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THRUSHES Turdidae
Species in family 173
Species observed [DR] 85 (49%)
Species photo'd [DR] 22
Thrushes are small to medium-sized songbirds that have ten primaries and a turdine 'thumb' on the syrinx. Many are accomplished songsters, and some have vocalizations that are among the most lovely on earth. It has been difficult to define this family as its boundaries are constantly changing in the ornithological literature. Keith, Urban & Fry's (1992) Birds of Africa said: "We prefer to retain Turdidae as a family until its relationships with sister groups are worked out, while recognizing that this is probably in part an artificial grouping." When I first created this page in 1999, the Turdidae were a huge family of 365 species. Recently, many authors are taking the approach used by the 3d ed. Howard & Moore Checklist (Dickinson 2003) in placing the 180 or so "chats" and relatives within the Muscicapidae [Old World Flycatchers]. I now follow this trend and restrict the Turdidae to 173 species in 20 to 24 genera of "true thrushes." The family still retains the familiar genus Turdus — examples of which include the widespread and familiar American Robin T. migratorius and Eurasian Blackbird T. merula — and a host of others including bluebirds, solitaires, whistling-thrushes, alethes, and shortwings.
By far the largest group within our restricted Turdidae are in the 65 species within the genus Turdus. These birds are native to all continents except Australia and Antarctica. Some are common, others are widespread [Island Thrush T. poliocephalus has 51 subspecies scattered widely across the Pacific and on New Guinea and Borneo], but many are scarce and local. One of the latter is Kessler's Thrush (left or above) whose breeding range is restricted to north China.
This Groundscraper Thrush (right) is a South African thrush photographed as it battled its own reflection in a auto windshield. It is most often retained within a monotypic genus (Psophocichla), of of ten such monotypic families within the Turdidae. Another is the strange and unique Fruithunter Chlamydochaera jefferyi, endemic to the mountains of northern Borneo. For many years it was not known how this pigeon-shaped thrush was related to other birds; details of its nest and song have only recently been published.
Thrushes and their sister groups have been treated taxonomically in many different ways over the past half-century. They were once considered a part of a huge group including Old World flycatchers, Old World warblers, babblers and allies (Mayr and Amadon 1951). Later the grouping was restricted but still included the batises, monarchs, and whistlers (Wetmore 1960) which are now thought of as separate families. Sibley & Ahlquist (1990) and Sibley & Monroe (1990) created a huge Muscicapidae with two subfamilies -- the 'true thrushes and the rest, which were divided into two tribes, the 'chats' and the Old World flycatchers. Clements (1991) sort-of followed this approach. But if Sibley & Ahlquist's DNA evidence is correct, that grouping ('true thrushes' and 'chats' together but excluding Old World flycatchers) is polyphyletic. There is no genuine consensus as yet, but the restricted arrangement now adopted here seems best. Even this approach is not without problems at the edges: following recent authorities like Keith, Urban & Fry (1992), Urban, Fry & Keith (1997) and (Christy & Clarke 1998), I exclude Chaetops (rock-jumpers) and Horizorhinus (the endemic Dohrn's Thrush-Babbler of Príncipe) from thrushes and consider them (tentatively) to be, respectively, a separate family [Chaetopidae] and a babbler.
Setting aside these taxonomic quagmires, let's just review the basics of the thrush family. A typical example is the American Robin (below left; at nest with young). These large thrushes sing lovely songs; they hop on lawns listening for earthworms and pull them from the soft earth; and their nests can often be easily found. Indeed, they are considered a harbinger of spring in many places. There are Turdus thrushes in most wooded habitats around the world. North American woods and riparian habitats have members of the genus Catharus (e.g., Hermit, Swainson's, Gray-cheeked & Bicknell's thrushes, Veery) whose spiraling melodies (some species upscale, others downscale) are among the most beautiful sounds of summer. One of those species — Hermit Thrush — is shown (below right). On migration, when they are silent except for flight notes and calls, members of this group can be very difficult to separate visually, especially as vagrants. Wood Thrush Hylocichla mustelina of eastern North America is another fine singer.
Included in the true thrushes re a wide range of species with more limited vocal repertoires. These are the Zoothera thrushes of the Old World, and their New World relatives Aztec Thrush Ridgwayia pinicola and Varied Thrush (below). These are an ancient lineage of mostly sedentary, secretive, easily-overlooked forest species (a good summary of the African species, including identification, is in Clement 1999). The Varied Thrush of western North America breeds in dark woods of the northwest and is so shy that it's prolonged note on a minor scale is often the only evidence it is around. The particular individual shown below was a vagrant in Death Valley. It is a very odd individual and must have been an immature female (lacking a breastband) but it also lacked all orange tones on the breast and supercilium. It is an example of schizochroism: washed-out plumage from a lack of a pigment. Oddly enough, the only vagrant Varied Thrush to reach the British Isles was another schizochroistic individual.
In contrast, the North American bluebirds (genus Sialia) are often conspicuous in open country. The lovely sky-blue color of a male Mountain Bluebird (right) especially stands out against the usually pale background that it inhabits: high-elevation plains and meadows in the summer, dry barren grasslands in the winter. I like this shot of a blue bird against a blue sky on a gleaming white old-style grave stone. As it happens, it is only Mountain Bluebird ever to have wintered along the coast of Monterey County, my home county in central California.
Tropical forests also have their share of thrushes. In south Asia, the Greater Sundas, and Taiwan are 7 species of whistling-thrush (genus Myophonus); shown (below left) is Blue Whistling-Thrush which frequents the Himalayas, often found along rushing streams. In Neotropical woods there are often one or more species of solitaires (Myadestes) — exceptional songsters that are much easier to hear than to see. The backlit singer shown (below right) is Rufous-throated Solitaire, a secretive bird of montane forests in the West Indes.
There were once six species of Myadestes in Hawaii, but four, and probably five, are now extinct.