Figure 1.
Spectrograms of crows produced by Japanese quail and European quail.
A: Japanese crow; B and C: European wawa; D: European triplet. The wawa is composed of 2 (B, 87%), rarely 3 (C, 13%) syllables [39]. TD: Total Duration; S1, S2, S3: duration of Segment 1, 2, 3; T12: time interval between impulsion 1 and impulsion 2; T23: time interval between impulsion 2 and impulsion 3. Between brackets: number of syllables per segment for each motif. Below: coding of syntactical organization of the motif. S: syllable, 0: silence.
Figure 2.
Structural organization of crows produced by hybrid quails.
Hybrid crows that resemble the ones produced by the two parental species are squared. Arrows indicate transitions between the different crows. These transitions could be described using mechanisms observed during vocal ontogeny of crow [45] namely Silence Insertion (SI) and Modification of the Spectral Components (MSC). A third mechanism, Segment deletion (SD) is sometimes observed in Japanese quail (second syllable is sometimes omitted). S1 to S3: segment 1 to segment 3. Left bottom corner of each spectrogram: coding of syntactical organization of the motif. S: syllable, 0: silence. See text for details.
Figure 3.
Characteristics of crowing activity in quails.
A. Number of crows emitted per bout (mean±SE). B. Intra-individual similarity of acoustic structure in hybrid crows. Like European quails, some hybrid quails produce two different motifs. Number below the graph (n1/n2): n1: number of quails producing two different motifs; n2: total number of quails. ***: p<0.001. EUR: European quail; JAP: Japanese quail; H1: female japonica × male coturnix; H2: female coturnix × male japonica; F2: female H1× male H1; BC1: female H1× male coturnix; BC2: female coturnix × male H1.
Table 1.
The different types of syntactical organization exhibited by the hybrid quails.
Table 2.
Mean values (±SEM) for all acoustic variables. Kruskal Wallis results for differences between groups.
Figure 4.
Discriminant function analyses applied to the acoustic parameters of crows.
A. Calls produced by the European quail, the Japanese quail and backcrosses. B. Calls produced by the European quail, the Japanese quail and hybrids of second generation. C. Calls produced by the European quail, the Japanese quail and hybrids of first generation. H1: female japonica × male coturnix; H2: female coturnix × male japonica; F2: female H1× male H1; BC1: female H1× male coturnix; BC2: female coturnix × male H1; EUR1: wawa of the European quail; EUR2: triplet of the European quail; JAP: japonica.
Table 3.
Pooled within-groups correlations between discriminating variables and standardized canonical discriminant functions.
Figure 5.
Spectrograms of hybrid crows, illustrating the intra-individual variability.
A1 to A6: developmental stages of crows produce by one quail. A1: crow with a structure similar to the wawa produced by the European quail. A2 to A4: crows produced later during the recording session. A5 and A6: the two stable forms produced by the quail few days later. B1 to B6: developmental stages of crows produced by another quail. This quail always produced bouts with 2 successive crows. B1 and B2: crows produced at the beginning of the recording session. Note the similarities between the two motifs. B3 and B4: intermediary stage. Note the emerging differences between the 2 crows, and the differences between B2 and B4 (second crow of the bout). B5 and B6: stable motifs produced by this quail, produced about 30 minutes after the recording session started.
Figure 6.
Spectrograms of hybrid crows, illustrating the intra-individual variability observed from one year to the other.
A1 and A2: crows produced by one quail the first year. A3 and A4: crows produced by the same quail the second year. A1 and A3 are structurally similar; A4 constitutes a new syntactical form. B1 to B3: crows produced by a second quail. B1: single motif produced by this quail the first year. B2 and B3: crows produced by this quail during the second year. B1 and B3 are structurally similar. C1 to C5: crows produced by a third quail. C1 and C2: crows produced during the first year. C3 to C5: crows produced by the same quail the second year. C3 is structurally similar to C1; this is also the case for C2 and C5 despite that the intersyllabic gaps changed dramatically from one year to the other. Structure of the crow C4 is intermediary between C3 and C5. This accidental form occurred only once during the recording session, and could constitute an ‘accidental’ form.