Old World Warblers (Sylviidae)
The Old World warblers are included in one of the one hundred eighteen families of birds in the order PASSERIFORMES (pronounced pas-ser-i-FOR-meez); a large taxonomic order that includes other small birds such as the kinglets, and large birds such as the crows and jays.
In the Sylviidae (pronounced sil-VEYE-uh-dee) family, a group with a nearly worldwide distribution, there are two hundred sixty-six species of Old World warblers and gnatcatchers in thirty-three genera, although some authorities split this large family into several smaller families (IOC World Bird List, version 2.3).
In Europe, forty-four species in seven genera of the Sylviidae family have occurred. Counted among these are common species like the Blackcap, Willow Warbler, and Whitethroat, and several vagrants to Europe from Asia such as the Yellow-browed, Pallas’s, and Radde’s Warblers. (It should be noted that an ongoing debate about splitting up the Sylviidae family may greatly reduce the number of species classified as such, thereby reducing the number of European species still so classified as Sylviidae to nineteen in one genus.)
The warblers are known for their active mannerisms and in being small birds that can be very challenging to identify.
Members of the Sylviidae are small birds with fairly long legs, and strong feet that suit their arboreal nature. They have thin, medium length bills, rather short wings, and most have somewhat long tails which are rather wedge shaped in the warblers of the Locustella and Acrocephalus genera.
The many members of the Sylviidae are predominantly dull-coloured, difficult to identify birds. Browns and greys are the common colour theme, though some also have black in their plumage. Brighter colours are restricted to reddish or yellow underparts and red eye rings shown by some species. Several of the Sylviidae also show white markings on the face as well as on the wings and tail.
In Europe, the Sylviidae occur just about everywhere except on the highest of mountains and on the northernmost tundra. The many members of this family occupy both deciduous and coniferous forests, Mediterranean scrub, and a variety of wetland habitats.
Most warbler species are long distance migrants to sub-Saharan Africa and southern Asia.
The members of the Sylviidae do not nest in colonies but often join mixed species flocks of small birds that forage together for protection from predators. They forage for invertebrates by gleaning them from the vegetation of trees and bushes.
In Europe, the most threatened Sylviidae species is the Aquatic Warbler. This wetland species has greatly declined in Europe because its required habitat of waterlogged, sedge meadows are easily and frequently drained. The last stronghold for this species is in eastern Poland and possibly some areas in eastern Russia.
Although the plumages of warblers can be confusing for beginning and advanced birders alike, the calls and songs of most species are distinctive and are often a more reliable reference for their identification in the field. As with many birds, the vocalizations of warblers are fairly species specific, a fact that has helped clarify species level classification in this family.