This reminds me of a question Dave LaPuma and I were knocking around the other day. How high can birds making nfc's be heard by naked ear? By microphone? Has this been worked out? Of course it is conditions-specific, so for starters how about a still night and a loudish call, like SWTH?
------------------------------------------------------------------------- Donald P. Freiday, Director of Birding Programs, New Jersey Audubon's Cape May Bird Observatory (609) 861-0700 x16 [email protected] www.bircapemay.org/blog _____ From: [email protected] [mailto:[email protected]] On Behalf Of Michael O'Brien Sent: Tuesday, April 06, 2010 4:29 PM To: Jeff Wells Cc: [email protected] Subject: Re: [nfc-l] Night flight call station results-Maine-April 1-3 Maybe the robins over your station are typically too high to be heard in the middle of the night. Just a thought. Re terns, I have also only herd Caspian. I have heard them both spring in and fall inland, but I don't recall ever hearing them along the coast. Michael ----- Original Message ----- From: "Jeff Wells" <[email protected]> To: "Michael O'Brien" <[email protected]> Cc: [email protected] Sent: Tuesday, April 6, 2010 4:08:38 PM GMT -05:00 US/Canada Eastern Subject: RE: [nfc-l] Night flight call station results-Maine-April 1-3 Very cool! Makes sense when you see large numbers of robins flying over in the early morning hours that they would be birds that have been moving at night. Funny though that over the years I don't recall picking up any within the 10 PM-2 AM window that I think of as indicating birds moving through the night as opposed to in the early morning hours when it is not as clear whether they just started migrating or are descending. Speaking of birds that move through the night but are not as readily detected, have any of you picked up terns other than Caspian Tern migrating at night? It's obvious that they migrate at night based on the way they just appear one morning in a location but it seems like you don't hear them. Though at least Caspian Terns in the fall when they have still-dependent young regularly call back and forth with the trailing young birds at night. Jeff From: Michael O'Brien [mailto:[email protected]] Sent: Tuesday, April 06, 2010 3:59 PM To: Jeff Wells Cc: [email protected] Subject: Re: [nfc-l] Night flight call station results-Maine-April 1-3 Jeff, I'm interested in your assertion that American Robin is strictly a diurnal migrant. Perhaps that is true in some areas, but in Cape May it certainly is not. We regularly see massive American Robin flights at night, in fall at least. These flights often continue or resume in the first few hours of the morning and again in the last hour or so of the day. During particularly heavy flights, the movements may continue longer into the day, but my estimation is that the bulk of the movement always takes place at night. I find their behavior to be much like that of Bobolink, only they seem to be less vocal. It would be interesting to know what others have observed and if the situation is different elsewhere. My guess is that the main difference, if any, is that robins call more frequently in certain situations and fly more quietly in others. good listening! Michael O'Brien ----- Original Message ----- From: "Jeff Wells" <[email protected]> To: [email protected] Sent: Tuesday, April 6, 2010 2:42:45 PM GMT -05:00 US/Canada Eastern Subject: [nfc-l] Night flight call station results-Maine-April 1-3 I started my automated recording station for the season here in Maine on Thursday night, April 1st. Although there were few calls each of the last three nights, the numbers increased a little each night from about 10 the night of the 1st to about 30 last night. There were a few Hermit Thrushes the first night, 6 the 2nd and 12 the night of the 3rd. There were a few Killdeer each night, a Wood Duck, and 4-10 sparrows each night with Song and White-throat plus a couple that may be American Tree Sparrow and a junco or two. A few other items of interest: -several nights had Herring Gull calls in the middle of the night that I assume are night migrating birds; -several nights had the squeal flight calls of American Robins around midnight. Although I sometimes have what I assume to be local on-the-ground robins sing and give ground alarm calls in the middle of the night, they don't give the squeal calls. The acoustics of the recorded squeal calls also seem more like birds overhead. I suspect that, as unlikely as it seems, that these were night-flying robins when by all accounts the species is only a diurnal migrant; -one night I had what sounded like a bit of song of a night-flying Hermit Thrush. I typically get some night-flying birds in May that break out in song or partial song while flying overhead but I had never picked that up for Hermit Thrush. I posted some of the call files on my blog at: www.borealbirds.org/blog Jeff Wells -- NFC-L List Info: http://www.NortheastBirding.com/NFC_WELCOME http://www.NortheastBirding.com/NFC_RULES ARCHIVES: 1) http://www.mail-archive.com/[email protected]/maillist.html 2) http://birdingonthe.net/mailinglists/NFCL.html 3) http://www.surfbirds.com/birdingmail/Group/NFC-L Please submit your observations to eBird: http://ebird.org/content/ebird/ --
