Structure and organization of songs of south-temperate Grass Wrens (Cistothorus platensis)

PAULA S. GARRIDO; DREW RENDALL; ROSARIO PANISITI; NATALIA GARCÍA; LLAMBIAS PE

JOURNAL OF FIELD ORNITHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2021

0273-8570

Studies of geographic variation in bird song can provide importantinsights into vocal evolution. An intraspecific approach, focused on a single specieswith a broad distribution, can be particularly helpful in understanding the diverseselective pressures on the characteristics of songs and singing behavior. Grass Wrens(Cistothorus platensis) are one such species, inhabiting tropical and temperategrasslands across the Neotropics. We studied Grass Wrens in Mendoza, Argentina, todetermine the structure, organization, and delivery of their songs, song repertoire sizes,and patterns of song sharing among males in a resident, mainland south-temperatepopulation. Over two breeding seasons, we recorded and analyzed 27,795 songs from29 color-banded males. Songs of male Grass Wrens contained a few, low-volumeintroductory notes typically followed by one, but sometimes more, syllable typesrepeated as a trill. Males often repeated a sequence of two or three different song types(A-B-C, A-B-C, ?) several times before switching to a different sequence (D-E-F).Syllable and song type sharing was high among males. The size of recorded syllable andsong type repertoires of individual males varied with sampling effort. The introductionof new syllable or song types by males slowed, but did not reach asymptotes, withincreasingly large samples of recordings. Many of these patterns are consistent withprevious reports for Grass Wrens and other Cistothorus wrens, possibly representingcore features of song design in this species group. Our results concerning song sharingamong males in a resident population are also consistent with a previous proposedrelationship between male song sharing and breeding-site fidelity. In the latter respect,Grass Wrens of Central and South America are more similar to Marsh Wrens thanSedge Wrens of North America, providing support for a recent proposed split betweenGrass Wrens and Sedge Wrens formerly considered conspecific.