Two genera, Myioborus and Basileuterus, seem to have colonized South America early, perhaps before the two continents were linked, and together constitute most warbler species of that region.

[5] A molecular phylogenetic study of the Parulidae published in 2010 found that the species formed several major clades that did not align with the traditional genera.

[1][2] The genus Myioborus containing the whitestarts remained unchanged after the reorganization but six genera were no longer used: Dendroica, Ergaticus, Euthlypis, Parula, Wilsonia and Phaeothlypis.

The migratory species tend to lay larger clutches of eggs, typically up to six, since the hazards of their journeys mean that many individuals will have only one chance to breed.

In contrast, the laying of two eggs is typical for many tropical species, since the chicks can be provided with better care, and the adults are likely to have further opportunities for reproduction.

The Parkesia waterthrushes and ovenbird are strongly migratory, but have identical male and female plumage, whereas the mainly tropical and sedentary yellowthroats are dimorphic.

The Granatellus chats also show sexual dimorphism, but due to recent genetic work, have been moved into the family Cardinalidae (New World buntings and cardinals).