On Saturday night, there was a cleanup flight following Friday’s awesome night 
migration. Among the scattering of calls throughout the night, I recorded a 
total of 10 possible Bicknell’s Thrush night flight calls. Each of the calls 
peaked above 4.0 kHz with the highest two calls peaking around 4.8 kHz. While 
none are “clear” Bicknell’s Thrush calls (peaking above 5 kHz), the structure 
of the calls (sharp onset followed by a variably modulated and notably longer 
trailing descent) are very reminiscent of Bicknell’s Thrush call examples which 
are noted in the Evans and O'Brien Flight Calls of Migratory Birds CD-ROM.

Overnight Saturday to Sunday morning, there was a notably Eastern component to 
the winds over Etna, NY. This could potentially account for an Eastward shift 
of birds departing from their mountaintop breeding grounds in the Adirondacks.

While I realize these could arguably be particularly high frequency calls from 
Gray-cheeked Thrushes, it would likewise seem reasonable that these could be 
lower frequency Bicknell’s Thrushes. So much is yet to be learned about sexual- 
and age-related differences in calling frequencies of these two species.

Attached are the first five calls, with the remaining five appearing in a 
separate message to the NFC-L eList.

I welcome any feedback, and good night listening!

Chris T-H

Christopher T. Tessaglia-Hymes
Field Applications Engineer
Bioacoustics Research Program, Cornell Lab of Ornithology
159 Sapsucker Woods Road, Ithaca, New York 14850
W: 607-254-2418<tel:607-254-2418>   M: 607-351-5740<tel:607-351-5740>   F: 


NFC-L List Info:

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:


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