Thrushes have some of the loveliest songs among North American birds.
American Robin singing before dawn (July, ME)
The first two phrases are the typical "caroled" notes, and the next two are higher pitched "hisselly" phrases (see the sonagram). The typical American Robin sings 10-20 different carols and 75-100 different hissellys (Kroodsma). Hissellys are heard most reliably at dawn and dusk. During the day robins usually sing only caroled phrases.
This bird hidden in a conifer sang a song comprised only of hissellies (90 minutes after sunrise, Apr, PA). It was then chased off by a rival male.
Another example of a song comprised mostly of hissellies. In this case the bird was visible and sang with the bill in a slightly open but frozen position, and so it probably qualifies as a whisper song, a quiet song made without opening the beak fully. Quiet songs are often associated with aggression. (7.40am, Apr, PA).
Call notes are often interspersed between song phrases. In this example, the bird sang on the ground in darkness, then (at 60s) flew up into a tree, called for a time, and then resumed singing. There were very few hissellies in this dawn song (5.45am, Apr, PA).
Veery, at least two, possibly three birds countersinging, with calls in between song phrases (July, ME).
Hermit Thrush (July, ME)
Hermit Thrushes alternate lower with higher phrases.
The first three phrases:
Two Hermit Thrushes countersinging (July, ME).
Wood Thrush (June, NJ).
Wood Thrush singing a song variant with calls and short phrases (with Carolina Chickadee, June, NJ)
Swainson's Thrush (June, AK)
Swainson's Thrush singing an abbreviated song (June, AK)
Gray-cheeked Thrush (June, AK)
Eastern Bluebird, song 40 minutes before sunrise (June, PA). The phrases of the song at dawn often start with alarm notes.
The first four phrases:
The regular day song (Mar, PA).
Eastern Bluebird singing in fall(Oct, PA).