ARTICLES ON HAWAIIAN BIRDS AND BIRDWATCHING AND OTHER PACIFIC WILDLIFE

The Hawaiian Moorhen - Distribution and Population Status

The Hawaiian Moorhen is very similar to the mainland form being dark grey to black with a white streak on each side and white on the undertail coverts forming an inverted "v". The legs are green with varying amounts of orange and yellow, depending on sex and age. The bill is red with a yellow-orange tip and the frontal shield is red. The frontal shield appears slightly larger and extends higher up the forehead than on the mainland form. Juvenile birds are browner in plumage and have less colourful and smaller frontal shields.

The Hawaiian Moorhen or Gallinule is a subspecies of the Common Moorhen or Gallinule (Gallinula chloropus) which has a cosmopolitan range throughout the World except Australia, and was first noted by naturalists during Captain Cook's voyage in 1779 (Stresemann 1950). In 1877 Streets published a full description of the Hawaiian Moorhen (Wilson and Evans 1893).

Historical Range and Population Status

The species was described as being common and widespread in 1877 (Streets 1877) and was present on five of the main Hawaiian Islands: Kaua'i, O'ahu, Moloka'i, Maui and Hawai'i. Dole in 1879 was the first naturalist to document the species habitat requirements and its distribution in the islands. He stated that the Moorhen frequented swamps, ponds, streams and taro patches - much the same as today. Henshaw noted in 1903 that the species was on a general decline in Hilo on Hawai'i and observed birds being shot, although he states that these were often thrown away and therefore were presumably not taken for food. Munro (1960) stated that he found the species common on all the "main" islands up to 1891.
By 1947 Schwartz and Schwartz (1949) considered the species status as "precarious".

O'ahu population

The species appears to have continued to be abundant on O'ahu until after the turn of the century, with birds still being regularly observed in Honolulu during the 1920's and nesting records in city parks in the early 1940's. During the 1970's and 1980's surveys showed a sharp decline in numbers and even in the once prolific lotus and taro fields no more than 100 birds could be located on surveys. Numbers elsewhere were very low with counts of only five to eight individuals.
Engilis & Pratt (1993) reported the population as stable on O'ahu during the 1980's but its dependency on aquaculture rendered the species existence as precarious. However, Nagata (1983) reported almost four times as many birds per hectare on lotus farms on O'ahu than were present on unmanaged non-agricultural wetlands. Fish and Wildlife Service data (USFWS 1985) estimated the O'ahu population at 250 individuals during the early 1980's. As on Kaua'i the secretive nature of the species probably conceals the true number present. Between 1977 and 1987 Haleiwa lotus fields accounted for 51.4 percent of the total counted in winter State surveys (Engilis 1988). Photo of Hawaiian Moorhen chick at Hanalei NWR, Kaua'i, summer 1998 © by Christian Melgar.

Moloka'i population

On Moloka'i the species was regarded as common by early naturalists and was still being observed in the 1930's and 1940's and in the 1950's and 1960's birds were regarded as locally common in some areas. After this time though observations rapidly diminished with only five sightings during January waterbird counts by the Hawaii Division of Forestry and Game between 1955 and 1964, the maximum number of individuals involved being nineteen in a single year. Sightings became fewer and fewer and the last individual was reported in 1973. Surveys in the 1970's and early 1980's failed to locate any birds. In 1983 three pairs were transported to the island from O'ahu and released at the Kakahai'a National Wildlife Refuge. No Moorhen have been reported from Moloka'i since 1985.

Maui population

Reports for Maui are very few and the species has not been reported on the island since the turn of the century. An attempted re-establishment in 1959 was unsuccessful and birds have not been noted on any subsequent searches. It is presumed that the Moorhen is extinct on Maui.

Hawai'i population

The story for Hawai'i is similar to that of Maui with early sightings between 1779 and 1887, by 1898 however the species had all but disappeared from the island. Re-establishment attempts during the 1920's and 1930's and later in the 1950's, including some continental birds, all proved unsuccessful and subsequent surveys have failed to locate any birds.

Kaua'i population

Moorhen on Kaua'i were reported as still being numerous and even "especially abundant" in the wetlands near Waimea at the beginning of the century (Banko 1987), from this it can be hypothesized that the species would have been widespread and common due to the large amount of available and suitable habitat that the island possessed. By the 1960's the species was deemed an "uncommon resident". Surveys during the 1970's and 1980's showed a marked decline in numbers with only a few sites holding notable numbers, such as Hanalei (50 - 75 birds) and Paradise Pacifica (10 - 15 birds). Most other sites revealed only ones or twos with occasional larger gatherings. In the mid-late 1990's counts at Hanalei NWR rose markedly and up to 350 were counted on the refuge alone, however by the winter of 1997 the numbers had dropped to a maximum of about 30 - 50 birds, with a few counts into the 70's. The marked decrease coincided with a large increase of Coots on the refuge (from c.120 to over 700) and this may partially explain the severe drop in numbers. Moorhen appear more aggressive to Coots when it is one on one, or just a few Coots, but large gatherings of Coots seem to be "too much" for the Moorhens to cope with. The number of Coots at Hanalei dropped fairly quickly after the peak counts and within two to three years the numbers had returned to normal, the Moorhen population however has not returned to the high numbers recorded previously and it must be questioned whether the increased Coot population was/is wholly responsible.

As the Moorhen is undoubtedly the most secretive of the waterbird species in the Hawaiian islands it is likely that many are overlooked and the fact that it often inhabits small, well vegetated wet areas means that the species can go undetected for long periods, however the massive reduction in numbers whilst observer awareness has increased no doubt shows that the species has genuinely undergone a substantial decline in its population since the beginning of the 20th Century. Engilis & Pratt (1993) gave an estimate of 500 individuals for Kaua'i based on a USFWS report and this number certainly appears feasible with the amount of suitable habitat.

Only a few specific Hawaiian Moorhen papers have been published. Three useful ones are a paper on the nesting ecology of the Hawaiian Common Gallinule by Byrd and Zeillemaker (1981), the second is by Byrd et al. (1985) on breeding behaviour and the other is an MSc thesis on the status of the Hawaiian Gallinule on Lotus farms and a marsh on Oahu, Hawaii by Nagata (1983). Little information on feeding habitat requirements has ever been produced.

The Hawaiian Moorhen was listed on March 11th 1967 (32 Federal register 4001).

Occurrence of Moorhen on Hawaiian Islands.

NI'IHAU	KAUA'I	O'AHU	MOLOKA'I	LANA'I	MAUI	HAWAI'I
NO	YES	YES	FORMERLY	NO	FORMERLY	FORMERLY

Moorhen nest with eggs at Hanalei NWR, Kaua'i. Summer 1998.

References

BANKO, W.E. 1987. Historical synthesis of recent endemic Hawaiian birds. Part I. Population histories - species accounts, freshwater birds: Hawaiian Gallinule, 'Alae -'ula. Cooperative National Park Resources studies unit, University of Hawaii at Manoa, CPSU/UH Avian History report No. 12.

BYRD, V.G., R.H. COLEMAN, R.J. SHALLENBERGER and C.S. ARUME. 1985. Notes on the breeding biology of the Hawaiian race of the American Coot. The Elepaio 45. pp 57 - 63.

BYRD, G.V. and C.F. ZEILLEMAKER. 1981. Nesting ecology of the (Hawaiian) Common Gallinule. Undated report. Fish and Wildlife Service, Honolulu

ENGILIS Jr., A. 1988. Surveys and inventories of waterbirds in the state of Hawaii, a ten year trend analysis. Unpublished. Pitt. Rob. Report W-18-R-12,R-III-A

ENGILIS, Jr, Andrew and T.K. PRATT. 1993. Status and population trends of Hawaii's native Waterbirds,1977-1987. Wilson Bulletin, vol. 105 (1) pp 142-158.

HAWAIIAN WATERBIRD RECOVERY TEAM. 1977. Hawaiian Waterbird Recovery Plan. U.S. Fish and Wildlife Service. Washington,D.C.

MUNRO, G.C. 1960. Birds of Hawaii. Vermont and Tokyo: Charles E. Tuttle Co

NAGATA, S.E. 1983. Status of the Hawaiian Gallinule on lotus farms and a marsh on Oahu, Hawaii. M.Sc. Thesis, Colorado State University, Fort Collins, Colorado.

SCHWARTZ, C.W.and SCHWARTZ, E.R. 1949. The game birds in Hawaii. Board of Agriculture and forestry, Honolulu

STREETS, T.H. 1877. Description of a new moorhen from the Hawaiian Islands. Ibis 25-27

U.S. FISH AND WILDLIFE SERVICE. 1985. Recovery plan for the Hawaiian Waterbirds. U.S Fish and Wildlife Service, Portland, Oregon. 99pp

WILSON, S.B. and A.H. EVANS. 1893. Aves Hawaiienses: Birds of the Sandwich Islands. Arno Press (1974), New York, NY. 257pp

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

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