—By Mike Brasher, Ph.D.
The roughly 150 species of ducks, geese and swans
that occur around the world display an amazing variety of physical features and behaviors. Across this array of waterfowl, some species are more closely related than others. Scientists use behavior, anatomy and sophisticated genetic analyses to classify related birds into groups that reflect these relationships. For example, essentially all dabbling ducks belong to the genus Anas
, while diving ducks belong to the genus Aythya
But even within the same genus, scientists can identify subgroups that possess greater degrees of ancestral relatedness. The "blue-winged ducks" are a prime example. This group includes three North American species—northern shovelers, blue-winged teal and cinnamon teal—as well as four species found in other parts of the world.
Waterfowlers and other bird enthusiasts have likely noticed the similar, striking blue wing patches on northern shovelers and blue-winged teal. Their close relative, the cinnamon teal, also has similar wing markings, but is less widely known because of its small population size and limited range, which is largely confined to the Pacific Flyway
. Closer inspection of the life histories of these species reveals amazing similarities beyond physical appearance.