eWestern BirdsThe Quarterly Journal of Western Field Ornithologists
Vol. 41, No. 1
Western Field Ornithologists
A Reassessment of Homologies in the Vocal Repertoires of Phoebes
Archibald McCallum and Nathan D. Pieplow
ABSTRACT: During the breeding season, phoebes (Sayornis) sing vigorously at dawn with two or three highly stereotyped, probably innate, song types. All song types are combinations of a species-specific introductory note and a terminal phrase. Building on a classic assessment of repertoire structure by W. J. Smith, we recognize three phrase types for the genus (I, II, and III), all of which are used by Say’s Phoebe (S. saya) but only two of which (I and II) are used by the Black (S. nigricans) and another two of which (II and III) are used by the Eastern (S. phoebe) Phoebe. A recently discovered hybrid male Black × Eastern used all three phrase types and sang like Say’s Phoebe by embedding single type II and III songs in longer strings of type I songs. Thus, what appears to be the primitive sequencing of song types was potentiated through reconstitution of the complete repertoire via hybridization. For future studies, we recommend replacement of Smith’s terminology with a simpler scheme recognizing three homologous song types.