The Mangareva reed warbler or Astrolabe reed warbler is a presumed extinct songbird that existed on Mangareva in the Gambier Islands. It is known from only two specimens, and is believed to have gone extinct in the mid-19th century, likely due to deforestation and the introduction of exotic predators.
Region
South Pacific Ocean
Typical Environment
Endemic to Mangareva in the Gambier Islands, it most likely occupied dense vegetation near freshwater and brackish wetlands, including reedbeds and marshy margins of the island’s lagoon. Like related island reed warblers, it probably foraged in coastal thickets of Hibiscus and Pandanus and along forest edges. Secondary scrub and coconut groves would also have provided cover and foraging substrates. Suitable habitat would have been patchy, making the species vulnerable to clearance and degradation.
Altitude Range
Sea level to 400 m
Climate Zone
Tropical
Ease of Keeping
Beginner friendly: 1/5
Known from just two 19th‑century specimens, the Mangareva reed warbler likely vanished soon after human-driven habitat changes and the arrival of invasive predators. It belonged to the Pacific radiation of Acrocephalus reed warblers, many of which evolved separately on remote islands. Its common name “Astrolabe” references the French exploration ship that collected the specimens. Virtually nothing is known from life, so most ecology is inferred from closely related island reed warblers.
Temperament
solitary and territorial
Flight Pattern
short rapid wingbeats through dense vegetation
Social Behavior
Probably formed monogamous pairs during the breeding season, defending small territories in dense cover. Nests in related species are cup-shaped and suspended in reeds or placed low in shrubs, which is likely for this species as well. Clutch sizes of 2–3 eggs are typical among island Acrocephalus warblers.
Migratory Pattern
Resident
Song Description
Likely a scratchy, chattering warble delivered from concealed perches within reeds or shrubs. Song probably included repeated phrases and mimicry elements, as in many Acrocephalus species.
Plumage
Presumed plain reed-warbler pattern: warm brown upperparts with paler, buffy underparts and a slightly paler throat.
Diet
Primarily small insects and other arthropods gleaned from foliage, reed stems, and low shrubs. It may have taken spiders and soft-bodied larvae and occasionally snatched flying insects in short sallies. Like some related island forms, it could have opportunistically eaten small berries or nectar, but invertebrates would have dominated.
Preferred Environment
Foraged along wetland edges, reedbeds, and in dense coastal or secondary thickets. It likely worked the lower to mid-strata, moving methodically through cover while gleaning prey.
