Following from this post HERE, a paper published in the 2015 edition of Irish Birds shows how the first record of a Chiffchaff of the race abietinus was genetically identified at Killarney (along with six Siberian race birds, tristis).
The authors, B.O'Mahony, D.Farrar and M.Collinson, have made the Irish Birds article available to download from this link HERE. Mercifully, for a genetics-based ornithological paper, it is short and accessible.
From a birders perspective, perhaps the most striking finding was the consistent genetic differences between tristis and the other two races, abietinus (the Scandinavian race) and colybita (the common breeding race of Chiffchaffs in Ireland). Many birders would argue that the field characters of the increasing number of tristis Chiffchaffs in Kerry and Ireland in autumn and winter are readily discernible, such birds often easily identifiable from our more regular colybita Chiffchaffs.
The genetic distinction found in this paper will surely fuel the argument that tristis Chiffchaffs should be 'split' to become a full species in its own right, Siberian Chiffchaff.
It must now be close to the time to get your out your best clicky pen, get comfy in your most comfy of armchairs, and get ready to give yourself a tick. Welcome to the list, Siberian Chiffchaff.
The best clicky pen – BIC 4-Color™ Retractable Ballpoint Pen, Medium Point 1.0mm, Blue Barrel. Black, blue, red and green inks all in one pen. For armchair ticks, red is recommended.
As for identifying abietinus Chiffchaff? The bird trapped at Killarney was only identified as such from the genetic study. Such a bird looked identical to colybita Chiffchaffs in the hand and this individual at least would not have been identifiable as anything other than colybita in the field (though no calls from this individual were heard).
Chiffchaff of the race colybita – a typical 'Irish'-type bird, richly suffused with olive and buff tones, Ross Castle, February 2015 (D.Farrar/B.O'Mahony).
Chiffchaff of the race tristis – a Siberian Chiffchaff, pale, cool coloration, almost pure white underneath, with the only green tones in the wing and tail fringes, 'tobacco-stained' ear coverts and jet black legs and feet with yellow soles, Ross Castle, February 2015 (D.Farrar/B.O'Mahony).
Siberian Chiffchaff, Ross Castle, February 2015 (M.O'Clery).
The paper above also notes the intriguing statistical possibility that, going on the number of unringed Chiffchaffs (of all races) seen in the area after ringing took place, that up to 100 individuals were present.
(Irish Birds journal is available to buy on the BirdwatchIreland website HERE).