Taiwan Bush Warbler

Locustella alishanensis

台湾短翅蝗莺

IUCN: Least Concern Found in China

Introduction

Old World warbler in the family Locustellidae, endemic to Taiwan. Inhabits undergrowth and grassland at elevations of 1,200–3,000 m (3,900–9,800 ft). First recorded in 1917 and described as a distinct species in 2000 based on distinctive song and morphological differences. The species was formerly considered conspecific with Bradypterus luteoventris and later placed in subspecies idoneus of B. seebohmi before being recognized as separate. Shares taxonomic proximity with the russet bush warbler complex. Assessed as Least Concern by the IUCN.

Description

Small warbler, approximately 14 cm (5.5 in) in length with a body mass of about 10 g (0.35 oz). Sexes are similar in appearance. Head shows dull rufous-brown coloration with narrow dark tips on the crown. Pale buff supercilium and eye-ring are present but not prominent. Upperparts from mantle through wings and tail are uniformly dull russet-brown. Chin and throat are white, with spotting typically present on the lower throat. Upper breast is greyish brown, transitioning to white on the lower breast and belly. Undertail coverts are dark rufous-brown with warm-colored tips. Beak is black, with the lower mandible occasionally pale in winter. Feet are pale pink and eyes are reddish brown. Juveniles display a brownish breast without the spotting seen in adults.

Identification

Field identification relies heavily on vocalizations. Song consists of a repeated sequence of one monotone whistle followed by three or four clicks, typically repeated more than ten times and ending with the whistle. This vocal pattern distinguishes it from the nasal and metallic song of the russet bush warbler and the staccato song of the brown bush warbler. Common calls include a scratchy ksh ksh ksh, a sharp tick, and a stip. The species is structurally similar to the russet bush warbler but is allopatric.

Distribution & Habitat

Endemic to the island of Taiwan. Breeds in mountainous regions from 1,200–3,000 m (3,900–9,800 ft) elevation, occasionally occurring below 1,000 m (3,300 ft). Non-migratory but may move to lower elevations during winter. Inhabits deciduous and coniferous woodland with dense undergrowth of grasses, shrubs, and ferns, as well as grass and bamboo stands near the tree line. Shows some tolerance for human-disturbed habitats.

Behavior & Ecology

Behavior closely resembles that of the russet bush warbler. Primarily diurnal with peak vocal activity in morning and evening hours. Singing begins in late March and continues through the breeding season, with occasional winter song reports. Breeding occurs from May through June, possibly extending to August. Nests are constructed in grass vegetation. Clutch size is two eggs. Diet consists of insects; analysis of stomach contents from the holotype specimen revealed insect remains.

Conservation

Populations are considered common throughout its range. The species is not currently regarded as threatened due to its relatively stable numbers and tolerance of modified habitats. The International Union for Conservation of Nature has assessed it as Least Concern. No specific conservation measures are currently in place.

Source: Wikipedia · CC BY-SA 3.0