Old World Warblers: Family Sylviidae

Old World Warblers are a large family of small birds native to Europe, Africa, and Asia (The Old World). These birds are a welcome European garden visitor, capable of making very pretty, warbling songs. They are normally found in temperate forests throughout Eurasia and some of Africa, and migrate to warmer climates in winter. This family is mostly insectivorous, and has to migrate each year to find winter food sources. Members of this family will generally build their cup-shaped nests in tall grasses or trees, but some nest inside natural cavities.

Taxonomy and Evolution

While this family may look and act very much like the New World Warblers (Parulidae), they are very different genetically. Both families include birds that are small, drab, forest dwelling, migratory birds that primarily eat insects. While these two families are very similar in appearance and habits, they are only distantly related and represent two completely separate diversification events. This is one case where, if it looks like a duck, it quacks like a duck, it still may not be a duck...

New World Warblers are part of a group of birds related to finches, blackbirds, tanagers, and cardinals. They all evolved in South America and radiated north from there. Old World Warblers evolved in Eurasia and are more closely related to swallows.

The reason we are able to see two genetically separate families of birds that look and act so similarly is evolution. Organisms are selected for traits based on the niche they occupy in their habitat, and the various dangers and food resources associated with that habitat niche. In this case, early ancestors of both these families of birds began living in similarly forested habitats. Because there are so many food resources in the from of insects, both of them exploited it. Based on that niche occupation, both families of birds evolved similar characteristics, like a specialized beak and agile flight, to help them catch insects. The process in which organisms independently evolve similar traits based on the habitat they occupy is called convergent evolution.

This family used to contain many more genera but after scientists began studying their DNA, they found many of the species that were included in this family were actually very different. There are now 9 genera, and they include:

Genus Sylvia (Typical Warblers)
Genus Pseudoalcippe (African Hillbabbler)
Genus Rhopophilus (White-browed Chinese Warbler)
Genus Lioparus (Golden-breasted Fulvetta)
Genus Paradoxornis (Typical Parrotbills)
Genus Conostoma (Great Parrotbill)
Genus Fulvetta (Typical Fulvettas)
Genus Chrysomma (3 species)
Genus Chamaea (Wrentit)