The Aguiguan reed warbler or Aguijan reed warbler is an extinct bird that originally occurred on the Northern Mariana Island Aguigan. It is considered a subspecies of the nightingale reed warbler by some taxonomists. Of this subspecies there never have been reports of a substantial population. In 1982 only four up to possibly 15 birds of the subspecies have been counted, and since 1995 none has been sighted, despite extended efforts to find specimens.
Region
Micronesia, Western Pacific
Typical Environment
This bird was restricted to Aguiguan (Aguijan), a small, arid limestone island with patchy native forest, tangantangan thickets, and grass-shrub mosaics. It favored dense undergrowth, vine tangles, and forest edges where it could forage low to mid-level in cover. The island lacks extensive wetlands, so the species adapted to coastal scrub and secondary growth rather than true reed marshes. Habitat degradation from browsing by feral ungulates and vegetation change likely reduced suitable nesting and foraging areas. Extreme weather events in the typhoon belt may have further impacted the tiny population.
Altitude Range
Sea level to 160 m
Climate Zone
Tropical
Ease of Keeping
Beginner friendly: 1/5
The Aguiguan (Aguijan) reed warbler was confined to a single, small limestone island in the Northern Mariana Islands and is widely considered extinct. Some authorities treat it as a distinct species (Acrocephalus nijoi), while others regard it as a subspecies of the Nightingale Reed Warbler. It inhabited dense scrub and thickets rather than classic reedbeds, and was always scarce; targeted surveys since 1995 have failed to locate any survivors.
Temperament
secretive and skulking
Flight Pattern
short rapid wingbeats, typically low over vegetation
Social Behavior
Likely formed monogamous pairs during the breeding season, defending small territories in dense thickets. Nests were presumably cup-shaped and placed low in shrubs or tangles, as in related Acrocephalus species. Outside breeding, it remained elusive and was seldom seen in groups.
Migratory Pattern
Resident
Song Description
A varied warble with scratchy, churring notes delivered from concealed perches within dense cover. Calls were sharper chips used for contact and alarm, with the song becoming more persistent during the breeding period.
