Millerbird

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Image:Millerbirds.JPG

Hawaiian Name: Nihoa Millerbird
Common Name: Nihoa Millerbird
Scientific Name: Acrocephalus familiaris

Size: 5.1 inches (13 cm)

Habitat: Oceania; Polynesia. It is endemic to the steep, rocky island of Nihoa in the North-western Hawaiian Islands (USA). It previously occurred on Laysan also, where the nominate race was estimated to number 1,500 birds in 1915, but became extinct between 1916 and 1923.

It prefers dense cover near the ground, particularly around the shrubs such as Chenopodium oahuense, Sida fallax and Solanum nelsoni.

Status: Critically Endangered. Global Population: 250-999 Mature individuals with fluctuating trends. Its extinction on Laysan was ultimately caused by the introduction of rabbits, which denuded the island of vegetation (causing severe insect food shortage). On Nihoa, the population size is probably regulated primarily by precipitation levels, which affect the abundance of invertebrate prey (extended droughts for example, are likely to have a negative impact). Severe weather events such as hurricanes may cause direct mortality of millerbirds; a single severe storm could extinguish the population. Fire is a past and potential threat and introduction of detrimental non-native species is a permanent possibility.

Diet: Small beetles, spiders, roaches and larvae. The extinct Laysan population was thought to have fed primarily on moths.

Breeding: Pairs show year-to-year fidelity in specific territories, with nesting apparently correlated with precipitation and most breeding taking place in the winter months (peaking January-March), although the breeding period may be extended in years of high summer rainfall. Nests are located in dense shrubs (mainly C. oahuense) and two eggs are generally laid.

Cool Facts: Nihoa is part of the Hawaiian Islands National Wildlife Refuge and Papahanaumokuakea Marine National Monument. Legal access is controlled by a permit system that is restricted largely to biologists, other researchers, and native Hawaiian cultural practitioners. Strict protocols are followed to ensure that legal permittees do not accidentally introduce new species via seeds, eggs or insects travelling on clothes and equipment. Visiting scientists make efforts to control alien plants by hand weeding.

The Nihoa Millerbird and Laysan Millerbird are the only known Old World warblers (subfamily Sylviinae) that colonized the Hawaiian Archipelago, the most remote group of islands in the world. The Laysan form, discovered first, was named “millerbird” (Henshaw 1902) because of its fondness for feeding on large miller moths (Family Noctuidae: probably Agrotis spp.). The Laysan and the Nihoa millerbirds are generally regarded as (at least) separate subspecies.


Found in Songbird ReMix Threatened, Endangered, Extinct 3 and Songbird ReMix Hawai'i

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