Hawaiian Common Moorhen
Hawaiian Common Moorhen
Gallinula chloropus sandvicensis
|Listed||March 11, 1967|
|Description||A medium-sized, duck-like waterbird, black above and slate-blue below with white dashes along the flank and white markings beneath the tail.|
|Habitat||Freshwater, open wetlands.|
|Food||Aquatic plants and invertebrates.|
|Reproduction||Lays eggs in a nest built of rotting vegetation.|
|Threats||Destruction of habitat through conversion to agricultural and urbanized land-uses, habitat degradation caused by other activities, changes in hydrology, introduction of avian diseases, effects of pesticides and other potentially toxic chemicals, predation of eggs and adults by introduced mammals, especially mongooses.|
The Gallinula chloropus sandvicensis (Hawaiian common moorhen) is a medium-sized waterbird that reach a length of 12-14 in (30-36 cm). Also commonly known as the Hawaiian gallinule, it is black above and slate-blue below with white dashes along the flank and white markings beneath the tail. Legs and feet are yellowish green with a red band (garter) around the upper leg. Both sexes are similar in appearance. This waterbird is a subspecies of the common moorhen of North America and Eurasia. Gallinula chloropus sandvicensis is now nonmigratory, although it presumably originated from stray migrant mainland birds that colonized Hawaii. The Hawaiian name for the Gallinula chloropus sandvicensis is "alae'ula."
The reclusive Gallinula chloropus sandvicensis generally nests in shallow water in areas of dense emergent vegetation. Plant tops are folded over and interwoven to create a platform nest. Although some breeding occurs year round, most nesting activity is from March through August, keyed to water levels and plant growth. Average clutch size is about six eggs but can be as high as 13. Chicks swim away from the nest shortly after hatching, although they still depend upon the parents for several weeks. The moorhen is an opportunistic feeder whose diet can include algae, aquatic insects, mollusks, seeds, and other plant matter.
The Gallinula chloropus sandvicensis nests and feeds in a variety of wetland habitats-freshwater ponds and reservoirs, marshes, taro patches, and beside streams or irrigation ditches-where there is dense vegetation. Salt or brackish water is generally avoided for nesting sites, but may be used for feeding. Most of the Gallinula chloropussandvicensis' habitat occurs below 400 ft (122 m) elevation.
The Gallinula chloropus sandvicensis was historically widespread in the Hawaiian archipelago. It was considered common in the 1800s on all the main Hawaiian Islands except Lanai and Kahoolawe.
The Gallinula chloropus sandvicensis had reached a precarious state by 1947. Populations on Hawaii and Maui had been extirpated, while the Oahu population barely survived; surveys in the 1950s and 1960s estimated there were no more than 60 living Gallinula chloropus sandvicensis. The decline of this species was caused by the destruction of most of its wetland habitat through conversion to agricultural and urbanized land-uses, habitat degradation caused by other activities, changes in hydrology, the introduction of avian diseases, effects of pesticides and other potentially toxic chemicals, and predation of eggs and adults by introduced mammals, especially mongooses. These are all ongoing threats.
Conservation and Recovery
The U.S. Fish and Wildlife Service is preparing a Recovery Plan for the Gallinula chloropus sandvicensis, which in 1999 was released in its Second Revision. The objective of the plan is to increase the abundance of the Gallinula chloropus sandvicensis to at least 1,500 birds. This will largely be done by protecting and enhancing wetland habitat. Captive-breeding and release will also be undertaken. The populations of the endangered Gallinula chloropus sandvicensis will be monitored, and research undertaken into its biology and habitat needs. The Gallinula chloropus sandvicensis has already recovered somewhat in abundance, although it remains endangered. Its population numbered between 200-400 birds in the mid-1990s, most of which were found on Kauai among taro fields on the Hanalei National Wildlife Refuge and in a marsh near the community of Paradise Pacific. Other birds were found on James Campbell National Wildlife Refuge and among the Haleiwa lotus fields on Oahu. A small population was reintroduced to Molokai in 1983.
U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
U.S. Fish and Wildlife Service. 9 July 1999. "Availability of Draft Revised Recovery Plan for Hawaiian Waterbirds, Second Revision." Federal Register 64 (131):37148-37149