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 On 18 Dec 2009, at 16:2324, SLIMBIRD Gerard 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 > -- 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/ --
