Most of us would know our mother's voice on the phone from the first syllable uttered. A recent Cornell study suggests that crows also can recognize the voices of their relatives.
By recording and analyzing the alarm caws of American crows, Jessica Yorzinski '05 found seven subtle acoustic differences in features that differed among individuals -- differences that the crows could potentially use to recognize one another's calls. She also found that female crows had higher-pitched calls than males. Yorzinski is now a graduate student at the University of California-Davis studying the mating choices of peacocks.
The recently published study suggests that this ability could be particularly important for crows because they interact with family members throughout their lives.
"Lots of crows end up breeding in the neighborhood they grew up in so there is no doubt in my mind that they recognize each other. How they do that, we have no idea," said co-author Kevin McGowan, a researcher and editor at the Cornell Lab of Ornithology who has studied the family lives of crows for 18 years.
To see if vocalizations might be a cue, Yorzinski recorded more than 10,000 alarm calls (made when she approached the birds) of 15 crows from five family groups around Ithaca that had been individually marked with tags as part of a long-term study co-authored by McGowan. She then measured more than two dozen acoustic features of a subset of these calls, including frequency, duration, bandwidth and energy distribution using a sound analysis program developed by the Lab of Ornithology's Bioacoustics Research Program.
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