Listening to a Continent Sing

A Swainson's thrush awakes not with songs but with calls. How many different ones he has no one seems to know, but at least three matters are clear.

First, one call can grade into another, perhaps creating infinite variations; listen to the sequence from 0:17 to 0:26 and you feel this transition.

Second, a given call can vary from one rendition to the next; from 0:26 to 1:28, hear how the duration of that particular call varies.

Third, these thrushes talk to each other with these calls, often matching each other's calls, responding in some way to each other's vocal efforts. Listen from 0:50 to 1:27 and you hear how the foreground and background birds (both males?) match each other with that ringing, tonal note, and how at 1:29-1:32 both birds switch to another call, again matching each other.

Background

Pacific-slope flycatcher, another Swainson's thrush (singing and calling).

Photo by John Van de Graaff