ARTICLES ON HAWAIIAN BIRDS AND BIRDWATCHING AND OTHER PACIFIC WILDLIFE

The Hawaiian Coot - Distribution and Population Status

The Hawaiian Coot is a close relative of the American Coot (Fulica americana americana) and was first described in 1848 by Peale (Banko 1987). The taxonomic status of the Hawaiian Coot has been subject to much debate in the past and was only recognised as a distinct species in 1993 (American Ornithologists Union 1993).

Historical Range and Population Status

The Hawaiian Coot occurs on Kaua'i, O'ahu, Moloka'i, Maui, Hawai'i and when seasonal rainfall occurs in sufficient amounts on Ni'ihau. It was described as being common and a widely distributed species before 1900 and could be found in taro patches, ponds, marshes, brackish lakes, reservoirs and streams (Wilson and Evens 1899). Although large flocks were often observed at this time in some areas, a decline in numbers was also noted at some sites and by 1947 the species future was described as "problematical".

The species is widely distributed, being present from sea level to 500 feet elevation in more or less any area where there is suitable water (Schwartz and Schwartz 1952). Numbers recorded from season to season and from year to year have been extremely variable and thus compound the difficulty of accurately assessing the true numbers, despite the relative ease of observation of the species. The high variability in numbers has been commented on by many authors including Griffin et al. (1989), Pratt (1978), Shallenberger (1977) and Udvardy (1960). Several theories have been suggested and some seem feasible. Numbers moving between islands during unusual rainfall to take advantage of newly available wetland areas seems the most plausible, but pre- and post-breeding movements also seem likely.

The suggestion that there is immigration of Coots from mainland America seems to have no data to back it up, in fact, it may be that mainland Coots have never been to or have only extremely rarely, occurred in Hawaii in modern times. The variation in bill form of young Hawaiian Coots has only made substantiation of American Coot records in Hawai'i even more problematical. Engilis & Pratt (1993) noted that often an increase in the official State count was observed throughout the islands and therefore there may be other factors which affect the variability in numbers. For example, it is not known if their data included birds on Ni'ihau, which would disperse after nesting; or whether ephemeral wetlands throughout the chain were adequately surveyed, both during times of drought or heavy rainfall. The effects of these could both at least partially contribute to the pattern being noted in Hawai'i.

Engilis & Pratt (1993) state that American Coots congregate in winter and disperse in summer and that Hawaiian Coots do the opposite, dispersing in late winter and congregating in summer for the non-breeding period, however, they then state that the Hawaiian Coot normally breeds from March through September.
This would presumably mean that birds in the summer period were considered as non-breeders as this was still well within the main breeding season period. Figures for Hanalei NWR do not support their statement, as birds at this site tend to congregate during the winter months, as do their mainland counterparts.
Statewide numbers were estimated at between 2000 and 4000 birds; Kaua'i, O'ahu and Maui supporting 80% of the total.

O'ahu Population

On O'ahu numbers were previously high and remained so into the 1940's, Schwartz and Schwartz counted 500 and estimated a further 500 on Kaelepulu Pond on April 6th 1947, however this site was destroyed in the late 1950's and early 1960's and is no doubt reflected in a fall of a staggering 83% in the average numbers of Coots between two sets of survey data taken in the periods 1956-1961 and 1962-1967. The decline continued through to 1974, with an average of just 76 birds but recovered between 1975 and 1981 with averages of 158 individuals. (Banko 1987).

Moloka'i Population

On Moloka'i up to 250 were observed at a single site during 1946 (Schwartz and Schwartz 1952) and smaller numbers were seen elsewhere in suitable coastal habitat. Numbers during the 1950's through to 1980 appeared stable with average January counts ranging from 32 to 48 individuals most years with one year (1972) when only 9 were recorded. Some individuals may move to here from Maui during heavy rainfall periods (Engilis and Pratt 1993).

Maui Population

Schwartz & Schwartz (1953) reported only seeing one sizeable flock on Maui at Kanaha Pond during their 1946 survey, when they observed 300 birds, elsewhere they only appear to have recorded small numbers. Banko (1987) reports that there was a significant decline in Coot numbers on the island between 1956 and 1981. During the 1990's however the population on Maui, Moloka'i and Lana'i supported the largest Coot population outside of Oahu, with the majority of these occurring on Maui, and mainly at just two sites.

Hawaii population

On the Big Island of Hawai'i the Coot was deemed uncommon and very local during the 1946 survey by the Schwartz's and data collected during the 1950's, '60's and '70's appears to confirm that although the population appears stable the number of individuals is rather low with average high counts of between 37 and 84 individuals, with a slight increase in numbers during the 1973 to 1980 period. (Banko 1987). The present population is estimated to be about 200 birds on the Kona coast and 75 birds on the Hilo coast (Ducks Unlimited survey data 1995 to 1996).

Kaua'i Population

Schwartz and Schwartz during their 1946 survey found birds in most of the lowland wetland areas and commented that the species was scattered but abundant. The peak number they observed was fifty birds at the Grove Farm reservoir in October, perhaps reflecting a post-breeding congregation.
Banko (1987) reported that the year - round usage of wetland habitats on Kaua'i had increased since 1956. When site usage was calculated by Banko in 1987, of 85 habitats in which the species was observed one or more times 55% showed a decreased usage, 33% showed an increase in usage and 12% showed no change in usage when averages were compared between first and last half of the surveys conducted. It appears that Coots on Kaua'i are choosing sites where there are already sizeable numbers of birds, presumably Hawaiian Coots, like their American and Eurasian relatives, are comfortable with being part of a large gathering of birds.

Not surprisingly information for the Hawaiian Coot is rather limited with most literature concentrating on distribution and breeding biology. Notes on the breeding biology of the Hawaiian race of the American Coot by Byrd,Coleman, Shallenberger and Arume (1985) is the most recent investigation of note. An unpublished report by Seymour and Keenan (1997) provides a basic account of feeding activity in managed and unmanaged wetlands at Hanalei NWR on Kauai during the autumn of 1997, but is the only qualitative data that had been collected.

Coot studies elsewhere have been numerous and a large body of work exists for both American, Eurasian and Australian Coots including Alley (1950), Boyd (1948), Burton (1959), Fredrickson (1970), Harris (1957), Kear (1966), Kornowski (1957), Walker (1932) and Weller (1971). Ryan and Dinsmore (1980) investigated time - activity budgets of breeding Coots in Iowa. They stated that foraging and courtship decreased with age whilst time spent defending territory and feeding young increased with age, this being as a result of older birds inhabiting higher quality habitats. The year prior to this they investigated the role of each sex in the nesting and breeding process and found that females spent more time than males feeding their young during the breeding season, males spent slightly more time in defensive behaviour and that both sexes reduced loafing time whilst caring for a brood (Ryan and Dinsmore 1979).

Jones (1940) researched the food habits of the American Coot and provided a species by species account of food types eaten by the species. Perrow et al. (1997) reported on the interactions between the Eurasian Coot and submerged macrophytes and if the species had a negative role in the restoration process. They carried out experiments to record the amount of macrophyte matter being consumed, but ultimately found that it was unlikely that Coots affected the growth and abundance of macrophyte material.

Brinkhof and Cave (1997) investigated the role of food supply on breeding success by date, success independent of date, and what affects success seasonally, and found that seasonal variation in offspring production was a result of seasonal variation in food availability. Cave et al. (1989) also studied territory, in relation to a Coots neighbours age and found that old pairs have larger territories and that the composition of a territory (vegetation, area, shoreline amount) depended on the males age rather than the females. They also found that older males have more territories than young birds; they calculated two ratios that they considered important in territory selection and defence: the age of the male Coot to the mean age of its neighbours and the Coots age to the sum of the ages of its neighbours.

The Hawaiian Coot was listed on October 13th 1970 (35 Federal Register 1607)

Occurrence of Hawaiian Coot in the Hawaiian Islands.

NI'IHAU	KAUA'I	O'AHU	MOLOKA'I	LANA'I	MAUI	HAWAI'I
YES *	YES	YES	YES	YES	YES	YES

* Species present usually only during times of adequate rainfall on this island.

Adult Hawaiian Coot with partial albinism on head, Kaua'i Lagoons Kaua'i, December 1999.

References

ALLEY, R. And H. Boyd. 1947. The hatching and fledging success of some Coot. British Birds 40(1). pp199 - 203.

AMERICAN ORNITHOLOGISTS' UNION 1993.Thirty-ninth supplement of the American Ornithologists' Union Checklist of North American Birds. Auk 110:675-682.

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

BOYD, H.J. and R. ALLEY. 1948. Function of the head coloration of the nesting Coot (Fulica atra) and other Rallidae. Ibis 90: 582-593.

BRINKHOF, M.W.G. and A.J. CAVE. 1997. Food supply and seasonal variation in breeding success: an experiment in the European Coot. Proceedings of Royal Society, London B. pp291-296

BURTON, J.H. 1959. Some population mechanics of the American Coot. Journal of Wildlife Management 23(2). pp203 - 210.

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.

CAVE,A.J.; J.VISSER; A.C. PERDECK. 1989. Size and quality of the Coot (Fulica atra) territory in relation to age of its tenants and neighbours. Ardea 77. pp 87 - 97.

DUCKS UNLIMITED. 1993 to 1997. Survey data for Hawaiian waterbirds. Unpublished data on file at Ducks Unlimited, Sacremento, California.

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

FREDRICKSON, L.H. 1970. Breeding biology of American Coots during severe spring weather. The Wilson Bulletin 81 (4). pp 450 - 453.

GRIFFIN, C.R.,; R.J.SHALLENBERGER; and S.I. FEFER. 1989. Hawaii's endangered waterbirds: a resource management challenge. pp1165 - 1175 in Freshwater wetlands and wildlife. DOE symposium series No. 61. USDOE, Oakridge, Tennessee.

HARRIS, S.W. and W. MARSHALL. 1957. Some effects of severe windstorms on Coot nests. Journal of Wildlife management 21: 471-473

JONES, J.C. 1940. Food habitats of the Amercican Coot with notes on distribution. U.S.Department of the Interior. Wildlife resource Bulletin No.2 .

KEAR, J. 1966. The pecking response of young Coots (Fulica atra) and Moorhens (Gallinula chloropus). Ibis 108:118-122

KORNOWSKI, G. 1957. Contributions to the ecology of the European Coot, Fulica atra. Journal of Further Ornithology 98 (3)pp319 - 353.

PERROW, M.R.; J.H. SCHUTTON; J.R.HOWES; T.HOLZER; F.J. MADGEWICK and A.J.D.JOWITT.1997. Interactions between Coot (Fulica atra) and submerged macrophytes: the role of the birds in the restoration process. Hydrobiologia 342/343. pp241 - 255.

PRATT, H.D. 1978. Do mainland Coots occur in Hawaii? Elepaio 38:73

RYAN, M.R. and J.J. DINSMORE . 1979. Aquantative study of the behavior of breeding American Coots. The Auk 96. pp 704 - 713.

RYAN, M.R. and J.J. DINSMORE. 1980. The behaviorial ecology of breeding American Coots in relation to age. The Condor 82 pp320 - 327.

SCHWARTZ, C.W. and SCHWARTZ, E.R.1952. The Hawaiian Coot. The Auk, volume 69. 1952.

SCHWARTZ, C.W. and SCHWARTZ, E.R.1953. Notes on the Hawaiian Duck. The Wilson Bulletin.Volume 65, No. 1.

SEYMOUR and E. KEENAN.1997. Unpublished report on feeding behaviour of Hawaiian Coots at Hanalei NWR, Kaua'i.

SHALLENBERGER, R.J. 1977. An ornithological survey of Hawaiian Wetlands. Volume I and II. Contract DACW 84-77-C-0036. U.S. Army engineer district, Honolulu

UDVARDY, M.D.F. 1960. Movements and concentrations of the Hawaiian Coot on the island of Oahu. Elepaio 21:20-22

WALKER, 1932. Spirit of the tules, the Coot. Birdlore 34: 322-324

WELLER, M.W. 1971. Experimental parasitism of American Coot nests. The Auk, Volume 88.pp 108 - 115

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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