Can Nocturnal Flight Calls of the Migrating Songbird, American Redstart, Encode Sexual Dimorphism and Individual Identity?
Bird species often use flight calls to engage in social behavior, for instance maintain group cohesion and to signal individual identity, kin or social associations, or breeding status of the caller. Additional uses also exist, in particular among migrating songbirds for communication during nocturnal migration. However, our understanding of the information that these vocalizations convey is incomplete, especially in nocturnal scenarios. To examine whether information about signaler traits could be encoded in flight calls we quantified several acoustic characteristics from calls of a nocturnally migrating songbird, the American Redstart. We recorded calls from temporarily captured wild specimens during mist-netting at the Powdermill Avian Research Center in Rector, PA. We measured call similarity among and within individuals, genders, and age groups. Calls from the same individual were significantly more similar to one another than to the calls of other individuals, and calls were significantly more similar among individuals of the same sex than between sexes. Flight calls from hatching-year and after hatching-year individuals were not significantly different. Our results suggest that American Redstart flight calls may carry identifiers of gender and individual identity. To our knowledge, this is the first evidence of individuality or sexual dimorphism in the flight calls of a migratory songbird. Furthermore, our results suggest that flight calls may have more explicit functions beyond simple group contact and cohesion. Nocturnal migration may require coordination among numerous individuals, and the use of flight calls to transmit information among intra- and conspecifics could be advantageous. Applying approaches that account for such individual and gender information may enable more advanced research using acoustic monitoring.
Bioacoustic Research Program, Cornell Laboratory of Ornithology, Cornell University, Ithaca, New York, United States of America.
Emily T
http://orcid.org/0000-0002-0781-6091
ET
Griffiths
Bioacoustic Research Program, Cornell Laboratory of Ornithology, Cornell University, Ithaca, New York, United States of America.
Sara C
SC
Keen
Powdermill Avian Research Center, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, United States of America.
Michael
M
Lanzone
Information Science, Cornell Laboratory of Ornithology, Cornell University, Ithaca, New York, United States of America.
Andrew
A
Farnsworth
D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D005260:Female; D005426:Flight, Animal / Q000502:physiology*; D007206:Individuality; D008297:Male; D012727:Sex Characteristics; D020308:Songbirds / Q000502:physiology*; D014828:Vocalization, Animal / Q000502:physiology*