The Saipan reed warbler or gå'ga' karisu in Chamorro is an endangered songbird of the Northern Mariana Islands.
Region
Micronesia (Northern Mariana Islands)
Typical Environment
Occurs mainly on Saipan and also on Alamagan, inhabiting reedbeds, wetlands, and adjacent thickets. It uses native marsh vegetation and dense secondary scrub, as well as some introduced thickets such as tangantangan. The species forages along wetland edges, in riverine vegetation, and in dense grass or vine tangles. Following major typhoons, birds may shift into surviving pockets of dense cover until habitat regenerates.
Altitude Range
Sea level to 500 m
Climate Zone
Tropical
Ease of Keeping
Beginner friendly: 1/5
Also known in Chamorro as gå'ga' karisu, this reed-warbler is confined to the Northern Mariana Islands, chiefly Saipan and Alamagan. It is threatened by habitat loss, severe typhoons, and invasive predators; the potential arrival of brown tree snakes poses a grave risk. Conservation actions focus on habitat protection, predator control, and safeguarding populations from storm impacts.
Temperament
secretive and territorial
Flight Pattern
short rapid wingbeats low over vegetation
Social Behavior
Generally seen singly or in pairs during the breeding season, defending small territories in dense cover. Builds a cup nest in reeds or thick shrubs, often close to water. Clutches are small and both parents participate in feeding the nestlings.
Migratory Pattern
Resident
Song Description
A loud, buzzy and chattering warble delivered from concealed or semi-exposed perches. Phrases are variable, with scratchy notes interspersed with harsher churring calls.
Plumage
Warm brown upperparts with paler, buffy underparts and a slightly paler throat; plumage appears plain but with subtle streak-free tones typical of reed-warblers.
Diet
Primarily feeds on insects such as beetles, caterpillars, grasshoppers, and dragonflies, as well as spiders. It gleans prey from reed stems, leaves, and tangled vines, and may sally short distances to catch flying insects. Occasional small arthropods are taken from the ground or low foliage.
Preferred Environment
Forages in dense reeds, sedges, and scrub bordering wetlands and streams. Also uses secondary thickets and vine tangles where cover is continuous and humid.
