Black
& Common Scoter: What To Listen For
1. Black Scoter has a courtship call of much longer
duration (in Sangster’s samples
694±168 versus 106±12milliseconds) than that of Common Scoter-Although the usefulness of this vocalization in
identification will be extremely limited (how often have you heard Black Scoter’s courtship call?) the dramatic
difference in length of the courtship call was instrumental in gaining acceptance of the proposed split
under the “biological species concept”. George Sangster argues (The Wilson Journal of Ornithology
121(4): 696-702, 2009) that the huge difference in these calls given by males as they swim in circles
around a single female would preclude the forms interbreeding if their ranges overlapped in the wild.