Figure 1.
Coordination of visual display and song in a socially raised cowbird.
Song and display are coordinated in socially raised cowbirds. A spectrographic representation of a song type with 3 sound units, which are separated by silent periods (grey between the dashed vertical lines). Above the spectrogram, frames of cartoon versions of the bird's outline taken from simultaneously recorded high-speed video of the displaying bird are shown. Ranges of various defining positions of the visual display are indicated above the spectrogram (grey, horizontal lines) and the mean (black, vertical boxes).
Figure 2.
Songs of isolate cowbird before and after social exposure.
Spectrograms of songs from CB14 who was recorded in his first singing season (a, b) and re-recorded in 2010 after exposure to adult male and female cowbirds (c, d). Songs in the first year consist of atypical sound sequences (a. units 1+2+2+2; b. units 1+3), whereas after social experience the same bird sang “normal” sequences (c. 1+2+3; d. 1+2+2+3).
Figure 3.
Coordination of visual display and song in isolate cowbirds.
Isolate males sang “abnormal” songs with “normal” coordinated visual displays. Two examples with spectrograms and corresponding silhouettes of display features are shown (a. CB18 first year, 3 sound units with aberrant acoustic structure; b. CB10, third year, 1+2+2+2). The various components of the visual display are all present and appropriately positioned during song. The number of full wing movement cycles is adjusted to the number of sound units.
Figure 4.
Summary of coordination between song and visual display for songs with 4 sound units.
Temporal synchronization between components of the visual display and songs composed of 4 sound units is similar in socially raised (top) and isolate (bottom) cowbirds. To represent the temporal structure of song, the mean duration of sound units (grey box) and intervening silent periods is depicted for all song types with 4 sound units from all birds. No distinction was made in regard to which of the 3 sound units was present at what position, and, as described in the text, these units varied between socially raised and isolate birds. The time during which various components of the visual display occur relative to the temporal segments of song is shown by horizontal lines (full range of all observed occurrences). For “low” position of wing, the component that could be determined with the highest temporal precision, the mean is indicated by the vertical open box. Songs were accompanied by maximally 3 full wing movement cycles. An occasional fourth low position was quantified before closure of the wings at the end of the wing display but was not followed by an upward movement.
Figure 5.
Summary of coordination between song and visual display for songs with 3 sound units.
Songs composed of 3 sound units were also accompanied by similar displays with similar coordination. The units of sound were accompanied by maximally 2 full wing cycles. Data are displayed as described for Figure 4.
Figure 6.
Summary of coordination between song and visual display for songs with 2 sound units.
Isolate birds sang songs composed of only two sound units, but socially raised males did not sing such song types. Despite the abnormal song sequence, components of the visual display were coordinated with the shortened acoustic signal, and only one full wing movement cycle was performed. Data are displayed as described for Figure 4.
Figure 7.
Low1 placement is related to the timing of wing opening in isolates but not socially raised birds.
The relation of the beginning of the wings opening was measured relative to the onset of song (negative numbers indicate prior to song). Wing opening and Low1 position were not related in socially raised cowbirds (open circles) (regression, dashed line, R2 = 0.02, regression: F = 0.33; p = 0.57). In isolate birds Low1 occurred later with later opening of the wings (black circles, regression, solid line, R2 = 0.72, regression: F = 51.9; p = 0.0001).
Table 1.
Timing of lowest wing position within silent periods for individual song types.