The yellowthroats are New World warblers in the genus Geothlypis. Most members of the group have localised ranges in Mexico and Central America, but the Masked Yellowthroat has an extensive South American distribution, and Common Yellowthroat, the only migratory species in the group, breeds over much of North America.
All the yellowthroats have similar plumage, with yellow-green upperparts, yellow breast, and a mainly black bill. The adult male has a black facemask of variable extent, usually bordered above with a grey band. The female is similar, but lacks the black mask, and may be duller in plumage.
The breeding habitat of these warblers is typically marshes and other wet areas with dense low vegetation. The eggs, two in most species, but up to five for Common Yellowthroat, are laid in a lined cup nest low in grass or rank vegetation.
The taxonomy of these closely related species is complicated, and it is sometimes difficult to define which forms merit species status. For example Common Yellowthroat, Belding's Yellowthroat, Altamira Yellowthroat, and Bahama Yellowthroat are sometimes considered conspecific. Conversely Masked Yellowthroat can be split to three or even four species.
The geographical isolation of the various populations of this mainly sedentary group has led to its genetic divergence and speciation. This process can be seen in action in the case of Masked Yellowthroat, where the subspecies are separated by rainforest or the Andes, leading to the development of distinctive forms, such as the Central American race Geothlypis aequinoctialis chiriquensis. This form is found in the highlands of Costa Rica and western Panama, and is separated by 1000km from its South American cousins, from which it differs in size, appearance and vocalisations.