Icelandic Redwing Recovery

When I received a recovery report for a Redwing I had identified as being of the Icelandic race and it had actually been recovered in Iceland I was more than a little pleased and surprised, to say the least. I have ringed 3675 Redwings on Billinge Hill and at Crawford since 2014 but only a very tiny proportion of those have been of the Icelandic race 'coburni'. Add in the relatively low recovery rate for Redwings of roughly 1 in 500 from my ringing and 1 for every 1166 from all ringing in Britain and Ireland up to 2020 (BTO online ringing report) and there was very little chance of having one of my Icelandic Redwings recovered anywhere, let alone in Iceland. In terms of likelihood getting this recovery report was a bit like winning the lottery.

Redwing (Turdus iliacus coburni)

RY31104    first year    17/11/2018    Billinge Hill, Billinge, Merseyside, UK

Caught by ringer          25/03/2022    Akureyri, Norður, Eyjafjarðarsýsla, Iceland

Duration: 1224 days     Distance: 1600 km     Direction: 328deg (NNW)

When I looked at the recoveries in BTO online ringing report there had only been 32 Redwings recovered in Iceland from all ringing in Britain and Ireland up to 2020. Of those 32 recoveries 29 had been ringed in Scotland, 1 in Ireland, 1 in Wales and again only 1 in England. An analysis of Redwing recoveries by R.D.P Milwright using data from birds ringed in the breeding season indicated that Icelandic Redwings winter almost entirely in Scotland, Ireland, western France and northwest Iberia. Also that adults and birds from eastern Iceland are more likely to be recovered in Scotland and Ireland while those from Western Iceland are more likely to be found in France and Iberia.

I have had a long standing interest in Icelandic Redwings which started in the early days of my ringing when I was with Leigh Ringing Group and we used to catch large numbers of Redwings at a roost site near Bolton. In those days I used to wonder how difficult or easy it would be to identify 'coburni' given they were generally described as averaging a bit darker and longer winged. Not only that but did they even occur in north-west England given what was known and published at that time. Back in those days, like many ringers, I used to think the best initial clue would be size with any long winged bird (126mm+) being a candidate for the Icelandic race but that ignores the fact that there is a huge overlap in the range of wing lengths the 2 races display. If my memory serves me correct we didn't catch any particularly long-winged Redwings at that roost site, certainly none that would be outside the normal range of the nominate race 'iliacus' and nor did any appear to be noticeably darker.

My interest in this subject was revived when I started ringing on Billinge Hill in 2014 and found I was able to catch large numbers of Redwings from migrating flocks in autumn with the help of a new sound lure. On 16th November 2014 I caught a Redwing that was noticeably darker but I was cautious and only tentatively suggested it could be an Icelandic bird and wrote about it in a blog post here. On 20th November 2014 I caught another dark and heavily marked Redwing and this time I was convinced it must be an Icelandic Redwing. It had a wing length was 127mm, so was quite big but not necessarily outside 'iliacus' range, depending on which reference you use. It also made me realize that I had been too cautious with the individual I had caught a few days earlier and that too was an Icelandic bird. This second bird resulted in me writing a blog post Redwings: coburni v iliacus (link here) which has become one the most popular posts on this blog, such is the interest in separating the two races.

While I had become happy that I could pick out well marked Icelandic birds regardless of their wing length I was still left wondering how similar in appearance to 'iliacus' some of them might be and I still don't know the answer to that one. Since those first two Icelandic Redwings I have caught a few others in most autumns (usually in late October or November) but I have also caught others that I considered fell short in terms of appearance to varying degrees. My ringing notebooks are littered with notes on the appearance of Redwings and it is why I can't put an exact number on how many Icelandic birds I have actually ringed because I may have been too cautious in some cases. Some were put down as definite 'coburni' and that number only gets into low double figures but others were put down as possibles or probables for one reason or another. I have also caught a quite a few long winged birds that appeared to be typical 'iliacus' in terms of appearance but had wing lengths of 127mm and 128mm. However, the two longest wing lengths I have recorded were 128.5mm and 129mm with the first individual being considered to be a definite 'coburni' on appearance (images of this individual can be seen in a blog post here) but second was only noted as being a bit darker than typical 'iliacus' and was only considered to be a possible 'coburni', partly based on its 129mm wing length. Another interesting point about the latter bird is that it was caught on 3rd October 2016 during an early movement of 'iliacus' and would seem to be too early for a bird of Icelandic origin to reach north-west England, not to mention the issue of different weather patterns that would influence the movements of the two races in reaching the UK.

While I was happy I was catching a small number of Icelandic Redwings there is no substitute for some form of proof especially as the race could be considered a county rarity or even an English rarity. Statistically I knew the chances of catching a bird that had been ringed in Iceland or having one of my birds recovered there was so incredibly low that it was never likely to happen. I wasn't likely to go to Iceland to look at Icelandic Redwings on their breeding grounds to study their appearance either. I also investigated the possibility of confirming the identity of some of my Icelandic birds through DNA from feather samples but that failed to get the necessary support at the time. So when the recovery report for RY31104 landed in my inbox a few days ago the proof I never expected to get was actually there.

I only caught 12 Redwings on 17th November 2018 and 3 of them were what I described as stand out examples of the Icelandic race, 'coburni', in a blog post at the time (link here). Unfortunately I only photographed one of these Icelandic birds and it wasn't the bird that produced the recovery. The wing lengths of these 3 'coburni' were 126.5mm, 125mm and 122mm with the bird that was recovered in Iceland having a wing length of 125mm.

Icelandic Redwing 17//11/2018

Icelandic Redwing 17//11/2018

Icelandic Redwing 17//11/2018

This recovery and my ringing records of Icelandic Redwings hopefully go some way to show that they occur more regularly in northwest England than had previously been known or even thought. I hope my blog posts and photos have gone some way to show that separating the two races is best based on appearance rather than being distracted by consideration of wing length. What I can't tell you is how similar in appearance some individuals of the two races may actually be but I suspect, as recorded in my ringing notebooks, there will be some slightly darker birds that can't be confidently recorded as 'coburni' but probably or possibly are and others may just may be well marked 'iliacus'. As for wing length, in my experience, even some quite long-winged birds with wing lengths of 127mm and 128mm, that look like nominate 'iliacus' are probably just that, long-winged 'iliacus'. If it was too easy it wouldn't be worth doing, would it.

References

Robinson, R.A., Leech, D.I. & Clark, J.A.(2021) The Online Demography Report: bird ringing and nest recording in Britain & Ireland in 2010. BTO, Thetford (http://www.bto.org/ringing-report, created on 27-June-2020)  

R. D. P. Milwright (2002) Redwing Turdus iliacus migration and wintering areas as shown by recoveries of birds ringed in the breeding season in Fennoscandia, Poland, the Baltic Republics, Russia, Siberia and Iceland, Ringing & Migration, 21:1, 5-15, DOI: 10.1080/03078698.2002.9674271

Icelandic Redwings & Sparrowhawks

I only had time for a brief ringing ringing session at Billinge this morning but it turned out to be well worth the effort. A total of 12 Redwings, 3 Goldcrests and 1 Sparrowhawk were caught in little more than an hour which isn't bad going for mid November, especially as only 2 nets were used. The Sparrowhawk was a new female and another that failed to do the usual last minute climb out of the net and escape trick. However, it was the fact that 3 of the Redwings were stand out examples of the Icelandic race, coburni, that made it particularly worthwhile.

The upperparts of Icelandic Redwings tend to be a shade darker overall but it is the much heavier (blotchier) and more extensive streaking of the underparts, dark brown legs and toes, and well marked under-tail coverts that make them really stand out from continental birds (nominate race iliacus).

Icelandic birds average bigger too but in my experience wing length is of limited value as most will fall in the overlap between the two races. This bird had a wing length of 126.5 mm and was noticeably bulkier than the iliacus that were caught at the same time. However, it still falls within the overlap as iliacus can have a wing length of up to 129 mm (yes 129 mm and I have caught one that big myself) although most publications used by ringers only give an upper limit of 126, 127 or 128 mm. 

November and mid November in particular seems to be a good time for Icelandic Redwings at Billinge; my first were recorded in mid November 2014 (link here)

Today's 1cy female Sparrowhawk was the 4th female of the autumn.

While on the subject of Sparrowhawks I managed to get a photograph of a cracking little male that caught a Goldfinch in the garden a few days ago. It was already wearing a ring and I was able to read part of the number which suggests it is one that I ringed at Billinge in autumn 2015 but that is as far as I could narrow it down.

Male Sparrowhawk 12/11/2018

Easterly winds have set in and are forecast to continue for a good few days so it will be interesting to see if they bring anything unusual this way. They could pep up thrush movements initially, if nothing else. I just hope they are not too strong and give me the chance to get some nets up.

Billinge: 11th & 13th November

It is that time of year when ringing forays on the hill go all country music which is OK if you don't mind slim pickings. The first hour or so usually manages to provide a few birds but the capture rate usually tapers off quite quickly and the remainder of the session often feels like there would be plenty of time to start learning to play the banjo. While the quantity and variety may not be there a degree of quality usually is and there is always a chance that something really interesting or unusual may turn up.

A fog hampered session on the 11th produce a total of 18 birds - 4 Goldrest, 3 Blackbird, a Fieldfare, 7 Redwing and 3 Chaffinches. Two of the Blackbirds were quite long-winged so likely to be of continental origin as were a couple of the Chaffinches. There haven't been as many Fieldfare passing through this autumn so catching one was a real bonus.

Adult female Fieldfare 11/11/17

A session in clearer conditions on the 13th also resulted in a total of 18 birds being caught - 5 Goldcrest, 12 Redwing and a retrap Robin. The stand out highlight of this session was an Icelandic Redwing which stood out as looking different even as I approached it in the net.

Previous posts with images of 'coburni' types have always attracted a lot of views and there is clearly a lot of interest in the identification of Icelandic Redwings. Some people think wing length is the key to identifying Icelandic birds but there is a huge overlap between 'coburni' and and the nominate race 'iliacus' and wing length will only identify the biggest 'coburni'. Icelandic birds are generally darker and more heavily marked than the nominate race and while that can lead to a bias of only identifying the darkest and most heavily marked birds it will identify more birds than wing length. Anyway you can decide for yourself by looking at the images below and the previous ones I have posted here and here.

Note the brownish-buff washed ground colour to the heavily marked flanks and undertail coverts.

Obviously the Icelandic bird is on the left with a nominate 'iliacus' on the right for comparison.

By the way there is a country music outfit called Slim Pickins and there is another band called Slim Pickings although they play different genre altogether, not that either is really my cup of tea.

Another Redwing recovery, 1011 ringed and a 'coburni' too.

Another recovery report for a Redwing landed in my inbox yesterday and gives further support to my view that most of the birds that migrate via Billinge in October and early November are heading for wintering areas much further south. While this movement isn't as quick as the recent recovery in Spain it still shows a good onward movement in the main migration period. It was almost certainly still on passage when recaptured on Guernsey and will probably spend the winter further south in France or Iberia.

RZ37675               Redwing      (first year)
Ringed                  12/10/2016   Billinge Hill, Billinge, Merseyside.
Caught by ringer   02/11/2016   Jerbourg, Guernsey, Channel Islands. 454 km S, duration 21 days.

Redwing passage appeared to have ended at Billinge by mid Novemeber, when the ringing total stood just under the 780 mark, but after a lull of around ten days there has been an upsurge in Redwing numbers/movements in the area that hasn't ended yet. This has resulted in another 232 Redwings being ringed at the Billinge and Crawford sites between 23rd November and today. Quite why this is is hard to say but a northerly (NW to NE) push of Redwings has been recorded at vis mig sites in Staffordshire and on the West Pennine Moors in the same period, including 3464 moving NW over Winter Hill on 29/11/2016.

I caught another 15 Redwings at Billinge this morning which brought the combined ringing totals for Billinge and Crawford to 1,011 and all since 3rd October; a good effort even if I do say so myself. I didn't take a photo of the thousandth Redwing but thousand and eighth certainly got my attention as it was a very obvious Icelandic Redwing, the first and perhaps the only one of this autumn. It didn't have a particularly long wing at 120mm but far too much is made of their wing length considering there is a huge overlap between the two races. The real indicator is their much darker appearance, not their wing length.

If a Redwing as dark and as well marked as this doesn't get your attention I don't know one that will.

The legs and toes were quite dark, although not as dark as some 'coburni', but darker than most 'iliacus'.

Strongly marked undertail coverts seem to be a feature of Icelndic birds. While the tail itself is broad and quite rounded there is plenty of wear.

A very obvious moult limit with 4 ogcs'; old tertials are present too. There is no doubt that this is a first year bird.

While on the subject of Redwings I will be updating the Redwing ageing page fairly soon. Any new information/images will be tagged on at the end and labelled as an update to make them easier to find.

Redwings: coburni v iliacus

I think I was a little too cautious in my post 'More of the same' (link here) with regard to the photograph of a Redwing that showed characters of the Icelandic race 'coburni'. I suggested its appearance possibly fell a little short of the mark but if anything fell short it was my experience of birds from the Icelandic population (nil up to then). I caught another dark and heavily marked bird yesterday and it stood out as much if not a little more than the previous bird did which prompted me to reconsider that earlier note of caution. It also prompted me to do some homework and I have been trawling the internet looking at photos of the races and reading up on the subject. I am now certain that yesterday's bird and the previous bird (caught 16/11/14) are Icelandic Redwings.

Birds of the Icelandic subspecies (T.i.coburni) are marginally larger and darker than nominate birds from northern Europe (T.i.iliacus) but only around 14% of Icelandic birds have longer wing lengths and therefore relatively few can be separated on size. Both birds had wing lengths that fell in the upper part of the overlap in the wing length ranges with yesterday's bird being 127mm (right on the upper limit) and the first bird had a wing length of 124mm. Published wing length ranges vary depending where you look but I have gone with 126/127mm as being the upper limit for nominate birds largely based on a paper that considered occurrences on Heligoland (Germany) which can be found here.

In terms of appearance 'coburni' is described as being slightly darker and are generally more heavily marked and having looked at a lot of images of both races there appears to be less overlap in appearance than there is in size. However I do feel there was a bias towards showing obviously darker birds amongst the examples of migrant 'coburni' photographed outside Iceland which is only to be expected when the separation of the races is not always clear cut. Another feature for separating the races is the colour of the legs and feet which are dark horn brown in 'coburni' and pinkish-flesh in 'iliacus' and this was very obvious and can been seen in many of my photographs.

Redwing of the Icelandic race 'coburni', Billinge 20/11/14

The following series of photos shows the same bird with a fairly typical bird of the nominate northern European race 'iliacus' that was caught the same day and photographed in similar conditions. 

'coburni' above and 'iliacus' below.

'coburni' left and 'iliacus' right.

'coburni' above and 'iliacus' below.

The following images are of the previous Icelandic bird caught on 16/11/14. On looking at these images again I don't know why I was cautious about fully attributing it to the Icelandic race. 

Redwing of the Icelandic race 'coburni', Billinge 16/11/14

Redwing of the Icelandic race 'coburni', Billinge 16/11/14 (same bird but appears to have a slightly paler throat and upper-breast from this angle).

Redwing of the Icelandic race 'coburni', Billinge 16/11/14

...and here is a collage showing how it compared with a lightly marked nominate bird caught the same day.

'coburni' left and 'iliacus' right.

The final image below shows a collage of both Icelandic birds with what I consider to be a heavily marked nominate bird (lower right) and a more typical nominate birds (top right). Although you can't really see much of the upper parts you can see enough to appreciate how much darker both Icelandic birds are. The upperparts of the Icelandic birds are what I would describe as a dark olive earth-brown whereas the nominate birds are more of a mid toned warm brown. The other thing to note in this image are the feet; darker horn brown coloured in the Icelandic birds (left) and pinkish-flesh coloured in the nominate birds (right). The strength, size and colour of the markings on the underparts largely speak for themselves but there is a little more variation in them.

Upper left 'coburni'; lower left 'coburni'; upper right 'iliacus'; lower right 'iliacus'.

If you are interested in comparing other images of migrant 'coburni' photographed in the UK examples can be found  here (Bardsey),  here (North Ronaldsay),  here (Fair isle),  here (Norfolk).

For images of 'coburni' taken in Iceland you can view images taken by Jakob Sigurdsson here and here. Other images by Gudmunder Geir's can be found here.

It is also worth a second look at the 'We Bird North Wales' blog post on this subject here.