This endangered Hawaiian endemic species has a total population between 2,000 &4,000, with 80% on Kauai, Oahu, and Maui. They were formerly considered to be a subspecies of the American Coot, but split as a separate species by the AOU in 1993. The wildlife manager of the golf course took me to an area where there were about 60 of these endangered coots. This species is polymorphic with respect to shield color. Most had the frontal shield all white but one bird had a dark red frontal shield (bottom photos). One study found that only about 2% of the total population has the red frontal shield, but other sources give a higher estimate. These red-shield birds also have dark subterminal spots on the bill and more colorful greenish legs as seen here rather than the more typical gray of the white shielded birds. In these respects they seem more like American Coots. Canon PowerShot SX60 HS.
References:
Pratt, H. D. and I. L. Brisbin Jr. (2002). Hawaiian Coot (Fulica alai), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.697b
Pratt, H.D., Bruner, P., and Berrett, D.G. (1987) A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press.
Pyle, R.L., and P. Pyle. 2017. The Birds of the Hawaiian Islands: Occurrence, History, Distribution, and Status. B.P. Bishop Museum, Honolulu, HI, U.S.A. Version 2 (1 January 2017) http://hbs.bishopmuseum.org/birds/rlp-monograph/
Taylor, B. & Sharpe, C.J. (2020). Hawaiian Coot (Fulica alai). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/53696 on 28 January 2020).