Several warbler species sing two different types of song, known as accented and unaccented. Accented songs are sung to attract females, unaccented songs are considered to have a more aggressive function and are used to maintain territory. Accented songs are sung all day until the male is paired up, and then singing drops off significantly. Unaccented songs are the predominant songs given at dawn and dusk.
In "The Singing Life of Birds" by Don Kroodsma he writes that the male Chestnut-sided Warbler learns accented songs (there are 4-5) in the first year of life, probably in migration. These songs are the same throughout the species' range. The unaccented song is not learnt until the young male arrives on his breeding grounds, and is learnt from neighboring males. Each male learns up to 12 unaccented songs. Each local group of Chestnut-sided Warblers has a different set of unaccented songs, so that throughout the species' range the number of variations is innumerable.
Chestnut-sided Warbler, accented song (July, ME)
unaccented song (July, ME)
A bird singing accented then unaccented songs (July, ME).
The American Redstart has a repertoire of 1-4 accented and 2-10 unaccented songs (up to 12 total). Accented songs end in a chevron on the sonagram. Individual accented songs tend to be repeated over and over (repeat mode) whereas the unaccented are often sung in variable sequences (serial mode).
accented in repeat mode(May, NJ)
unaccented in serial mode, actually two phrases alternating (July, ME)
Songs in serial mode (May, NJ).
Unaccented songs can sound similar to Black-and-white Warbler or other high-pitched species but are shorter (July, ME).
American Redstart and Chestnut-sided warbler singing together (May, NJ).
According to BNA, Yellow Warblers have a repertoire of about 15 songs, which may be accented or unaccented, but it is the mode of singing that defines song classification, independent of whether or not the song is accented, with more immediate variety at dawn, and repeat mode predominating during the day.
This bird was recorded at dawn (May, NJ).
phrases 1 and 2
Note the similarity to Chestnut-sided
phrases 7 and 8
Each Hooded Warbler sings one accented but several non-accented songs.
accented (May, NJ)
unaccented (before sunrise, June, NJ)
Magnolia Warbler accented songs can sound very similar to Hooded Warbler (migrant, May, PA).
accented (July, ME)
Magnolia Warbler unaccented songs can sound similar to Chestnut-sided, but are generally shorter (July, ME).
Prairie Warblers sing several versions of two song types, called A and B, which are equivalent to accented and unaccented respectively.
Type A is a rising series of buzzy notes (June, NJ).
Type B begins with clear notes (June, NJ).
Several warbler species sing only one version of each of the two song types:
Black-throated Green Warbler.
accented song (July, ME)
unaccented (July, ME)
Occasionally a bird of one species will sing the song of another species. This Black-throated Green Warbler sang a normal accented song but the unaccented song was preceded by a Pine Warbler-like trill. This bird returned to the same spot for three successive years, and interestingly, the habitat was typical for Pine Warbler, dry oak/pine woodland, but not for Black-throated Warbler; this species breeds only in white cedar bogs in the pine barrens in southern New Jersey (May, NJ).
normal unaccented song by this bird
Type A or accented, a simple rising buzz with an end note (migrant, May, NJ)
Another version of the song has a falling trill at the end. Presumably this is an accented song as the bird switches to an unaccented song at 68s (July, ME).
Type B or unaccented, more complex with clear and buzzy notes (July, ME)
A clearer-toned version (May, PA).
The Black-throated Blue Warbler is another species that has two different song types. The so-called Type 1 song has several relatively pure-toned notes in the beginning. The Type 2 song usually has less notes, all buzzy. It is likely one is used for maintaining territory, and the other for attracting females, but not a lot of study has been done on this species.
Type 1 (July, ME, juvs in background)
Type 2 (July, ME)
accented (June, NJ)
Blue-winged Warbler (with Common Yellowthroat)
accented (May, NJ)
Tennessee Warblers sing either a 2-parted or a 3-parted song, the different song-types are of unknown significance.
3-parted(migrant, May, ND)
Another 3-parted song (migrant, May, ND)
Nashville Warblers sing a faster song at dawn that may function as an unaccented song. The regular slower version of the song is sung during the day and in interactions with females (BNA).
regular song (July, ME)
Pine Warblers have a repertoire of more than one song and some songs are faster than others.
rapid song (June, NJ)
Pine Warbler singing 15 minutes before sunrise, running through an apparent repertoire of four songs (June, NJ). Incidentally, this is a good way to distinguish a singing Pine Warbler from the similar Chipping Sparrow and Worm-eating Warbler, as those birds sing only one song.
Pine Warblers and Chipping Sparrow (at 10,34,44 and 56s) singing together (May, NJ).
Yellow-rumped Warblers have a variety of song phrases, as shown by these migrants singing in serial mode ie different consecutive phrases. The loose trills tend to fade at the end. Some phrases can sound similar to Chestnut-sided unaccented songs.
(Northern Rough-winged Swallow at 34s, May, PA)
(breeding grounds, July, ME)
Each Canada Warbler sings about 11 different songs, often given in serial mode. A flight song has also been described. Canadas generally sing in the forest understorey.
(migrant, May, NJ)
The Yellow-breasted Chat has a highly variable song including mimicry, in this case crow calls (June, NJ)