To appreciate bird song fully, it is necessary to get up really early. Not only is the amount of song greatest before sunrise, but a number of species have unique dawn songs not heard the rest of the day.
Good examples of dawn song are found among the flycatchers, which are unusual among North American birds in that they do not learn their songs.
This Acadian Flycatcher sang continuously for thirty minutes just before dawn in May along the Wissahickon Creek in Philadelphia. During each songburst it spread and quivered its tail feathers. The repeated "pi-pi-pi-pi-pi" notes before "pizza" are not heard during the day.
The Eastern Wood-Pewee adds a third phrase to its song at dawn, "ah-di-dee", the third call on the recording and the sonagram. This phrase is not usually heard during the day (June, PA).
Dawn songs are also called twilight songs, because they are often also heard at dusk. The dusk song is usually similar to the dawn song but may be different. This is the the same bird as above, singing a call-like song after sunset the previous evening. The bird countersang the same song with another bird.
A wheezy version sung just after sunrise in late September, perhaps a young bird, as fledglings have wheezy versions of the adult calls.
An example of the rarely heard flight song, 10 minutes after sunset, with squeaky notes and all three phrases. A distant bird, hence the poor quality (background noise from white-tailed deer, June, NJ).
The Western Wood-Pewee adds a second phrase in its dawn song, "tswee-tee-teet", the second call on the recording and sonagram (Jun, AK)
The Eastern Phoebe has a two-phrased dawn song, "fee-bee" and "fee-be-be". Before dawn the phrases are repeated rapidly, slowing as sunrise approaches. At first "fee-be-be" alternates with "fee-bee", but closer to sunrise "fee-bee" predominates. "Fee-be-be" is less commonly heard during the day. This recording was made thirty minutes before sunrise. (Apr, PA)
Great Crested Flycatcher dawn song, a monotonous repetition of two alternating phrases (5.00am, May, RI).
A different bird (same morning, 5.08am, May, RI)
This is a Great Crested Flycatcher singing just after sunset, with two phrases repeated over and over for about twenty minutes (May, PA)
Another, less stereotyped song at dusk. The evening song may be delivered more slowly than the dawn song (13 minutes after sunset, May, NJ).
Not all flycatchers have distinct dawn songs. For example, this is a Willow Flycatcher singing 30 minutes before sunrise. The song consists of the same three phrases heard during the day, with no difference in delivery other than the normal increased pace heard at dawn (June, PA).