Masked Yellowthroat - Taxonomy

Taxonomy

There are five subspecies of the Masked Yellowthroat, differing in size, male head pattern and song. The Central American subspecies is sometimes considered a separate species, and the two Pacific subspecies together are also often treated as a species. Recent genetic evidence suggests that the southern South American subspecies may also merit specific status. The populations are as follows:

• The nominate race, G. a. aequinoctialis, described above, breeds from central Colombia, through northern Venezuela, Trinidad, the Guianas, to the regions near the Amazon River in Brazil. The song is a warbled tee-chee-chee teecheweet teecheweet.
• G. (a). velata, the “Southern Yellowthroat”, breeds in central South America from south-eastern Peru and adjacent parts of Brazil, through Bolivia, Paraguay, Uruguay and southern Brazil, to central Argentina. It is slightly smaller than aequinoctialis, and the male has a narrower black mask, with a broader grey band which extends onto the nape and neck sides. The song is longer, faster and more warbled than that of the northern race.
• G. (a). auriculata and G. a. peruviana, the “Black-lored Yellowthroat”, breeds in western Ecuador and western Peru. The male has the black mask restricted to the area from the bill back to the eye and a narrow band on the forehead. The subspecies peruviana, which is found in the Marañón valley, is similar in size to aequinoctialis, but auriculata is noticeably smaller. The song of is a cheerful wee wee wee weeyou weeyou.
• G. (a). chiriquensis, the “Chiriqui Yellowthroat”, occurs in western Panama and Costa Rica. It is another small form, but the male has the broadest black mask of all the races, extending on to the forecrown. The song is similar to auriculata, but repeated many times, becoming faster, higher and weaker before a final flourish, and it may be given in flight.

It is likely that the range of this species was once continuous, perhaps in the cooler conditions of the last ice age, but the populations are now separated by the dense sections of wet lowland forests of the Amazon and Chocó. The auriculata and chiriquensis groups are further separated from the nominate and velata groups by the Andes Mountains.