Colony and population dialects in yellow-rumped caciques (Cacicus c. cela) and red-rumped caciques (Cacicus h. haemorrhous)
Résumé
The yellow-rumped cacique (Cacicus cela cela), a colonial polygynous Icterid widespread in
South America, is a model of reference for demonstrating colony dialects in songbirds, as
shown by Feekes (1977, 1982) on the ‘short song’ (‘Cela-song’) in this species. Further
studies, e.g. in European starling (Hausberger, 1986), showed the presence of individual
signature and dialects at different spatial scales (local and regional). This work presents our
field study of the vocal repertoire of C. c. cela and Cacicus haemorrhous haemorrhous in
French Guyanian metapopulations. One to three males per colony were followed by eye
during a one-period observation and their vocalizations digitally recorded. Instead of the
traditional visual categorization of songs on sonagrams, we used a series of objective and
reproducible measures of frequencies and timing. Results showed vocal sharing of the short
song at colony level in C. c. cela and at local level in C. h. haemorrhous. These results agree
with those found by Trainer (1989) on another subspecies: C. cela vitellinus in Panama.
While Feekes (1977, 1982) proposed that song sharing at colony level could work has a
group-closing process in C. c. cela (the ‘password hypothesis’), our observations rather
suggest song imitation in socially open groups.