The redwing (Turdus iliacus) is a bird in the thrush family, Turdidae, native to Europe and the Palearctic, slightly smaller than the related song thrush.
Taxonomy and systematics
This species was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae under its current scientific name.
The English name derives from the bird's red underwing. It is not closely related to the red-winged blackbird, a North American species sometimes nicknamed "redwing", which is an icterid, not a thrush. The binomial name derives from the Latin words turdus, "thrush", and ile "flank".
About 65 species of medium to large thrushes are in the genus Turdus, characterised by rounded heads, longish, pointed wings, and usually melodious songs. Although two European thrushes, the song thrush and mistle thrush, are early offshoots from the Eurasian lineage of Turdus thrushes after they spread north from Africa, the redwing is descended from ancestors that had colonised the Caribbean islands from Africa and subsequently reached Europe from there.
The redwing has two subspecies: Adults moult between June and September, which means that some start to replace their flight feathers while still feeding young.
Song
The male has a varied short song, and a whistling flight call. Redwings show a distinct dialectic variation in song, having a considerable similarity in song patterns among birds within a local population.
The Redwing song consists of a number of introductory elements of descending or ascending frequency. These elements may be of pure tonal quality, or of a more harsh quality (varying degrees of frequency modulations or "trills"). After the introductory elements, a fast and more complex song pattern often follows. It is the introductory elements which show a geographic variation. The boundaries of any given dialect may vary but in a rural and forested environment in Norway the average size of these dialect areas is around 41.5 km2.
The thrush is migratory, wintering in western, central and southern Europe, north-west Africa, and south-west Asia east to northern Iran. Birds in some parts of the west of the breeding range (particularly south-western Norway) may be resident, not migrating at all, while those in the far east of the range migrate at least 6,500–7,000 km to reach their wintering grounds.
Migration occurs between autumn and early winter, and the birds often move at night. Oftentimes, they may make a "Tseep" contact call that can carry a long distance.
Status and conservation
The redwing has an extensive range, estimated at 10 million square kilometres (3.8 million square miles), and an estimated population of 26 to 40 million individuals in Europe alone. The European population forms approximately 40% of the global population, thus the very preliminary estimate of the global population is 98 to 151 million individuals. The species is believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e., declining more than 30% in ten years or three generations), and is therefore precautionarily uplisted to near threatened.