I've termed flock calls those calls that are made between birds as they forage (that are not flight or aggressive calls). Chase and other agonistic calls are calls between two or more birds, involving chasing or other apparently aggressive behavior.
Dark-eyed Junco, a flock of about 60 birds at Whitesbogs, NJ in November. The predominant call is the tu-tu flock call, other calls are the buzzy flight call, one bird singing at 6s and a titter call at 10s.
buzzy flight calls and twitter call (above tu-tu calls)
Another example of the tu-tu calls with a series of rapid chips at the end of the recording (Dec, PA).
Several birds vocalizing, with series of chuk-like notes (at 17s) and more examples of the twitter (Apr, PA).
Flock calls of White-throated Sparrows include chip calls and "laughing" calls (Oct, NJ).
laughing calls (Dec, PA)
Laughing calls by White-crowned Sparrows (Feb, NV).
Similar call by a Harris's Sparrow, a related species that is only a rare vagrant to the east (Mar, NE).
When White-throated Sparrows interact closely, they chip rapidly. So it appears that the chip call is used for flock communication, aggressive interaction and as an alarm call.
Two birds rising in the air in a brief aggressive encounter at 4s, with flight calls (Dec, NJ).
American Tree Sparrows are also very vocal in winter. This is their common call, a unique "chu-wit".
single bird (Jan, PA)
flock (Jan, PA)
single bird (Dec, PA)
flock (Dec, PA)
Note the variety in these calls.
These are also termed growls.
Savannah Sparrow (Oct, PA).
Swamp Sparrow interaction calls are lower, and like Savannah and Chipping Sparrow growls, commonly heard (Oct, NJ)
chips followed by growls (at dusk, Nov, PA)
Chipping Sparrow, chase calls between birds in a flock of about twenty (Nov, PA).
American Tree Sparrow growl (Jan, PA).
The Song Sparrow growl rises and is similar to that of the Swamp Sparrow but appears to be variable; immatures interacting (Aug, PA).
Two (probably young) birds chasing each other with lower growls (July, PA).
Two adult Song Sparrows in close interaction, both singing and making high chip calls, then growling by one as the other sang (Tree Swallow at 2s, Apr, PA).
Song Sparrow excited chip series, presumed interaction between two birds (dusk, Nov, PA).
the full series, reduced time scale
Other agonistic calls
This low grating call was made by a Song Sparrow while feeding with White-throated Sparrows and Dark-eyed Juncos, and appeared to be an aggressive vocalization. It was not made when the bird was feeding alone (Dec, PA).
This call was made during an aggressive interaction between a White-throated and Song Sparrow, where the Song Sparrow was the aggressor (identity of calling bird unknown,Jan, PA).
Interaction calls between an Eastern Towhee (male) and Spotted Towhee (female) where the Eastern Towhee was the aggressor. One bird is uttering a series of chips, followed by two buzzy calls from the other bird. The series of chips has been described in the literature as a fear or flee call and is made by both species (Dec, Palmyra, NJ).
Song Sparrow chitter call, a soliciting call made by females in spring (Apr, PA).
Chipping Sparrow calls while mating, a rapid series of chips at 8 and 21s (May, DE).
Twittering by a pair of Field Sparrows (May, DE).
Eastern Towhee female whinny call, described as a precopulatory call during nest-building by BNA. This was a bird foraging under vegetation with a male perched nearby (Apr, PA).
Chips and trills (calls above 6kHz) by male Field Sparrow before dawn (May, DE).
Male twittering and chipping at dawn (Oct, PA).
The above was most likely an immature male as it sang a few phrases of plastic song.