Hi Paul and all, Given that growth (or fault) bars and their interpretation are probably unfamiliar to many readers, this bird offers a learning opportunity. If a bird experiences nutritional or other stress while its flight feathers are actively growing, faint bars (thin bands of weaker feather structure perpendicular to the shafts) appear on the growing feathers at positions associated with each feather's stage of growth when the stress occurred. These are often visible on the fully grown wings and tail of a bird, and their alignment or lack of alignment is often indicative of age: adult passerines obviously can't shed and replace all their wing feathers at once (though it's not unusual for adults to lose their tail feathers simultaneously), so they replace their wing feathers in sequence, often just prior to southbound migration. Thus, the growth bars of adults of these species are not aligned, falling instead in different positions based on how well grown each feather was when the stress(es) occurred. Conversely, juvenile birds grow their first set of flight feathers simultaneously, resulting in alignment of growth bars, if present.
The Queens Yellow-headed Blackbird is an adult, based on its almost entirely white primary coverts. Thus, it would not show aligned growth bars (which were posited as possible points of weakness for the damaged feathers on this individual). The question of how this bird's plumage came to such a state intrigues me. It's difficult for me to imagine people keeping this species, which sounds basically like a chainsaw, as a cage bird, but I've been told never to underestimate people's capacity for treating animals unreasonably. On the other hand, these dates are exactly when this species is expected in the East as one of our most regular long-distance passerine vagrants. I wonder whether rather than "captivity" per se, this bird somehow got into something like a greenhouse, chicken coop, or other confinement that resulted in the feather damage. Shai Mitra Bay Shore ________________________________________ From: bounce-124977092-3714...@list.cornell.edu [bounce-124977092-3714...@list.cornell.edu] on behalf of Paul R Sweet [sw...@amnh.org] Sent: Friday, September 25, 2020 8:50 AM To: nysbirds-l@cornell.edu Subject: [nysbirds-l] Queens Yellow-headed Blackbird Thanks as always for the excellent post Tom. One thing that I have not seen mentioned on this forum is that the Flushing Meadows Yellow-headed Blackbird has clearly spent time in captivity. The clean cuts to the flight feathers and the cage wear on the tail are classic indicators of a caged bird. I’ve heard some mention on other forums of fault bars, this is not what we are seeing. Gabriel Willow has some flight shots on his ebird list that show this well https://ebird.org/checklist/S73707073 Good birding, Paul Paul Sweet Collection Manager Department of Ornithology American Museum of Natural History Central Park West at 79th Street New York, NY 10024 -- NYSbirds-L List Info: Welcome and Basics<http://www.northeastbirding.com/NYSbirdsWELCOME.htm> Rules and Information<http://www.northeastbirding.com/NYSbirdsRULES.htm> Subscribe, Configuration and Leave<http://www.northeastbirding.com/NYSbirdsSubscribeConfigurationLeave.htm> Archives: The Mail Archive<http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html> Surfbirds<http://www.surfbirds.com/birdingmail/Group/NYSBirds-L> ABA<http://birding.aba.org/maillist/NY01> Please submit your observations to eBird<http://ebird.org/content/ebird/>! -- -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME.htm http://www.NortheastBirding.com/NYSbirdsRULES.htm http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birding.aba.org/maillist/NY01 Please submit your observations to eBird: http://ebird.org/content/ebird/ --
