Parrotbill
The parrotbills are a family, Paradoxornithidae, of passerine birds that are primarily native to East and Southeast Asia (with a single species in western North America), though feral populations exist elsewhere. They are generally small, long-tailed birds that inhabit reedbeds and similar habitat. They feed mainly on seeds, e.g. of grasses, to which their bill, as the name implies, is well-adapted. Living in tropical to southern temperate climates, they are usually non-migratory.
The bearded reedling or "bearded tit", a Eurasian species long placed here, is more insectivorous by comparison, especially in summer. It also strikingly differs in morphology, and was time and again placed in a monotypic family Panuridae. DNA sequence data supports this.
As names like "bearded tit" imply, their general habitus and acrobatic habits resemble birds like the long-tailed tits. Together with these and others they were at some time placed in the titmouse family Paridae. Later studies found no justification to presume a close relationship between all these birds, and consequently the parrotbills and bearded reedling were removed from the tits and chickadees and placed into a distinct family. As names like Paradoxornis paradoxus – "puzzling, paradox bird" – suggest, their true relationships were very unclear, although by the latter 20th century they were generally seen as close to Timaliidae ("Old World babblers") and Sylviidae ("Old World warblers").
Since 1990 (Sibley & Ahlquist 1990),[1] molecular data has been added to aid the efforts of discovering the parrotbills' true relationships. As Paradoxornis species are generally elusive and in many cases little-known birds, usually specimens of the bearded reedling which are far more easy to procure were used for the analyses. Often, the entire group was entirely left out of analyses, being small and seemingly insignificant in the large pattern of bird evolution (e.g. Barker et al. 2002, 2004). The bearded reedling tended to appear close to larks in phylogenies based on e.g. DNA-DNA hybridization (Sibley & Ahlquist 1990), or on mtDNA cytochrome b and nDNA c-myc exon 3, RAG-1 and myoglobin intron 2 sequence data (Ericson & Johansson 2003). Placement in a superfamily Sylvioidea which contained birds such as Sylviidae, Timaliidae and long-tailed tits – but not Paridae – was confirmed.
Cibois (2003a) analyzed mtDNA cytochrome b and 12S/16S rRNA sequences of some Sylvioidea, among them several species of Paradoxornis but not the bearded reedling. These formed a robust clade closer to the Sylvia typical warblers and some presumed "Old World babblers" such as Chrysomma sinense than to other birds. The puzzle was finally resolved by Alström et al. (2006), who studied mtDNA cytochrome b and nDNA myoglobin intron 2 sequences of a wider range of Sylvioidea: The bearded reedling was not a parrotbill at all, but forms a distinct lineage on its own, the relationships of which are not entirely resolved at present. The parrotbills' presence in the clade containing Sylvia, on the other hand, necessitates that the Paradoxornithidae are placed in synonymy of the Sylviidae. Cibois (2003b) even suggested that these themselves were to be merged with the remaining Timaliidae and the latter name to be adopted. This has hitherto not been followed and researchers remain equivocal as many taxa in Sylviidae and Timaliidae remain to be tested for their relationships. In any case, it is most likely that the typical warbler-parrotbill group is monophyletic and therefore agrees with the modern requirements for a taxon. Hence, whether to keep or to synonymize it is entirely a matter of philosophy, as the scientific facts would agree with either approach.
