Patterns of Vocalization Use by Female Red‐winged Blackbirds (Aves: Emberizidae, Icterinae): Variation and Context

Abstract

Variation within communication systems can be examined at several levels: variation among individual notes, variation in the arrangement of notes, and variation in delivery. Here, variation in the arrangement and delivery of notes used in female red‐winged‐blackbird vocalizations is described, and this variation is examined for correlations with the context in which the vocalizations were given. Within a vocalization, notes were normally arranged in a series of similar notes. Of the 75 different note arrangements recorded from the population, 12 arrangements accounted for 84 % of vocalizations. Provisional results indicate that the arrangement of notes was influence by the following contexts: 1. The stage of the breeding season; 2. The individual female; 3. The breeding status of the female; 4. Certain female behaviour patterns; 5. Other red‐winged‐blackbird vocalizations; and 6. The presence or absence of a female's mate in the territory. Variation in delivery was measured by the number of notes within a vocalization; delivery was influenced by the stage of the breeding season, the individual female, and the breeding status of a female. Most note arrangements were used in a wide variety of contexts and did not appear to be functionally distinct.