White Spots, Orange Spots, Red Spots and No Spots – take care!
A big thanks to Stephen Menzie for providing these notes exploring variation in White-spotted Bluethroats:
“I went out to Catalonia earlier this year happily referring to Bluethroats as ‘red-spotted’ or ‘white-spotted’. I came back referring to them as svecica and cyanecula. Partly because, whilst ringing in a foreign country, Latin names tend to get you further than English names do; mainly though because ‘white-spotted’ implies the birds’ spots were always white, which was far from the case!
A recent paper in Birding World (23:7) by Enno Ebels and Nils van Duivendijk looking at ‘orange-spotted’ Bluethroats in the Netherlands served to reinforce the less than simple divide in morphology between svecica and cyanecula.
From a British point of view, it seems we might have to rethink our willingness to call any Bluethroat showing a reddish spot in the throat “Red-spotted”.
There are no accepted records of svecica (Red-spotted) Bluethroat in Catalonia, where all of these photos were taken, so all of these birds should be cyanecula (White-spotted). Ringing recoveries suggest birds wintering in Catalonia come mainly from Belgium. No birds caught were large enough to be svecica (though there is overlap in wing length between the two forms) and close examination of birds’ plumage indicated the all birds were almost certainly not svecica. It should also be noted that Bluethroats are one of the most uncooperative birds to photograph with a lot of wing flicking; it’s therefore not desirable to keep them in the hand for too long, resulting in a lot of ‘grabbed’ photographs before the bird’s release with the bird in less-than-ideal (often rather ugly) poses.
The first two birds are rather typical and easily identified as ‘white-spotted’ cyanecula birds.
Notice how much narrower the rufous stripe below the blue bib is on the 2cy bird compared to the adult. However, it seems this might not always be a clue for ageing.
The bird in the following to images was also aged as a 2nd cy (1st summer) bird.
It looks like immature birds can show a wide rufous band but could an adult ever show a band as narrow as that on the first immature bird? The following bird, an adult, showed less visible white on the throat spot, though the white would still be visible in the field.
The next bird, also an adult, would show no visible white in the field in a normal ‘resting’ posture.
However, a slightly ruffled throat feather gives away the birds true identity as cyanecula; the feather bases at the centre of the blue bib are extensively pure white.
This white would most likely be visible if the bird was to sing or have its feathers displaced by e.g. strong wind. The final bird, a 2cy, is potentially the most interesting and likely to invite the most confusion.
The central throat spot is certainly neither white nor blue! But is it red? I have no first-hand experience of svecica birds so I’m not well placed to comment but it certainly doesn’t strike me as being the strong blood-red typically seen on that form. The red spot also seems to be on the small side for a typical svecica. Could this be one of the ‘orange-spotted’ birds from the above-mentioned Birding World paper? With a wing length of 75.0 mm, this bird would be at the small end of the range for svecica but fits nicely into the middle of the range for cyanecula. Yet again, the feather bases at the centre of the throat seem to hold the best clue to assigning the bird to race.
The feather bases are a rather extensive pure brilliant white, sharply contrasting with the blue at the lower edge of the ‘spot’ but with the orange-red bleeding slightly into the white at the centre of the spot. This should rule out svecica, which are reported to show “a grey [feather] base, then some white in the middle, then sharply demarcated deep red on the outer 5-6 mm” (Kees Roselaar in Ebels & van Duivendijk Birding World paper). Whilst these feathers do show some grey at the very base, this description probably doesn’t fit with what we’re seeing here – comments from anyone with experience of this more than welcome, though!
from Nils van Duivendijk, co-author of the Birding World paper:
Firstly, I like your Birding Frontiers blog very much! Great job to put these enjoyable and very interesting issues on the net every day!!
Stephen Menzie’s contribution on the Bluethroats is again very interesting and the ‘orange-spotted’ bird is indeed the thing Enno and I were talking about in the BW article: almost certainly a cyanecula [White-spotted]. These feathers seem to be fresh, looking moulted in the same period as the other breast-feathers (however difficult to be sure from a photograph only). We have to be more cautious where individuals retain ‘old winter-feathers’ possible in some cases – as suggested in the BW article (especially extreme male-like females). [Many White-spotted Bluethroats show orange central breast feathers in autumn after the post-breeding moult (making them inseparable from Red-spotted) but these are normally moulted to white feathers in the early spring pre-breeding moult.] Maybe Stephen has some comments on this? Please find a picture of the base of the spot-feathers of a svecica [Red-spotted Bluethroat] with grey base, narrow white band and large red distal part (Nationaal Natuurhistorisch Museum Naturalis, Leiden).
It seems a male Bluethroat showing a white, or even blue, throat-spot in the UK should be safe to call cyanecula. A bird showing a red or reddish throat-spot might need a closer look, though, since this could in theory be either a svecica bird or a ‘red/orange-spotted cyaneclua’. It seems that, in the field, the shade and saturation of the red and the size and shape of the spot itself are key to assigning the bird to race. In the hand, close examination of the base colour of the throat feathers should, in combination with wing length, help to assign the bird to one form or another. With an increased awareness it will be interesting to see how common ‘red-spotted cyaneclua’ birds are in the UK and how these birds fit in with what is known about the Dutch ‘orange-spotted’ birds. It also begs the question how many reported ‘red-spotted’ birds early in the season might be been misidentified ‘red-spotted cyanecula’.
And finally, for something (probably) unrelated, take a look at the level of variation shown in the colour of male Bluethroat undertail covers.
It seems that age plays no part in the variation while any correlation between e.g. width of rufous band below the bib and undertail covert cover certainly isn’t immediately obvious!
Stephen Menzie August 2010
(prepared for web by Tristan Reid)