Posted for James Siddle who is in the process of joining the LBC
It’s certainly been very interesting reading all the responses. Having lived in Portugal for several years where I rarely met another birder, it has been most enjoyable for me to read such erudite and interesting responses to the original post.
I agree with GPC about the likelihood of late migrating Stonechats being first summers. I did try to age the Gib bird, as there seemed no obvious contrast between the remiges and the wing coverts and I suspected this bird to be an adult. However, with difficult viewing conditions (high winds, poor light and sea mist!) I am far from certain about this.
As GPC says it has been mooted that the Stonechat population is merely clinal of a single race. The Dutch CSNA, for example, have treated hibernans as a synonym of s. rubicola. Additionally, Urquhart(2002) also emphasises the great difficulty in separating the subspecies, especially where the populations meet.
In terms of range, according to Urquhart hibernans breeds in ‘western and possibly southern Norway, the UK, south to France (western Brittany) and the west coast of Portugal’. With rubicola the ‘northern boundary of this subspecies borders the North Sea stretching along the coasts of France (excluding western Brittany) Belgium, Netherlands and Germany to Southern Denmark.’ Eastwards I have noted rubicola breeding in Armenia, whilst recent research suggests that in may also occur in Iran (Kirwin and Bates in prep). ‘The western limits of its range extend southwards down the Atlantic coast of Europe to the Iberian peninsula (apart from western Brittany and Portugal)….it inhabits North Africa from Morocco through northern Algeria and northern Tunisia’. From ringing recoveries the vast majority of UK ringed birds recovered on the continent have been from Spain, although one reached as far south as Morocco. There is also an example of a Spanish ringed bird recovered in the UK, which may, on date, have been a rubicola rather than a returning British bird.
With regard to the morphology of the Stonechat population at the extremes of the range i.e. from Norway and Scotland and the Mediterranean basin there is, in my opinion, a distinct plumage variation. The problems occur in the intergrade zone between the populations, of which we may lie towards any hypothetical boundary areas (perhaps the fulvescens population of the, admittedly much more widely distributed, Chiffchaff would be analogous). In Portugal (where as I have previously stated the whole population resembles rubicola rather than hibernans) the males there often recall Siberian Stonechat having large, often almost unmarked white rumps, often pale fringes to the lower back feathers even in early spring, a broad blaze of white across the necks extending round the nape, extensive white in the in the wing, limited orange colouration in the underparts and very dark underwing coverts. These birds are very distinct from those in the northern Britain.
Assuming both subspecies are valid, whether the pale birds we are seeing in the UK are rubicola or hibernans is, obviously, extremely difficult to say. However, birds exhibiting a combination of characteristics typically associated with rubicola appear to occur as both migrants and in the breeding population. This breeding population may be confined to southern England (?). For example, when I lived on Scilly of the breeding Stonechat population I checked there (approx. 60 pairs) less than 5% showed characteristics of rubicola. With the populations north of Lincs grading towards the dark extreme of hibernans, rather than these pale birds, would it seem unlikely that the Gib bird was thus a bird heading north as GPC suggests?
In addition, as already mentioned by Stephen, a small number of these interesting looking birds are now being regularly reported at well watched sites on the south coast, for example Dave Walker at Dungeness reports ‘rubicola-type’ birds on the 12th and 14th March. Personally, I feel the case is very much open on these birds. I wonder, for example, if any of the ‘100 plus or possibly double that’ which passed through GPC’s local area in 10 days showed similar features?
_________________ ----------------------------------------------------- Andrew Chick Website: http://www.forktail.co.uk/
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