This is a retroactive split - Oxyura ferruginea was added when it should have been split off from Oxyura jamaicensis. We are now splitting Oxyura jamaicensis after the fact to sort out existing identifications of Oxyura jamaicensis that now apply to Oxyura ferruginea
Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2018. The eBird/Clements checklist of birds of the world: v2018. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/ (連結)