Hi, all. I'm wondering if anybody has opinions, or even facts, regarding a flight call I recorded during nautical dawn on Saturday, Nov. 2nd, 2013 over Greenlee Preserve, eastern Boulder County, Colorado, USA.
I recorded the flight call three times, and I'm assuming that the three calls came from the same bird, and that it was overhead. As you'll see (and hear), the flight calls are faint. But I think there's enough spectrographically for analysis. The second call (presented here first) was the loudest, and it caught my attention. I don't recall hearing the first flight call, and I heard the third flight call only faintly. Here's what I'm seeing on the spectrograms: All three are high-pitched (ca. 8 kHz), double-banded (upper band stronger than lower), fairly pure-tone (i.e., little modulation), slightly descending throughout, and on average 108 milliseconds in duration (n=98, n=106, n=121 for the three flight calls). The entire calling sequence is too long for me to send to the list. (I tried earlier, and the post bounced.) So these three clips are pretty short. The low-frequency noise is the din of traffic; I was recording near a busy road at a place where a lake and a marsh abut. Thanks in advance for any thoughts on this one. Ted Floyd Lafayette, Boulder County, Colorado, USA -- NFC-L List Info: http://www.NortheastBirding.com/NFC_WELCOME http://www.NortheastBirding.com/NFC_RULES http://www.NortheastBirding.com/NFC-L_SubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nfc-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NFC-L 3) http://birdingonthe.net/mailinglists/NFCL.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
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