footed Booby and Brown Booby, Sooty Tern, Gray-backed tern, White Tern, Wedge-tailed Shearwater, Christmas Shearwater, Bulwer's Petrel, Sooty Storm Petrel, Bonin Petrel and Red-tailed Tropicbird, amongst others. Monk Seals pup in the clear waters around the islands and can be found lazing on the sandy beaches of some of the low-lying islands. Pacific Green Turtles nest on these same low-lying beaches in large numbers. The three species of extant passerines endemic to these remote islands are of great interest and value to birders and ornithological researchers, as they all exhibit interesting and in some cases unusual behaviour. Unfortunately the two islands on which the species concerned inhabit are strictly off-limits to most people and so most will never be able to observe the species in their natural habitat.

Laysan Finch (Telespiza cantans)

This species is a fairly abundant endemic of Laysan Island, where it occurs in all habitats throughout the island. The species is a conspicuous part of the island's avifauna and was reported by most early visitors to the island, although some named the species Laysan Canary. The bright colours of the adults, their song and their hardiness made it a popular cagebird and many ships visiting Laysan frequently transported birds to Midway, Honolulu and perhaps elsewhere. The species was formally named from a captive bird purchased in Honolulu from a shipment of 60 imported in 1889.

Ely & Clapp (1973) state: " A common term used by various observers through 1915 in describing the finch population, 'everywhere in abundance', is understandable. The finches were tame, constantly in evidence and entered occupied buildings where they explored everything in sight, roosted, sang and (in 1923) even built nests. Few observers, however, attempted the difficult task of estimating the finch population. Dill and Bryan estimated 2,700 birds in 1911 and Munter estimated 4,000 in 1915. Finches were still 'very common' in 1916. The population dropped to 100 birds in 1923 but had increased to at least 1,000 in 1936. This drastic fluctuation in numbers seems to have paralleled the degradation and subsequent recovery of the vegetation. Birds were again considered 'quite abundant' in 1950 by Brock who estimated about 5,000 birds in 1957. Warner estimated a conservative 10,000 birds as the result of a transect census in 1959. Numbers are believed to have remained at about this level to the present time".

The population during the 1990's and early 21st century was considered to be about 10,000 birds (twenty year average), with approximately 500 - 800 of these scattered on several small islands at Pearl and Hermes Reef, where they have been introduced. Populations have varied however between 5,000 and 20,000 over this period. Although extremely vulnerable to disease (none known on the islands at present), potential introductions of non-native plants and animals, fluctuations in food availability, catastrophic events, such as hurricanes and tsunamis, weather conditions and their lack of fear of humans, the population appears to be adaptable and able to recover from even quite severe population loss and so the species should be relatively safe in the future.

Fisher noted in 1902 that the species was "quite fearless and unsuspicious. It is also saucy to a marked degree, and ignores the presence of man when he is peaceably disposed. They do not fly far, but prefer to alight soon, and run along the ground, or elude pursuit by suddenly crouching under a grass tussock." Schauinsland (1899) stated that at meal time finches would "sit on the edge of our plates and share our rice and bacon". Finches exhibit much the same behaviour today.

The Finches diet consists of the soft parts of grass stems, tender shoots of bushes, seeds, and eggs. Apparently the major staple of their diet are the seeds of Tribulus and Eragrostis plants, with many observers noting these species being eaten more than any other species. Their keen passion for birds' eggs is well-known and has been described by many researchers. Any eggs left unattended for a few moments are liable to be broken into and their contents eaten. The finches also concentrate at the edge of tern colonies and take advantage of any disturbances by flying in and attacking the eggs whilst the adult birds are in flight. The finches are not fussy about which eggs they eat and many species have lost eggs to them including Bulwer's Petrel, Wedge-tailed Shearwater, Sooty, Gray-backed and White Terns and Black and Brown Noddies, although presumably any species is at risk. Bryan and Dill (1912) also reported that finches would even eat the eggs of other finches, but this has not been reported subsequently. Albatross eggs may be too hard for the finches to be able to break and so eggs being eaten by finches are quite likely to have been broken by other species, such as Bristle-thighed Curlew or Monk Seals, or have become rotten and started to decompose and burst under internal pressure.

Crossin (1966) noted that the egg-eating trait appears to be a learned skill, with juvenile birds continuing to eat only seeds and plants until shown by adults how to attack and eat eggs. He also noted that the combination of human presence and finch attacks resulted in high Sooty Tern egg loss. Stadel (1967) estimated that at least 10% of eggs were lost during June 1967. The species, as an opportunistic feeder, has also been reported feeding on maggots and dead birds and dead Albatross chicks. The habit of eating birds eggs was probably greatened during the years when vegetation had been almost completely wiped out by overgrazing by introduced rabbits, although the species obviously ate eggs to some degree before this as egg eating was reported in at least 1903.

The species nests mainly from May through to July and the cup-shaped nest is compiled of grass and plant stems placed in a grass tussock or bush. In the past birds have been reported nesting in February and March but no recent reports of nesting have fallen outside the summer period. Crossin (1967) described the nest as follows: In the few nests found which were just begun, long grass rootlets formed the basis for the bottom and side walls. In all finished nests dead grass blades and stems (were) interwoven among rootlets and the entire structure...(was) composed of these plant portions. there was essentially no cup lining, the entire cup portion being constructed of smaller and finer grass blades and rootlest. The finished structure is...compact and the surrounding grass blades allow the nest to remain in place for long periods.

Laysan Finches were successfully introduced to Midway in 1891 and following years and survived until 1944 after the accidental introduction of rats. Laysan Finches no longer occur on Midway. In 1967 birds were introduced to Southeast Island, Pearl and Hermes Reef and are now well established there. Laysan Finches breed successfully in captivity and the survival of the species was considered "assured" by Ely and Clapp (1973). Several importations to Honolulu were unsuccessful, perhaps due to insect-borne bird disease. Collar et al. (1994) class the species as Vulnerable, due to the species habitat being of limited size (<100km squared).

Nihoa Finch (Telespiza ultima)

This species is confined to the island of Nihoa in the northwest Hawaiian Islands, where it is one of two endemic passerines. The species was named Nihoa Telespiza by Munro (1960) and Bryan who first described the species gave it the scientific name ultima, as he was sure it was the last endemic Hawaiian bird to be discovered. Of course the Nihoa Millerbird and Po'o-uli have both been discovered since then. When Palner visited the island a few years before they missed the Millerbird as they were unable to land. Judge Sanford B. Dole spoke of a picnic party landing on the island in the 1880's and of seeing this species then.

The Nihoa Finch is very similar to the Laysan Finch but smaller. The male has a bright yellow head, neck, and breast with a broad grey band between the neck and mid-back. The lower back and rump of the male are gray. Females have a yellow throat and breast streaked with brown, the head and back are brown streaked with black. It measures about 6 inches in length. Males are showy when singing, holding their wings horizontally away from their bodies and sometimes swaying back and forth. The distress call is a loud, harsh chip and its song consists of loud melodious trills, whistles and warbles.

The species prefers open but vegetated habitat throughout the island. Nihoa Finches build their nests in small holes in rock outcrops 100 to 800 feet above sea level. Egg laying begins in February and may extend to early July, with an average clutch of three eggs. This bird feeds on seabird eggs, insects, seeds, and flower buds. During the nesting season birds nest in holes in cliff outcroppings.

Nihoa was once inhabited by early Polynesians, but few people since then have even dared to take on the rough seas and sheer cliffs of the remote island. Historical records on the Nihoa Finch are very scant, but in 1985, their population was estimated to be 3,200 birds. Population estimates from the last 30 years range between 900 and 6,600 birds. Collar et al. (1994) state that the species numbered 1,080 - 2,340 in 1992 and 1,350-3,810 in 1993, and they list the bird as "Vulnerable", due to a limited distribution. Other recent population estimates have put the population at between 1,000 and 3,000 individuals (Ellis et al., 1992). An attempted introduction of birds to French Frigate Shoals in 1967 was not successful.

The main threats to this species are natural catastrophes such as hurricanes and fire, as well introduction of disease, exotic plants and animals and resulting habitat modification. Typical of small island ecosystems, it is very vulnerable to introduced species and human disturbance, therefore access to the island is authorized only with a permit by the Refuge Manager. Permits are usually issued for management-related research purposes only. Its future survival depends on control of introduced plants and animals and maintenance of the native vegetation on the island. The Nihoa Finch was listed as an endangered species by the U.S. Fish and Wildlife Service on March 11, 1967. Nihoa is part of the Hawaiian Islands National Wildlife Refuge which provides protected habitat for the Nihoa Finch.

Nihoa Millerbird (Acrocephalus familiaris kingi)

This species, endemic to Nihoa, was first discovered in 1923 when a Bishop Museum expedition landed on the island. Dr. Wetmore discovered the bird and described it, naming it for Lieutenant Commander Samuel Wilder King, who commanded the expedition on the minesweeper "Tanager".

The species is generally a rather drab grey-brown colour above and buffy off-white below with a bold supercilium, long tail and thin dark bill. The legs are grey in colour. Both sexes are similar and the males song consists of a metallic bubbling sound, which he gives from an exposed branch..

The Nihoa Millerbird is one of two endemic "Old World" passerines that lived in the Hawaiian Islands, the other being the very similar Laysan Millerbird (Acrocephalus familiaris), which became extinct when rabbits consumed almost all the vegetation on the island between 1912 and 1923. The species feeds almost exclusively on Miller moths, hence the English name. The birds search for insects and moths in dense brush and plants such as goosefoot (Chenopodium sanwicheum) and ilima (Sida Fallax)and are very secretive and elusive. Like the Laysan Finch the species constructs its nest from grass stems and rootlets, which it places low down in small shrubs.

Collar et al. (1994) state that the species population fluctuates between 100 and 700 individuals and class the species as "Vulnerable" for two reasons, firstly the low population size (<1,000 individuals) and secondly for the limited available habitat (64 hectares). Recent population estimates have put the population at between 200 and 400 individuals, with fluctuations bringing the population to a maximum of 600 birds (Ellis et al., 1992).

The Nihoa Millerbird was listed as an endangered species in 1967 under the Federal Endangered Species Act. Nihoa is part of the Hawaiian Islands National Wildlife Refuge created in 1909, and access is restricted due to the island’s fragile ecosystem. It is also designated as a Research Natural Area where state and federal biologists work closely together to monitor and maintain Nihoa’s wildlife and environment. Biologists are considering the possible translocation of sufficient Millerbirds to create a second population on other Hawaiian islands such as Laysan, Kaho`olawe, or Eastern Island at Midway Atoll to reduce the possibility of extinction.

References:

Laysan Finch

BROCK, V. E. 1951. Laysan Island bird census. The Elepaio 12: 16-18.

BRYAN, W. A. and H. R. DILL. 1912. Report of an expedition to Laysan Island in 1911. U.S. Dept. of Agriculture. Biol. Surv. Bull. 42:30pp.

COLLAR, N. J., M. J. CROSBY and A. J. STATTERSFIELD.1994. Birds to Watch 2. The World list of threatened birds. Birdlife International. Cambridge, U.K.

CROSSIN, R.S. and L.N. HUBER. 1970. Sooty Terns egg predation by Ruddy Turnstones. Condor 72: 372-373.

DILL, H. R. and W. A. BRYAN. 1911. Report of an expedition to Laysan Island in 1911. U.S. Dept. of Agriculture. Biol. Surv. Bull. 42:30pp.

ELLIS, S., C. KUEHLER, R. LACY, K. HUGHES, and U.S. SEAL. 1992. Hawai'ian Forest Birds Conservation Assessment and Management Plan. Captive Breeding Specialist Group; IUCN - The World Conservation Union/ Species Survival Commission.

ELY, C. A. and R.B. CLAPP. 1973. The Natural History of Laysan Island, Northwest Hawaiian Islands. Smithsonian Institution and Bureau of Sport Fisheris and Wildlife. u.S. Dept. of the Interior. Washington, D.C., U.S.A.

FISHER, W. K. 1903. Birds of Laysan and the leeward islands, Hawaiian Group. U.S. Fish. Comm. Bull. 23 (part 3): 767-807.

HAWAII AUDUBON SOCIETY. 1997. Hawaii's Birds. Hawaii Audubon Society, Honolulu, Hawai'i.

MUNRO, G. C. 1960. Birds of Hawaii. Charles E. Tuttle Co., Inc. Rutland, Vermont.

MUNTER, W. H. 1915. Report of destruction of bird life on Laysan Island. Ann. Report. Caost Guard for 1915: pp.130-140.

RAUZON, M.J. 2001. Isles of Refuge - Wildlife and History of the Northwestern Hawaiian Islands. University of Hawai'i Press, Honolulu.

SCHAUINSLAND, H. 1899. Drei Monate auf einer Korallen-Inseln (Laysan). Bremen, Nossler. 104pp.

UNITED STATES FISH AND WILDLIFE SERVICE. 2001. Information pages from Dept. of the Interior website on Endemic Hawaiian Birds. USFWS, Pacific Region.

WARNER, R. E. 1959. Wildlife of Laysan Island. The Elepaio 19 : 8-10, 20-23.

NIHOA FINCH

COLLAR, N. J., M. J. CROSBY and A. J. STATTERSFIELD.1994. Birds to Watch 2. The World list of threatened birds. Birdlife International. Cambridge, U.K.

FISHER, W. K. 1903. Birds of Laysan and the Leeward Islands, Hawaiian Group. U.S. Fish. Comm. Bull. 23 (part 3): 767-807.

HAWAII AUDUBON SOCIETY. 1997. Hawaii's Birds. Hawaii Audubon Society, Honolulu, Hawai'i.

MUNRO, G. C. 1960. Birds of Hawaii. Charles E. Tuttle Co., Inc. Rutland, Vermont.

RAUZON, M.J. 2001. Isles of Refuge - Wildlife and History of the Northwestern Hawaiian Islands. University of Hawai'i Press, Honolulu.

UNITED STATES FISH AND WILDLIFE SERVICE. 2001. Information pages from Dept. of the Interior website on Endemic Hawaiian Birds. USFWS, Pacific Region.

NIHOA MILLERBIRD

COLLAR, N. J., M. J. CROSBY and A. J. STATTERSFIELD.1994. Birds to Watch 2. The World list of threatened birds. Birdlife International. Cambridge, U.K.

FISHER, W. K. 1903. Birds of Laysan and the Leeward Islands, Hawaiian Group. U.S. Fish. Comm. Bull. 23 (part 3): 767-807.

HAWAII AUDUBON SOCIETY. 1997. Hawaii's Birds. Hawaii Audubon Society, Honolulu, Hawai'i.

MUNRO, G. C. 1960. Birds of Hawaii. Charles E. Tuttle Co., Inc. Rutland, Vermont.

RAUZON, M.J. 2001. Isles of Refuge - Wildlife and History of the Northwestern Hawaiian Islands. University of Hawai'i Press, Honolulu.

UNITED STATES FISH AND WILDLIFE SERVICE. 2001. Information pages from Dept. of the Interior website on Endemic Hawaiian Birds. USFWS, Pacific Region.

Christian Melgar. Worthing, West Sussex, UK. 2002.

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