Red-knobbed Coot
Fulica cristata
The red-knobbed coot is largely black except for the white frontal shield. It is 35–42 cm (14–17 in) long, spans 75–85 cm (30–33 in) across the wings. Males weigh 770–910 g (27–32 oz), females are slightly smaller and weigh 455–790 g (16.0–27.9 oz). The sexes are alike. As a swimming species, it has partial webbing on its long strong toes. The juvenile is paler than the adult, has a whitish breast, and lacks the facial shield; the adult's black plumage develops when about 3–4 months old, but the white shield is only fully developed at about one year old, some time later.
ID text from Wikipedia, CC BY-SA 4.0

White-winged Coot
Fulica leucoptera
The white-winged coot is 35 to 43 cm (14 to 17 in) long and weighs about 400 to 600 g (14 to 21 oz). The sexes are alike. Adults have a yellow to greenish yellow bill and a small yellow to orange-yellow frontal shield, though these colors may further vary. Their legs and feet are pale sea green to yellow-green and have blackish toes and joints. Their plumage is slaty gray that is blacker on the head and neck. They have white undertail coverts, and wide white tips on the secondaries provide the English name. Voice: The white-winged coot is very vocal, making a "variety of loud, hollow cackling calls and clucking notes" some of which sound like human laughter. Aggressive males make a "huc" call.
ID text from Wikipedia, CC BY-SA 4.0
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