The black line extending beyond the eye remembers the slanted eye of Asian people. The yellow-billed pintail lacks this line. This is one of the characteristics which tell apart these two confusables.
Two ducks which make beginners doubt. Since they are together, let's see the differences in head and neck.
Yellow-billed Teal has all its head dark brown. Short and robust neck. The eye is crossed by a black line which resembles a slanted eye.
Yellow-billed Pintail has reddish cinnamon crown and face and neck whitish. Slimmer and longer neck.
And the yellow-billed pintails are back, too. A very common duck at the reserve and almost last to arrive now that the pond is with water. There is another absentee the cinnamon teal. On the left a silver teal
A yellow-billed pintail with a pair of yellow-billed teals, two species that lead to confusion