^ Hoatzin, New World vultures, Secretarybird, raptors , Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.1). https://doi.org/10.14344/IOC.ML.10.1 . (Downloaded 26 May 2020) ^ Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, B. L. Sullivan, and ...