Thanks to some persistence from Wendy Frith, who finally got some audio recordings, it appears that the identification of the Phylloscopus warbler on Bermuda has been nailed down: Arctic Warbler. Andrew Dobson has photos and audio links in his eBird checklist, which also gives a nice sense of the other birds at the site. Obviously some defended this identification at the outset. With the benefit of hindsight, please do add your comments to how this might have been identified if the audio recordings had not been obtained.
For those that use eBird for record keeping worldwide, please note how photos, audio recordings, and field notes can be combined on a checklist like this, which also contributes to your personal record keeping and global database. For example, here is the ever growing range map for Arctic Warbler. Your additional records will help to make this map (and others) even more complete.
This is a new record for Bermuda and the first record for Arctic Warbler on the North American side of the Atlantic Basin. If anything, this record has been instructive (for us North Americans anyway!) as to just how difficult some Phylloscopus can be and just how important the calls are to confirming the identification. Congratulations to our Bermuda colleagues who stuck with this one and finally nailed it!
Here is one of Andrew’s more recent photos, but do be sure to check out the full set.