Table 1.

Tutor regimes for four mockingbirds in this study

Tutor typeb
Bird IDSound typeaRecordingscLivecSynthesizedd
m1081 f0NOMO, WOTHNOCAFM CF
FJWOTH tone pairseCF tone pairs
2f0-SBNOMOAM
2f0-otherNOMO, WOTHFM `two-voice'
m1231 f0NOCA, BRCO, canaryNOCA
FJBRCO tone pairs
2f0-SBEATO
2f0-other
m1301 f0NOMO, NOCA, canary, WOTHNOCAFM CF
FJWOTH tone pairsCF tone pairs
2f0-SBEATOAM
2f0-otherNOMO, WOTHFM `two-voice'
m1521 f0NOMO, NOCA, canary, WOTH, WAVINOCAFM CF
FJBLJA, WOTH and HETH tone pairsCF tone pairs
2f0-SBEATOAM
2f0-otherNOMO, WOTHFM `two-voice'
  • a 1 f0, single f0 varying over time (may be pure-tonal or include upper harmonics); FJ, tutor sound contains an abrupt jump up or down in frequency; 2f0-SB, sound that contains prominent sidebands above and below a f0, visible in a narrowband spectrogram, corresponding to a second, modulating frequency (m0); 2f0-other, sounds that contain two independent fundamental frequencies, in any other combination than the sideband relationship described above (such as two-voice phenomena)

  • b `Recordings' refers to field recordings of naturally produced bird songs; playback to mockingbird juveniles during tutoring was via compact disc. `Live' tutors were birds housed in adjacent rooms, which mockingbirds may have heard. `Synthesized' tutors were computer-generated sounds, playback was via compact disc

  • c Recorded and Live tutor species, with the exception of `canary' (Waterschlager canary Serinus canarius), are listed by standard American Ornithological Union 4-letter abbreviations as follows: NOMO, northern mockingbird (Mimus polyglottos); WOTH, wood thrush (Hylocichla mustelina); NOCA, northern cardinal (Cardinalis cardinalis); BRCO, brown-headed cowbird (Molothrus ater); EATO, eastern towhee (Pipilo erythrophthalmus); WAVI, warbling vireo (Vireo gilvus); BLJA, blue jay (Cyanocitta cristata); HETH, hermit thrush (Catharus guttatus)

  • d FM, frequency modulated pure-tonal sounds; CF, constant frequency pure tones; CF `tone pairs', tones of different frequency presented in step-wise pairs; AM, amplitude modulated FM or CF tones with sidebands corresponding to the modulation frequency; FM `two-voice', two simultaneous, independent, synthesized FM sounds

  • e `Tone pairs' describes abrupt step-wise jumps in frequency; however, since the production patterns for these recorded birdsong elements are not known, do not necessarily represent frequency jumps due to non-linear dynamics