Systematics
The Wrentit has been variously placed in its own family, the Chamaeidae, or with the long-tailed tits (Aegithalidae), the true tits and chickadees (Paridae), the "Old World warblers" (Sylviidae), and with the "Old World babblers" (Timaliidae). The American Ornithologists' Union places the Wrentit in the latter family, giving it the distinction of being the only babbler known from the New World. This is based on DNA-DNA hybridization studies, which are phenetic however and therefore not considered methodologically adequate today.
Through DNA sequence analysis, it was subsequently discovered that the Wrentit was more closely allied to Sylvia warblers and some aberrant "babblers". These consequently must be placed in the Sylviidae family together with the Wrentit and the parrotbills which also turned out to be close relatives. Thus, the Wrentit is the only American species of the "true" or sylviid warblers. Peculiarly, the Dartford Warbler and close relatives like Marmora's Warbler bear an uncanny resemblance to the Wrentit; their ecology is quite similar indeed as all are birds of Mediterranean scrub. However, biogeography and the molecular data build a strong case for this similarity being a case of convergent evolution between birds that are close relatives but by far not as close as their appearance would suggest.
Alice Cibois suggested that as some babblers are closer to typical warblers than these are to marsh-warblers for example, the Sylviidae should be merged into the Timaliidae. As such an abolishing of the senior synonym would require a formal International Commission on Zoological Nomenclature ruling and the typical warblers and relatives are still a monophyletic group at present, this proposal is not advanced by most researchers until the remaining Sylviidae and Timaliidae genera are studied as regards their relationships.
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