Tuesday, 4 December 2018

Returning Black-heads

No lotions, potions or squeezing required in this case as the returning Black-heads, as you will have realised, are Black-headed Gulls. I started checking the gulls that come to bread at Orrell Water Park back in October and I was really pleased to find IA141745 was present on 08/10/2018. This bird was ringed as an adult on 29/04/2012 at Bohmke und Werder, Germany, near the Baltic coast and border with Poland, and has been recorded at Orrell Water Park each winter since then.

Black-headed Gull IA141745 back for its 5th winter.
This photograph was taken yesterday but it has been present since 08/10/2018, at least.

The next ringed Black-head to return was photographed on 29/10/18 and was another German bird. This bird was originally ringed as a nestling on 10/06/2016 at Esterweger Dose, Weser-Ems in north-west Germany and was previously recorded at Orrell Water Park from 02/10/2017 to 17/03/2018.

Black-headed Gull 5437612
Photographed on 29/10/2018 and recorded several times since, most recently on 29/11/2018.
A check of the gulls on 11/11/2018 produced another returning bird but this time it was a British ringed Black-headed Gull EZ33149. This bird was ringed as a nestling on 20/06/2017 at Elvanfoot, South Lanarkshire and was previously recorded at Orrell Water Park between 10/11/2017 and 17/03/2018.

EZ33149 just wouldn't stand still for very long so I concentrated on getting photographs of the ring rather than the bird. I only just managed to get the full number but it took 25 photographs along with a lot of cropping and some enhancement afterwards.
Only 4 ringed Black-headed Gulls were recorded at Orrell Water Park in the whole of last winter so to have 3 of them back already is a very good return rate and shows how site faithful they can be.

Saturday, 17 November 2018

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.

Friday, 9 November 2018

Collybita, abietinus or tristis: the Chiffchaff conundrum.

Regular readers of the blog may remember that I caught a very interesting looking Chiffchaff back in September (link here). Its largely greyish-green and white livery was very different to the standard olive-green and mustard-yellow of the nominate race (collybita) Chiffchaffs that I normally catch in autumn. I thought it was likely to be a Chiffchaff of the race abietinus (the range of which includes large parts of Scandinavia, parts of eastern Europe and European Russia) but, as I commented in that earlier post, I also thought it had a look about it that potentially gave it more easterly credentials, although the early date (23/09/2018) seemed to make that unlikely.

Luckily I was able to salvage a few small feathers that it dropped in a bird bag and submitted them to Professor Martin Collinson for DNA analysis. I was certain that it would prove to be a very interesting individual whatever the result of the DNA analysis turned out to be:
  1. It would be very interesting if it turned out to be collybita simply because its appearance is so unlike that of collybita.
  2. It would be equally if not more interesting if it proved to be abietinus as very few have been confirmed by DNA in western Europe and also because there had been no easterly winds up to that point in September to help drift a migrant of such origin to the UK (especially the west side of the UK).
  3. It would also be very interesting (if not remarkable) if it was shown to have tristis origins because of the early date, again because there had been no easterly winds up to that point in September and because its abietinus like appearance would point to it being a abietinus x tristis hybrid.
Greyish-green and white Chiffchaff caught at Billinge 23/09/2018.
Unfortunately it was not heard to call so there were no clues there. Its appearance most closely matches the descriptions for abietinus but I also knew the identification of abietinus was not necessarily that straightforward. A genetic study of migrant Chiffchaffs caught in the Netherlands found that all 23 of the birds that were identified by ringers as being abietinus, based on their appearance, turned out to have tristis mtDNA (de Knijff et al.)

The flanks were washed with pale brown similar to a tea or coffee stain on a white cloth.

The belly, breast and throat were largely white. The undertail coverts were similar to the flanks but there was a stronger buff to yellowish-buff suffusion around the vent.

The supercillium had yellow tones above and in front of the eye but was pale brown and much less distinct behind the eye. 
To say the result was eagerly awaited is a bit of an understatement and my interest was heightened after reading a paper on the genetics of Chiffchaffs caught in Britain and Ireland (Collinson et al.that was published in British Birds earlier this year (link here). That paper looked at the genetics of 149 migrant and wintering Chiffchaffs caught during 2009 - 2017. It was interesting to see that only 9 birds in that study were found to have abietinus mtDNA and only one of those 9 was actually identified as abietinus by the ringer with the other 8 being tentatively identified as collybita or at least 'not tristis'. As for timing of autumn occurrences the few abietinus were within the same period that tristis were found with the earliest of either race being a tristis caught on the Isle of May on 28/09/2015. The study also found one Chiffchaff that was submitted as a potential tristis actually had collybita mtDNA, however, its quite dull grey appearance was considered to be unlike any of the Chiffchaff races and it was suggested that it was an aberrantly plumaged collybita.

Well I didn't have to wait too long to get the DNA result and I received an email from Thom Shannon, a PhD student working with Martin Collinson, saying that the mtDNA they recovered was that of a tristis Chiffchaff. Thom also commented that the plumage was a much better fit for an abietinus type and that they were of the opinion that it was a clear abietinus/tristis intergrade. As I said earlier the result was going to be interesting whichever way it went and to my mind the combination of its abietinus type appearance, its tristis mtDNA and the early date is the most intriguing outcome of all. 

For those of you that may not know mtDNA is only inherited through the maternal line so it only tells us that its Mum, Grandma or a direct female relative further back through the generations was a 'pure' tristis Chiffchaff. There is no way of knowing from the mtDNA or the bird's appearance if its genetic make-up is more tristis than abietinus or vice versa. Some may be tempted to think it is more abietinus than tristis because its appearance is a much better fit for abietinus but genetic studies on the breeding grounds have shown that is not necessarily the case (Shipilina et al.; Marova et al.). In those studies some birds with abietinus morphology (appearance) were found to have tristis mtDNA and a predominance of tristis DNA overall.

So the mismatch between the Billinge bird's appearance and its mtDNA points to it being an abietinus/tristis intergrade (hybrid) and one thing we can we can say with some certainty about such intergrades is where they originate. The contact zone (the area where the two races meet and overlap) is a relatively narrow band running from the southern Urals northwards to the White Sea and genetic studies have shown that past and ongoing hybridisation occurs in this area and that a similar mismatch of appearance and mtDNA is not found in other parts of either subspecies breeding range (Marova et al and Shipilina et al). Therefore, it is reasonable to conclude that this particular bird originated in that contact zone and will have travelled around 3250 km to reach Billinge.

Approximate zone of contact between abietinus and tristis (redrawn from Shipilina et al. and Marova et al.) and location of the site where the bird was caught.

There are other aspects to this record that make it particularly interesting with the early date being one of them. The Billinge bird is a week earlier than the earliest tristis identified in genetic study by Collinson et al and if you factor in the westerly location and absence of easterly winds up to that point in September it makes that early date even more exceptional. We will never know when it actually arrived in the UK but it was presumably at least a day or two before the capture date at Billinge, if not longer. In addition, it is a bird that calls into question what we know or think we know about the likelihood of abietinus occurring in western Europe and the UK in particular. I appreciate it is not safe to draw any firm conclusions from just one individual but if abietinus is the regular, if relatively scarce, passage migrant it is generally thought to be then the Billinge bird should have had a much greater chance of being found to have abietinus mtDNA as opposed to the tristis mtDNA that was found.

I am no expert on the subject but I would have thought there are far more 'pure' abietinus in this world (birds with abietinus appearance and abietinus mtDNA) than there are abietinus looking hybrids that have tristis mtDNA, especially when you consider the large range that abietinus occupies west of the overlap zone and the relatively small area of overlap zone itself, where all abietinus x tristis intergrades are thought to originate. It has been suggested, by some who know far more about this subject than me, that many abietinus are so similar to collybita that they probably go unnoticed in western Europe but even if that is the case I would have still thought that should leave enough abietinus that look sufficiently different to be picked out with relative ease, at least in the hand if not in the field. More importantly I would have also thought it more likely that those abietinus that can be identified from their appearance should still outnumber abietinus/tristis intergrades with abietinus morphology, assuming they are the regular and more common passage migrant that presumed wisdom suggests.

As I said earlier it is not safe to draw any conclusions from one individual but the Billinge bird is another record that adds to the uncertainty that surrounds the true status of abietinus as a migrant to the UK. In addition it extends the period when birds of tristis origin can occur and, if nothing else, is simply a very interesting record in its own right as we can be reasonably certain of the region it came from.

Collinson, J.M., Murcia, A., Ladeira, G., Dewars, K., Roberts, F. & Shannon, T. 2018. Siberian and Scandinavian Common Chiffchaffs in Britain and Ireland - a genetic study. British Birds 111: 384-394.

Shipilina, D., Serbyn, M., Ivanitskii, V., Marova, I. &  Backström, N. 2017. Patterns of genetic, phenotypic, and acoustic variation across a chiffchaff (Phylloscopus collybita abietinus/tristis) hybrid zone. Ecology and Evolution 2017; 1–12.

Marova, I.M.,
Shipilina, D., Federov, V., Alekseev, V. & Ivanitskii, V. 2017. Interaction between Common and Siberian Chiffchaff in a contact zone. Ornis Fennica 94: 66-81.

de Knijff, P., van der Spek, V. & Fisher, J. 2012. Genetic identity of grey chiffchaffs trapped in the Netherlands in autumns of 2009 - 2011. Dutch Birding 34: 386-392.

Monday, 29 October 2018

Billinge 29th October 2018

I wasn't sure what to expect after my week away, more so given the clear and frosty start, but it ended up being quite a good session for late October. There were a few thrushes moving early on resulting in 9 Redwings, a Fieldfare, and a Blackbird being caught but they soon fizzled out. There wasn't much in the way of visible migration, once the thrushes had stopped, but a Crossbill and a few high flying Siskins were noted along with a small movement of Woodpigeons. The most interesting sighting came mid-morning when a Woodcock (my first of the autumn) landed on the track near to where I was stood, it took a few steps and then fanned its tail and raised it over its back in the manner of a Black Grouse but then it noticed me an flew off. I have never had such a good view of a Woodcock before or seen one tail fanning so that was a nice bonus.

The nets continued to produced a few birds after the initial rush of thrushes and the final total of 36 new birds and 1 retrap was quite a good result, all things considered. There were no surprises but 10 Goldcrests was a good number and a flock of Long-tailed Tits helped bulk the numbers too, while a female Sparrowhawk caught in the last round was a great way to end the session.

Ringing totals (retraps in brackets) for 29/10/2018 were: Sparrowhawk 1; Coal Tit 2; Blue Tit 2; Great Tit 1; Long-tailed Tit 7 (1); Goldcrest 10; Robin 1; Blackbird 1; Fieldfare 1; Redwing 9; Lesser Redpoll 1.

This 1CY female Sparrowhawk was in one of the nets when I went to take them down at the end of the session. I have done quite well for catching female Sparrowhawks this autumn as they are usually very good at getting out of mist-nets.

Billinge 18th & 19th October 2018

I didn't get chance to write reports on these visits before going away on holiday, or while I was away for that matter, but I felt there was enough of note to merit this belated summary.

The most notable feature of the 18th was the number of Goldcrests present with the 27 ringed being the highest total of the autumn in terms of new birds but equalling the 26 new and 1 retrap that were caught on 7th October. Thrushes made up much of the rest of the catch with 21 Redwing and 4 Song Thrush keeping me busy in that first hour or so around sunrise.
Ringing Totals for 18/10/2018 were: Coal Tit 1; Great Tit 2; Goldcrest 27; Redwing 21; Song Thrush 4; Chaffinch 1; Lesser Redpoll 2.

Goldcrest 18/10/2018
The 19th saw a big change in the number of Goldcrests present with only 2 ringed and there were fewer thrushes around too. However, there were more finches moving with a good movement of Bramblings in particular. I wasn't able to keep track of the numbers of Bramblings involved but the flocks and groups I counted in between net rounds just got into 3 figures so I am sure the true figure must have been far higher. A few Bramblings also found their way into the nets and 5 were ringed (first to be ringed this autumn).
Ringing totals for 19/10/2018 were: Goldcrest 2; Redwing 9; Brambling 5; Lesser Redpoll 5.

Male Brambling 19/10/2018

Tuesday, 16 October 2018

Coal Tits on the move.

The highlight of this mornings visit to Billinge was the capture of 15 Coal Tits which is the highest total for the site by some margin. They were all caught towards the end of the session with a flock of 7 being caught at 10am and a flock of 8 an hour later. The previous day record of 8 was only set on 7th October this year so it is clear there is much more movement going on than usual. Some vis-mig sites around the country are recording similar irruptive behaviour so it is a widespread phenomena. It's not just happening in the UK either as Falsterbo Bird Observatory, in southern Sweden, is also ringing above average numbers of Coal Tits and is on track for one of their highest autumn totals.

One of this mornings Coal Tits, 
Ringing totals for 16/10/2018 were: Coal Tit 15; Blue Tit 2; Great Tit 5; Blackcap 1; Goldcrest 7; Nuthatch 1;  Redwing 14; Song Thrush 5; Robin 1;Lesser Redpoll 3. Total 54 new birds.

Monday, 15 October 2018

Sparrowhawk double

It had to be a shorter session than usual at Billinge this morning because I had an appointment to go to but it turned out to be interesting nevertheless. There weren't many thrushes moving but over 2,000 Woodpigeons were counted going south by 9:00am (per CAD). A single Brambling was the first of the autumn and another or the same was heard again later. There were no warblers, not even a Chiffchaff, but Goldcrests found their way into the nets at regular intervals and a total of 13 were ringed. A couple of Sparrowhawks livened things up with a 1cy male being caught first and a 2cy female being caught in the same net an hour later. Catching 2 Sparrowhawks in the same session doesn't happen very often but the 3 previous occasion it has happened have all been in mid October like today's double act. The lively theme continued when a rather feisty Jay was caught and it did its best to take lumps out of me, as they usually do. The last net round produced a group of 5 Lesser Redpolls and, interestingly, 4 of the 5 were adult males which continues the predominance of adults in the Redpolls caught so far this month.

1cy male Sparrowhawk

1cy male Sparrowhawk

2cy female Sparrowhawk

The female Sparrowhawk had an unusual and very hard accretion on the tip of one of its claws. I have never seen anything like this before and have no idea what could have caused it..

Ringing totals (retraps in brackets) for 15.09.18 were: Sparrowhawk 2; Jay 1; Coal Tit 2, Blue Tit 1; Great Tit 1; Goldcrest 13; Blackbird 1; Song Thrush 3 (1); Bullfinch (2); Lesser Redpoll 5. Total 29 new birds and 3 retraps.