The parrotbills are a family, Paradoxornithidae, of passerine birds that are primarily native to East, Southeast and South Asia, with a single species in western North America, though feral populations exist elsewhere.

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 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.

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.

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 interesting conclusion from an evolutionary point of view is that the morphologically both internally homogenous and compared to each other highly dissimilar typical warblers and parrotbills form the two extremes in the divergent evolution of the Sylviidae.

How dramatic the evolutionary changes wrought upon the parrotbills in their adaptation to feeding on grass caryopses and similar seeds were can be seen by comparing them with the typical fulvettas, which were formerly considered Timaliidae and united with the alcippes (Pasquet 2006).

It is based on the results of the molecular phylogenetic study by Tianlong Cai and collaborators and the generic divisions adopted by Frank Gill, Pamela Rasmussen and David Donsker in the list of birds maintained on behalf of the International Ornithological Committee.

[5] The common cuckoo lays its eggs in the nests of parrotbills and the two have co-evolved together over time to promote the reproductive success of both species.

[6] The common cuckoo is an example of an avian brood parasite that reduces the energy cost of caring for its eggs by placing them in the parrotbill's nest.

[6] Over time, the two species co-evolve with the parrotbill first utilizing one of the hypothesized cognitive mechanisms in order to recognize parasitic eggs.

[5] In order to compensate for this new behaviour in parrotbills, the parasite produces eggs that are similar to those of the host and leads to the evolution of polymorphisms over time for both species.