Andrew Farnsworth
Fri, 18 Dec 2009 15:04:16 -0800
Hi all, Ah, the interesting directions to pursue! Great thoughts, Gerard, Magnus, and Ross! Two thoughts/observations: - first, Rose-breasted Grosbeaks produce calls that vary by age, and it's likely that other species might as well. For grosbeaks, these seem to coincide with discrete call types that differ rather noticeably (by spectrogram and by ear) from one another in duration, frequency, and note structure between juveniles and adults (in diurnal and nocturnal migration) . . . - second, during my dissertation research and in collaboration with Mike, Emma, Lewis, and the Powdermill Avian Research Center folks, I found that there were subtle but statistically significant differences in various call measurements by age and sex in some species of Parulid warblers; these data come from recordings of captive birds (a la Lanzone et al. 2009 in the July issue of Auk), so whether this has practical or biological relevance or application remains to be seen (we're talking potentially highly esoteric subtlety in the machine learning/statistical sense rather than subtle but clearly audible difference typical of some species' complexes to trained field observers). I suspect that this subtlety, no matter how you describe it, would be mostly lost in the typical types of recordings that we make of passing, vocal nocturnal migrants - so, I won't be the one to shoot down Magnus!!! Regardless, I hope to publish this warbler work at some point in 2010 or 2011, but I can make available the chapter to those interested. . . Best, Andrew On Fri, Dec 18, 2009 at 11:23 AM, SLIMBIRD Gerard <gphill...@istar.ca> wrote: > A related discussion which I’m sure many on the list might be interested in > learning more about in general is flight call variation of adult verses > juvenile birds. Any known examples of North American species that give > distinctive age related flight calls either diurnal or nocturnal? > > Sincerely, > Gerard Phillips > Ontario, Canada > > On 12/17/09 10:48 AM, "Andrew Farnsworth" <andrew.farnswo...@gmail.com> > wrote: > > variation may exist among calls given in migration, non-breeding, and > post-breeding seasons, and on and on > > It’s bordering on pure speculation and is only just relevant to this group, but I have a sneaky suspicion the alarm calls of Blackbird are sexually dimorphic. I’m collecting recordings at the moment to find out. Cheers Ross Ahmed From: bounce-4786788-10116...@list.cornell.edu [mailto:bounce-4786788-10116...@list.cornell.edu] On Behalf Of Magnus Robb Sent: 18 December 2009 17:04 To: nfc-l@cornell.edu Call ListServe Cc: Andrew Farnsworth; SLIMBIRD Gerard Subject: [nfc-l] passerines with sexually dimorphic flight calls? - Hide quoted text - Equally interesting is the question of which passerines (and 'near-passerines') can be sexed according to their flight calls outside of the breeding season. I have not searched for examples in any thorough way, although I have been recording migrants and noting sex when possible for a long time, without noticing examples. During spring migration, some birds may sing while passing overhead, and depending on the species, this might be limited to males. Limiting the discussion to flight calls, however, I can only think of Raven as a passerine known to have at least some male- or female-only calls throughout the year. There are many more examples among non-passerines, eg Apus swifts, but most passerines seem to share non-breeding call repertoire across the sexes without noticeable differences. I would be delighted to be shot down and shown that there are many examples, but what are they? Alternatively, are there instances of some passerine species where males use certain shared calls much more often than females outside the breeding season? all the best, Magnus Robb -- NFC-L List Info: http://www.NortheastBirding.com/NFC_WELCOME http://www.NortheastBirding.com/NFC_RULES Archives: 1) http://www.mail-archive.com/nfc-l@cornell.edu/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/ --