Bermuda phylloscopus Warbler: Another look

and listen!

Martin Garner and David Cooper

The phylloscopus warbler found wintering on Bermuda has already attracted enormous interest. With zero phylloscopus previously recorded on the east coast of North America- what was it and where was it from?

The slightly confusing mix of characters visible in photos including active wing moult leading to some head scratching. Only Willow Warbler and Arctic Warbler are normally in active pre-breeding moult and when the calls were finally captured it was sorted- an Arctic Warbler. I think the general assumption too was that it was a Eurasian bird- of the nominate form ‘borealis’, least that was in MG’s head.

See the Original Post asking for help with ID (before sound recorded)


More images were added HERE


Then after sound recording the ID conclusion was written up HERE Bermuda Arctic Warbler the Bermuda Arctic Warbler – but which taxon and from where?


The call never sounded right. That’s to say that one of the best places to see Arctic Warbler this side of the pond in autumn is Shetland. And they always or nearly so give a single dipper-like slightly raspy call ‘dzik’. A single note. The Bermuda Warbler often/ most frequently gave a double note. I checked with Roger Riddington and Paul Harvey who have seen lots of Arctic Warblers. Invariably only uttering single notes bar one late bird 2 autumns ago which occasionally gave a double note.     XC168678-Phylloscopus Warbler Bermuda (1).png double n single Sonagram of Bermuda Arctic Warbler giving both single and double notes XC168678-Phylloscopus Warbler Bermuda (1)Sonagram of Bermuda Arctic Warbler giving typical double notes


With David Cooper, we began to compare the Bermuda bird with other ‘Arctic Warbler’ taxa. We started with the 3 way split including borealis, examinandus and xanthodryas. See the paper explaining the split. It sounded closest to examinandus, but not quite right (better heard than looking at double note sonogram.). The Bermuda bird was then compared with calls of the Alaskan form kennicotti. Bingo/ snap. At least we think so.

Have a listen look at sonograms, consider the very late extra yellow visible on the Bermuda bird.

Listen to: Kamchatka Leaf Warbler examinandus, Arctic Warbler borealis and Japanese Leaf Warbler xanthodryas  >>> HERE <<< 

Listen to: Alaskan kennicotti >>> HERE <<<

Listen to: the Bermuda Arctic warbler >>> HERE <<<

Oh and if kennicotti can reach Bermuda– a shorter distance, great circle route could take kennicotti to… Shetland, or the Outer Hebrides or pretty much anywhere in Britain. #just saying.


Williamson (1962) states ‘P. borealis is a variable species, and the only forms which show any degree of constancy are kennicotti and xanthodryas, and these are valid on bill-structure as much as colouration.
P. borealis kennicotti
This race is similar to borealis, though perhaps yellower below. It has a weak bill more like that of Greenish. Vaurie gives the following measurements: wing 62-69, bill 12.5-14.5; first-winter birds are often smaller.
Maybe that’s why some plumped for Greenish Warbler?

Alaskan kennicotti and taxonomy?

One might further ask the question whether the taxonomy of Kennicott’s Warbler..kennicotti needs a re-appraisal…

Bermuda Phyllosc-DSC_9675 The Bermuda Arctic Warbler– best fit kennicotti...   XC140995-Arctic Warbler2013-6-9-3 kennicotti 2 kennicotti Arctic Warbler XC140993-Arctic Warbler2013-6-9-1 kennicotti 4 kennicotti Arctic Warbler. Sonagram and sound virtually identical to Bermuda phyllosc. XC140994-Arctic Warbler2013-6-9-2 kennni 94kennicotti Arctic Warbler- some recordings contain single notes too


Akihiro Sakuma from Japan kindly commented as follows::

Oh! It’s very difficult to identify what ‘ Arctic Warbler ‘.
But for me  it seems to be ‘kennicotti ‘.

‘borealis‘ upperparts  are more dark green colour and underparts dusky
without yellowish, and also some streaks on its breast.
But this ‘Arctic Warbler’ s underparts yellowish and without streaks on its

‘examinudus’ also has yellowish underparts but is not smart proportion like
this ‘Arctic Warbler’
And this ‘Arctic Warbler’ call is not like ‘examinandus’ ( Kamchatka Leaf

So I think this  Arctic Warbler ‘ is  ‘kennicotti ‘,  and  as  its
underparts and supercilium are yellowish, it seems to be 1st winter .

Bermuda Phyllosc-DSC_9691

2 thoughts on “Bermuda phylloscopus Warbler: Another look

  1. Michael

    The photo caption reading “the Bermuda Arctic Warbler – but which taxa and from where?” should read “…which taxon…”. Taxon is singular; taxa is plural. It cannot be more than one taxon.

    1. Martin Garner Post author

      Thanks Michael- quick blog posting and no proof reading is to blame- otherwise I was aware of what you say but thanks for pointing out and sharpening up the post


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