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Female red-winged blackbird (Agelaius phoeniceus) vocalizations: Variation and ontogeny
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. I here examined variation among individual notes, variation in the ontogeny of individual notes, variation in the arrangement of notes, and variation in the delivery of female Red-winged Blackbird (Agelaius phoeniceus) vocalizations. A visual categorization system based on sonagrams was used to identify five categories of individual notes in this population. Notes within categories were distinguishable but grading between some note types was extensive. Structural variables used to characterize notes differed significantly among note types, but structural variables did not differ among females. The ontogeny of female Red-winged Blackbird (Agelaius phoeniceus) vocalizations was explored with 13 hand-raised females collected in California and Massachusetts. Females were divided into three treatment groups in which the social setting and the acoustic environment differed. The role of learning in the development of female vocalizations was tested by comparing individual notes among treatment groups and between hand-raised and wild MA females. Structural characteristics of notes did not differ statistically between states or among treatment groups, but note morphology did differ among treatment groups. Both the structural characteristics and morphology of some note types differed between hand-raised and wild MA females. Differences in the ontogeny of notes among groups indicated that learning may be required for the normal development of some, but not all, note types. Variation in the arrangement and delivery of notes used in female Red-winged Blackbird vocalizations was examined for correlations with the context in which the vocalizations were given. The arrangement of notes was influenced by the following contexts: the stage of the breeding season, the individual female, breeding status of the female, certain female behaviors, the presence or absence of their mate on territory, and other Red-winged Blackbird vocalizations. Variation in delivery, measured by the number of notes within a vocalization, was influenced by the stage of the breeding season, the individual female, and the breeding status of a female.
Subject Area
Zoology
Recommended Citation
Armstrong, Timothy Allen, "Female red-winged blackbird (Agelaius phoeniceus) vocalizations: Variation and ontogeny" (1994). Doctoral Dissertations Available from Proquest. AAI9420595.
https://scholarworks.umass.edu/dissertations/AAI9420595