On Sept. 20th, I claimed a Mourning Warbler at Drake’s Beach. I thought
views were suggestive, but I identified the bird primarily by its call; it
chipped loudly and for a long time. Some birders chased the bird and took
photos, which they smartly uploaded to eBird. These photos and audio of the
bird can be found linked at the end of this email. A few reviewing the
photos noticed a few characters perhaps better for MacGillivray’s than
Mourning Warbler, and prompted a more formal review of the record. I
emailed a few experts about this sighting, and the general consensus was:
the call sounds like a Mourning Warbler, the eyering favors Mourning
Warbler, however the pattern in the throat and upper breast perhaps does
not. All noted a complete breast band and throat without any appreciable
yellow were maybe better for MacGillivray’s. Each contacted expert raised
the idea that it might be a hybrid between Mourning and MacGillivray’s
(although, obviously, no one is saying it is a hybrid). At the end of the
day, it seems this bird is not a MacGillivray’s Warbler, but there is
enough that is …odd… about it for Mourning Warbler that, as an extralimital
individual, it should be left unidentified. For those of you doing the
math, that means there have only been seven confirmed Mourning Warblers in
California this fall, not eight (wow!).
Apologies to everyone that chased this bird; this has been a good (and a
bit embarrassing) learning experience for me!
