Great Reed Warbler
Acrocephalus arundinaceus
A hulking warbler that resembles Eurasian Reed-Warbler in coloration but far larger with a proportionately more massive head, heavy bill with a dark tip, and a broad, pale eyebrow. Breeds in reed beds, crashing through the reeds in short flights and bending stems when perched. Non-breeding habitat includes wet marshy areas, as well as drier habitats such as agricultural fields, savanna, and low scrubby growth. Song short but very loud and memorable with repeated phrases of "karra-karra-karra gurk gurk gurk chirrr-chirrr karra karra." Call a high-pitched “krrrrr."
Identification
The thrush-sized warbler is one of the largest species of the former family, the Old World warblers and it stands as one of the largest species in the family Acrocephalidae. It measures 16–21 cm (6.3–8.3 in) in length, 25 to 30 cm (9.8 to 11.8 in) in wingspan and weighs 22 to 38 g (0.78 to 1.34 oz). The adult has unstreaked brown upperparts and dull buffish-white chin and underparts. The forehead is flattened, and the bill is strong and pointed. It looks very much like a giant Eurasian reed warbler (A. scirpaceus), but with a stronger supercilium.<p>The sexes are identical, as with most old world warblers, but young birds are richer buff below.<p>The warbler's song is very loud and far-carrying. The song's main phrase is a chattering and creaking carr-carr-cree-cree-cree-jet-jet, to which the whistles and vocal mimicry typical of marsh warblers are added.
Taxonomy
Genus: Acrocephalus; Family: Acrocephalidae; Order: Passeriformes.
- Scientific name
- Acrocephalus arundinaceus
- Authority
- (Linnaeus, 1758)
- Order
- Passeriformes
- Family
- Acrocephalidae
- Genus
- Acrocephalus
Range and habitat
The great reed warbler breeds in Europe and the west Palearctic. It does not breed in Great Britain, but is an irregular visitor. Its population has in recent decades increased around the eastern Baltic Sea, while it has become rarer at the western end of its range. It is a migratory bird, wintering in tropical Africa. This bird migrates north at a rather late date, and some birds remain in their winter quarters until the end of April.<p>While there are no subspecies of this bird, mtDNA haplotype data indicate that during the last glacial period there were two allopatric populations of great reed warbler. The great reed warblers in southwestern and southeastern Europe were at that time apparently separated by the Vistulian-Würm ice sheets and the surrounding barren lands. Though the data are insufficient to robustly infer a date for this separation, it suggests the populations became separated around 80,000 years ago – coincident with the first major advance of the ice sheets. The populations must have expanded their range again at the start of the Holocene about 13,000 years ago, but even today the western birds winter in the west and the eastern birds in the east of tropical Africa.<p>During 2017–2019, miniature data loggers were used to track migratory flights of great reed warblers, over the Mediterranean Sea and Sahara Desert, between their breeding grounds at Lake Kvismaren, Sweden, and their winter quarters in sub-Saharan Africa. When over the Sahara Desert, some birds would ascend to altitudes exceeding 5 km. As of 2023, these are the highest recorded avian ascents. For comparison, such altitudes are comparable to those of the summits of the highest mountains in Africa and Europe. Possible explanations for such high--altitude ascents include avoidance of predation, reduction of risk of hyperthermia and dehydration, and extension of the visual horizon. <p><p>This passerine bird is found in large reed beds, often with some bushes. On their breeding grounds, they are territorial. In their winter quarters, they are frequently found in large groups, and may occupy a reed bed to the exclusion of other birds. Like most warblers, it is insectivorous, but it will take other prey items of small size, including vertebrates such as tadpoles.<p>The great reed warbler undergoes marked long-term population fluctuations, and it is able to expand its range quickly when new habitat becomes available. This common and widespread bird is considered a species of least concern by the IUCN. Population size can be calculated with a suitability model, but direct counts of territorial males in suitable habitat and sampling the population sex-ratio can be a proper alternative to inference-rich predictive modeling based on imperfect habitat-extrapolation of densities of reed warblers at large spatial scales.
- Migration
- Complete migrants
Behavior
Migration pattern: Complete migrants.
Conservation
Population trend: declining.
- Population trend
- declining
Photos
Distribution
Bird Calls
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