Like many other species of ducks that are distinguished by head shape, Common and Barrow’s Goldeneyes are at least as easy to tell apart when sleeping as when they are awake. Birds that are awake and active change head shape a lot as they go from relaxed to alert to diving, but sleeping birds are always about the same. The image below shows the typical appearance of the two species. If you like quizzes you can try to identify them before you read the next paragraph, or just read on for the answer.
Differences in head shape mainly involve the placement and shape of the peak of the head. On Barrow’s the peak is farther forward, and the crown is low, flat, and sloping back to the “mane”. On Common the peak is farther back and taller, rising from the forehead to a rounded triangular peak, then sloping sharply down to the “mane”. In addition, the forehead of Barrow’s is a little steeper and bulging, and the “mane” of Barrow’s is a little longer, all combining to make the head look low and oval, while Common has a more triangular or circular head. In the painting here it’s Common above and Barrow’s below.
If only they would sleep more often…
Would a mnemonic for these be that Common is to Barrow’s Goldeneye as Lesser is to Greater Scaup? Must get down to the river more often to see how readily the distinction can be drawn!