Laysan Finch

Telespyza cantans

Description

The Laysan finch, Telespyza cantans, is a songbird about 6 in (15.2 cm) long, with a distinctive bluish gray, conical bill. Males have a conspicuous bright yellow head, throat and breast, with dark streaking on the upper back blending to gray on the lower back. Females are brown-streaked overall with a faint wash of greenish yellow, particularly on the breast. The Laysan finch was also known by the scientific name Psittiorostra cantans.

Behavior

The Laysan finch shows little fear of people and is easily caught. Because of its melodious song, it was considered a good cage bird by early explorers. It feeds on both plant and animal matter, including seeds, tender shoots of plants, flowers, and the eggs of other birds.

Laysan finches are known to feed on a wide variety of plant and animal material. They will take seeds, tender shoots of bushes and grasses, flowers, especially those of Tribulus (Nohu) and Eragrostis, and eggs of many species of birds. The incidence of predation on seabird eggs may be related to the presence of humans on the island who cause nesting seabirds to temporarily flush from their nests. They are also known to forage on dead seabirds for the emerging fly larvae or for other invertebrates.

They have been observed drinking water from the saline lagoon and from a spring. Otherwise, water requirements for this species are probably met through moisture obtained from food consumption.

Eggs may be laid as early as February or March, but most egg-laying occurs from late April to early June. Clutch size is normally three eggs, but ranges from two to four. Most nesting now occurs in clumps of bunchgrass, although older reports suggest these birds used other nesting sites such as holes in rocky areas and even buildings (which were formerly present on Laysan Island). However, since Eragrostis has become much more common, they apparently now use only clumps of this bunchgrass as nest sites.

The nest is a shallow cup made of dead grass blades and rootlets. The few nests (seven) that were measured by Richard S. Crossin in 1960 averaged roughly 5.4 in (13.7 cm) across and 2.7 in (6.9 cm) high. They were usually located several inches or centimeters above the ground, centered in a grass clump and well concealed.

Based on limited observations of a few captive birds, incubation takes about 16 days and the nestling period lasts about another 15 days. The peak of nesting appears to be in mid-spring although nesting has been observed as early as February. Most young have fledged by late July or early August. There are no data on number of young successfully fledged per nest.

Habitat

Laysan Island is in the northwestern Hawaiian Islands, a chain extending from Nihoa Island, 250 mi (402.3 km) northwest of Oahu, to Kure Atoll, to more than 1,000 mi (1,609.3 km) to the northwest. Laysan is a small coral island of about 2 sq mi (5.2 sq km), ringed with sand dunes. The maximum elevation is 56 ft (17.1 m). A salt-water lagoon is located in the interior above an ancient volcanic crater.

The Laysan finch requires dense vegetation for nesting and foraging, typically shrubs and matting plants, such as the herb Nama sandwichensis and the shrub Scaevola. It favors bunchgrass (E. variabilis ) for nesting.

Distribution

Apparently this species of finch is adapted to Laysan Island and nearby reefs. Early explorers described the finch as "exceedingly common," and rough population estimates in the early 1900s ranged between 2,700 and 4,000 birds. Rabbits were introduced in 1903 and virtually denuded the island of vegetation, causing a rapid decline in finches. By 1923 estimates suggested that only about 100 finches remained. The Laysan finch was successfully introduced on East Island (Midway) in 1891 but disappeared after rats became established there in 1943.

Today the Laysan finch is found in all the vegetated areas on the island. A separate population, established on Pearl and Hermes Reef, has spread from there to nearby small islands. The total Laysan finch population is about 15,600 birds.

Threats

After rabbits were removed from Laysan in 1923, vegetation reclaimed about half the island, stimulating recovery of the Laysan finch population. Other threats remain, however. The Laysan finch is highly susceptible to avian diseases, which are a constant threat to such a fragile island ecosystem. The Laysan finch population is currently monitored for signs of disease.

Any natural disaster, such as a severe hurricane or a tidal wave, could destroy a large part of the population, and probably has from time to time in the past. The introduction of finch populations to other islands has provided some measure of insurance against extinction from a natural disaster.

Conservation and Recovery

U. S. President Theodore Roosevelt established the Hawaiian Islands Reservation, which included Laysan Island, in 1909. In 1940 the area was made a wildlife refuge and has been designated as a Research Natural Area, under the jurisdiction of the Department of the Interior. Access to the island is prohibited except by special permit.

In 1967, 108 Laysan finches were released on Southeast Island of Pearl and Hermes Reef. This population has apparently established a breeding population on this island at or near carrying capacity and subsequently on neighboring islands of Pearl and Hermes Reef.

Contact

Regional Office of Endangered Species
U.S. Fish and Wildlife Service
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

References

Scott, J. M., et al. 1988. "Conservation of Hawaii's Vanishing Avifauna." Bioscience 38(4):238-253.

U.S. Fish and Wildlife Service. 1984. "Recovery Plan for the Northwestern Hawaiian Islands Passerines." U.S. Fish and Wildlife Service, Portland.