The Australian reed warbler (Acrocephalus australis ) is an Old World warbler in the genus Acrocephalus and is the only Acrocephalus species native to Australia. It has also been observed in Papua New Guinea and nearby islands. The name Acrocephalus refers to the peaked crown found on reed warblers in this genus and can be translated to mean "topmost head" in Greek. The species name australis is translated to mean "southern" in Latin, and refers to the species range, Australia. In its western range the Australian reed warbler is also known as "Koordjikotji" pronounced core’chee’caw’chee in the Perth area and surrounds in local Aboriginal language.
Australian reed warblers are found in a wide range of natural and man-made wetlands including fresh, brackish and saltwater environments. Dense vegetation with vertical structures such as; reeds (Phragmites ), reedmace (Typha ) and rushes (Juncus ) are frequented in breeding and non-breeding season and Australian reed warblers are often observed perched sideways midway along a reed stem. This species is occasionally observed in shrub lands and riparian woodlands surrounding water bodies where it can be observed foraging.
This species forages mainly individually but sometimes in pairs, in dense vegetation on insects and spiders and occasionally molluscs and seeds. The Australian reed warbler forages amongst dense riparian vegetation and in surrounding shrubs and woodlands where it can be seen gleaning arthropods from vegetation. This species is also known to sometimes forage on open mud near reeds and rushes.
This species forms a socially monogamous seasonal breeding pair, nest building and chick feeding are carried out by the pair for the season. The same male and female pairings are not typically repeated in following seasons. Australian reed warblers are known to be polygynous/polyandrous and engage in extra-pair copulations. Unlike all other Acrocephalus species which are sedentary, the Australian reed warbler migrates seasonally. The Australian reed warbler migrates to South West and South East Australia to breed from overwinter grounds throughout Eastern and Northern Australia. Males arrive at the breeding grounds from July to August onwards. Breading season is October to December in south-eastern Australia and September to December in southern Australia. Males and females build the nest, however females contribute more than males. The nest is a deep cup (6.4 – 9 cm diameter and 7 – 18.5 cm height) made from dead and fresh vegetation usually supported by fresh and dead reed stems found between 30–200 cm off the ground or water surface. Incubation is carried out by the female for 13 – 15 days and clutch size is between 2-4 eggs. Chicks are fed by both the male and female in the nest for a period of 10–13 days and parents continue to feed fledglings outside the nest until they are more than 28–29 days old. Australian reed warblers have a nesting success of 58%, nest predation is the major cause of nesting losses.
