The Eastern and Western subspecies of Warbling Vireo come in contact along the Front Range of Colorado. The differences in appearance between the two subspecies are subtle and require a close look. The songs of breeding males, who seem to sing continuously, are easier to differentiate. Eastern birds are usually described as more sing-songy or melodic and thus are the form that gave the species its common name. Western birds are described as singing choppy or buzzier songs. The song oftern ends on a higher note. Andrew Spencer put together a nice tutorial on how to distinguish the Warbling vireo subspecies.
The Western song tends to have more higher pitched notes and has a less sing-songy quality.
Click the play button to listen to the audio file. Select your answer using the radio buttons. The result of your answer will be presented to you. Move through the quiz using either the next buttons or the arrows at the top of the page.