While not common, occasionally closely related birds will mate and produce offspring. Among our three common Teal (Blue-winged, Green-winged, and Cinnamon), hybridization between Blue-winged Teal and Cinnamon Teal is most common.
Since the female ducks are virtually identical, a hybrid female would never be recognized. The male ducks are very different and therefore the male hybridized ducks are identifiable.
At Estero Llano Grande State Park both Blue-winged Teal and Cinnamon Teal are fairly common.
On one of our trips to Estero Llano we came across this Blue-winged x Cinnamon Teal.
Hybrid - Blue-winged Teal x Cinnamon Teal
Note the red eye and body like the Cinnamon Teal and the white crescent like the Blue-winged Teal.