Yellow-billed Teal - Taxonomy

Taxonomy

Mitochondrial DNA sequence data is most similar to that of the very different-looking Green-winged Teal. Apart from the mystifying relationship with the red-and-green-headed teals, it altogether most resembles the Indian Ocean radiation of teals. But the Yellow-billed Teal's unicolored underside and namesake bill are unique, as is to be expected from a species that evolved half a world apart from Bernier's or the Grey Teal.

This species is also unique among its relatives in some aspects of its post-copulation behavior: After dismounting, the drakes stretch themselves up high and swim around and alongside the females.

Traditionally, there are 2 subspecies:

• Sharp-winged Teal, Anas flavirostris oxyptera (Meyen, 1834) – highlands of central Peru to northern Chile and Argentina.
• Chilean Teal, Anas flavirostris flavirostris (Vieillot, 1816) – southern South America as far north as southern Brazil and northern Argentina. Also in the Falkland Islands.

Previously, this species and the Andean Teal formed the superspecies Speckled Teal, but increasingly taxonomists consider the two species distinct.