'I don't believe it!'

I had a Victor Meldrew moment this morning, in fact I had several of them. The weather forecast for this morning wasn't brilliant but the rain cleared about a hour after sunrise and I ventured up to Billinge despite the stiff northerly breeze. I mainly wanted to see if any Tree Pipits would start to move after the rain had gone through but also took opportunity to put up a couple of nets in the sheltered rides of the NE corner of the site while I was there.

There didn't appear to be any Tree Pipits moving or much else for that matter and there wasn't much moving around in the bushes either. It was a surprise, therefore, to find a Tree Pipit in one of the nets on the second net round but that wasn't one of the 'I don't believe it' moments. The second net round also produced a single Willow Warbler and interestingly it was a new adult. Regular readers of this blog will know that I have been catching more adults than usual this autumn so catching another adult wasn't a huge surprise. When the next Willow Warbler also turned out to be a new adult I simply thought it was just one of those things that can happen by chance and that I would catch some juveniles in subsequent net rounds.

The catching rate was very slow but when the 3rd Willow Warbler of the morning also turned out to be a new adult I did start to think 'I don't believe it' and I may even have said it out loud. The next net round produced yet another adult Willow Warbler and another 'I don't believe it', this time the bird was a retrap that was last caught in April of this year. At that point I still thought I was likely to catch at least a couple of juveniles before I packed up because a catch that only included adults seemed so unlikely as to be unthinkable. When the penultimate net round produced another new adult, the 5th of the morning, it produced another 'I don't believe it' from me. The final net round drew a blank so it was a case of 5 adults out of 5 and not a juvenile in sight!.

I know its not a big sample but to catch 5 Willow Warblers on 9th August and for all of them to be adults is exceptional to say the least. It certainly underscores how unusual the juvenile:adult ratio has been at the site this autumn and I am sure it is a subject I will come back to again at some point.

Adult Willow Warbler 09/08/17. Four of the five had completed their full moult and the one that was still in moult had nearly finished.

Ringing totals for 09/08/17 were: Chiffchaff 2; Willow Warbler 4 (1); Blackcap 2; Tree Pipit 1.

Billinge 6th & 7th August: First Tree Pipits

It is that time of year when I expect to get my first Tree Pipits of the autumn and I wasn't disappointed with 1 ringed yesterday and another 3 today. None of them announced their presence by calling before they were caught and I didn't see any of them drop in as I usually do when passing birds are attracted to the audio lures. A total of 3 were seen yesterday but the 3 ringed today were the only ones recorded. Over the last 3 years the first autumn sighting has been between the 1st and 7th of August so yesterday's birds were pretty much bang on time.

Tree Pipit 06/08/17

Other highlights from the 2 sessions were the capture of 4 Garden Warblers and 5 Whitethroats; the latter qualifying a highlight because I only managed to ring 1 Whitethroat in the whole of July. Another 6 juvenile Goldcrest supports my previous comments about the species having a productive breeding season. Goldcrests have a long breeding season and many pairs are probably still churning out more young so it may turn out to be another bumper year.

Garden Warbler 06/08/17

Ringing totals for 05/08/217 were: Goldcrest 3; Blue Tit 18; Great Tit 2; Coal Tit 1; Chiffchaff 3; Willow Warbler 17(4); Blackcap 3; Garden Warbler 3; Whitethroat 2; Wren 1; Blackbird 1; Tree Pipit 1; Chaffinch 2; Bullfinch 1. Total 58 new birds and 4 retraps.

Ringing totals for 06/08/17 were: Goldcrest 3; Blue Tit 3; Chiffchaff 2, Willow Warbler 8 (2); Garden Warbler 1; Whitethroat 3; Wren 1; Song Thrush 2; Robin 1; Tree Pipit 3; Bullfinch (1); Goldfinch 1. Total 28 new birds and 3 retraps.

Billinge 28th to 31st July 2017: More adult Willow Warblers

The weather hasn't been particularly favourable but I managed to get out on the last 4 days of July. I went up to Billinge and set 3 nets in on each occasion although I had to change the net positions on some days to get adequate shelter from the breeze. The 29th provided the best conditions but the sessions on the other days were restricted by light showers and or a strengthening breeze.

I made the effort because I was curious to see how many juvenile and adult Willow Warblers I would catch and if the proportion of juveniles would increase. A total of 100 birds (92 new & 8 retraps) were caught over the four sessions and almost half  (43 new & 4 retraps) were Willow Warblers. Interestingly, the proportion of adult Willow Warblers remained relatively high with 11 out of the 47 being adults, although one had been encountered earlier in the month.

Adult Willow Warbler showing quite an extensive pure white belly.

 The total number of individual Willow Warblers handled in July ended up at 104 and of these 77 were juveniles and 27 were adults which gives a simple ratio 2.85:1. While this is the lowest ratio of juveniles to adults encountered in any July the total number of juveniles handled this July is similar to 2014 & 2015 as can be seen from the table below. 2016 seems to have been an exceptional year for juveniles as a similar pattern was found when I looked at the July totals for Chiffchaff  (2014/42, 2015/45, 2016/73, 2017/40) and Blackcap (2014/35, 2015/42, 2016/65, 2017/41). So the number of juvenile Willow Warblers encountered this July has ended up in what might be considered the 'normal' range for the site.

July Willow Warblers
Year	Juveniles	Adults	Ratio (rounded off)	Visits
2017	77	27	3:1	13
2016	101	6	16:1	13
2015	71	14	5:1	11
2014	81	9	9:1	13

A ratio of just under 3:1 is much closer to the actual productivity of Willow Warblers but that is not what I am used to seeing at this site, hence my interest being sparked by the high number of adults encountered this year. There did seem to be more adults around in the spring so better over-winter survival resulting in a higher breeding population may have played a part, although it appears to be too much of a increase to account for it all. If a much higher breeding population was part or all of the cause then it still suggests productivity is low this year as more pairs would be expected to produce more offspring unless productivity has been negatively affected in some way. There is also the possibility that some of the adults were migrants rather than local birds as some were nearing the end of their moult and many adults will start migrating just before the innermost secondaries are fully grown. Either way I have caught a lot more adults this July than usual and multiple factors may be involved. As I said in my previous post it will be interesting to see how the 2017 CES results and other surveys compare.

 

Adult Willow Warbler showing more extensive yellow across the belly and a relatively pointed tail. This bird didn't shout adult and is the sort of bird that can trip you up if you're not careful and rely too heavily on a particular feature such as the colour of the underparts. Careful examination revealed it was still in active wing moult, but only just, as can be seen in the image below. 

Primary moult was just about complete but the big give away was the inner 2 secondaries that stand out as being that bit shorter than the longest tertial. Examination from underneath showed the inner 3 had some feather sheath at their bases. It is always worth giving those inner secondaries a look as the moult usually finishes with the innermost secondary rather than the outer primaries. 

I don't operate a standardised mist-netting regime so that has to be borne in mind when looking at the figures, ringing effort, however, was reasonably consistent so I still thought the figures were worth sharing. Willow Warblers are declining across the UK with the exception of Scotland and I am lucky to have a site that still has quite a good breeding population and also attracts good numbers of passage migrants (especially for an inland site). In 2016 a total of 367 Willow Warblers were ringed at the site which, like the 2016 July totals, was significantly up on the previous 2 years (2015/256 & 2014/240) so it will be interesting to see what the total looks like at the end of this year.

Highlights amongst the other birds caught included the first Garden Warbler of the autumn. A Whitethroat was also a first for the autumn but an unusually late one at that, I don't catch many Whitethroats at the site but I've usually caught a few juveniles well before the end of the month. Goldcrest on the other hand appear to be having a good year with another 10 bringing the total for July to 19. This compares favourably with the July totals for previous years - 10 in 2016, 8 in 2015 and only 3 in 2014.

Combined ringing totals (retraps in brackets) for 28th to 31st July 2017 were: Goldcrest 10; Blue Tit 3; Great Tit 4; Chiffchaff 4(2); Willow Warbler 43(4); Blackcap 7(1); Garden Warbler 1, Whitethroat 1; Treecreeper 1; Wren 4; Song Thrush 1; Robin 2, Chaffinch 1; Bullfinch 2; Linnet 5; Goldfinch 2 (2); Reed Bunting.

Garden Warbler. A scarce passage migrant at the site with most records coming in late July and early August.

Whitethroat.  A few pairs breed at the site so I usually catch a few juveniles in July but not this year.

25th July 2017: What's happened to Willow Warblers

Another ringing session in the top willows at Billinge failed to produce the sorts of numbers expected for this site in late July. It was made even more disappointing by the fact that it was my earliest start of the autumn (I got up at 04:30) and the conditions were perfect for mist-netting all morning.

The calm and overcast conditions were perfect for mist-netting. Looking in this direction on a clear day I can normally see the major landmarks of Liverpool and the Welsh mountains beyond.

There were a few more Willow Warblers around with a total of 17 (12 new & 5 retraps) being an improvement on the previous visit but almost half (8) were adults which is really unusual. To put that into context I haven't caught anywhere near that many adults in a single July session before, and in 2016 only caught 7 adults in the whole of the month.

Adult Willow Warbler

You can't read too much into a single session so I looked at the ratio of juveniles to adults caught each July over the last 3 years. This is a better guide to productivity than overall numbers as it removes any effect caused by variation in ringing effort between years. The results showed that juveniles have outnumbered adults by a least 5:1 in each of the last 3 years, and in July 2016 the ratio was just shy of 17:1. The average of the ratios for the last 3 years being just over 10:1.

Willow Warblers: juvenile left and and adult right. The juvenile shows the typical lemon yellow washed underparts whereas the adult is much whiter although this adult has more extensive white underparts than many.

Looking at the figures for this July the ratio of juveniles to adults currently stands at just under 2.5:1 which is quite worrying and suggests productivity is well down compared to previous years. There is not much of July left so even if the weather allows me to get out again before the end of the month I would have to catch 43 juveniles and no adults just to bring the ratio up to 5:1 and there seems to be little likelihood of that happening. To bring the ratio near to the average of the last 3 years I would have to catch 133 juveniles and no adults and there is simply no prospect of that. It certainly looks like Willow Warblers have had a very poor breeding season, locally at least. I say locally as most of the birds caught in July will be local breeders and their offspring. 

The prospects for this breeding season had looked quite good at one stage with with migrants, like Willow Warblers, arriving quite early and in good numbers. There is no doubt the weather over the spring and summer has been mixed but it generally seemed to be more favourable for breeding birds than the last couple of years and certainly no worse. To find that Willow Warbler productivity appears to be so low this year is totally unexpected and hard to explain. It will be interesting to see the results of CES and other BTO surveys when they come out later in the year to see how they compare.

Willow Warblers have shown marked differences in regional trends in recent years with the species showing large declines in the south and holding their own or doing better further north. Next month should see a lot of migrant Willow Warblers move through the site and their numbers may give an indication as to how the species has fared in more northerly areas of England and Scotland. Lets hope they have done better further north.

The final capture total of 40 birds (33 new and 7 retraps) was less than expected and continues to suggest that quite a few species have had a poor breeding season locally. Ringing totals for 25/07/2016 (retraps in brackets) were: Goldcrest 2; Blue Tit 5; Great Tit 1; Willow Tit (1); Chichchaff 5 (1); Willow Warbler 12 (5); Blackcap 2; Wren 1; Robin 1; Chaffinch 1; Bullfinch 1; Goldfinch 1; Reed Bunting 1.

Billinge: 22nd 2017 July

I had high high hopes for this session in the top willows by my optimism and early start wasn't rewarded. Equivalent sessions in previous years have produced good numbers of phylloscs and out of habitat migrants such as Sedge and Reed Warblers but that wasn't repeated today. The weather probably played a part as overnight rain probably put the dampers on any migration and the site was still shrouded in hill fog/low cloud when I arrived, although it soon lifted.

It turned out to be one of those days that was noteworthy for the birds that were absent or only present in low numbers and chief amongst those was Chiffchaff with only 1 recorded all morning, and that one only turned shortly before I packed up. There were fewer Blackcaps around than usual and although Willow Warblers crept into double figures a total in the high teens would have been nearer the norm. Once again, tits were few and far between and there was certainly no sign of any mixed tit/warbler flock formation. I didn't even hear any Long-tailed Tits nearby or in the distance. The only species that seemed to be present in higher numbers than usual was Wren with 5 ringed. I think Wrens should be renamed fidget spinners as this aptly describes their behaviour in a mist-net.

The final total of 32 new birds and 4 retraps wasn't bad but was lower than expected for late July. Totals for 22/07/17 (retraps in brackets) were: Great Tit 2; Willow Tit (1); Blue Tit 2; Chiffchaff 1; Willow Warbler 11 (1); Blackcap 3 (1); Treecreeper 1; Wren 5;  Robin 1; Bullfinch 3 (1); Goldfinch 2; Reed Bunting 1.

Adult Willow Warbler (all the photos below are of the same bird).
Three of the Willow Warblers were adults and two of them had almost completed their full moult.

Once the moult is completed, in probably just a few days for this individual, they start migrating back to Africa. They often start to put on fat just prior to the completion of the moult so they are ready to go with little or no delay.

Once the moult is completed Willow Warblers can only be aged by the colour of the underparts and shape and wear of the tail feathers. Adults have a white belly whereas juveniles are usually completely yellow or yellowish underneath.

Adult tail. Generally broader and less pointed and also showing less wear than the juvenile tail. The tail feathers are usually glossier too as they are newer than those of most juveniles which often look a tad browner.

Billinge: 17th & 18th July 2017

17th July
I am not getting any better at the early morning lark and only got to site at 7am. The weather was glorious and it was very warm from the off. I quickly set 3 nets in the top willows but there was distinct lack of warblers calling in the bushes which suggested there were fewer around compared to my last visit. On the other hand there had been a marked increase in the number of Goldfinches with at least 60 feeding on the knapweed in the vicinity of the net rides.

A total of 46 new birds were caught with all but one being juveniles. The single adult was a moulting female Willow Warbler. The ringing totals confirmed that there were fewer warblers around but this was offset by a good catch of Goldfinches. The biggest surprise was a near total absence of tits, not that I am complaining, with only 2 caught and hardly any others seen or heard.

Juvenile Goldfinch

One of the juvenile Goldfinches had white sub-terminal patches on the three outer tail feathers. These patches were once thought to have some age related significance and while the number of patches Goldfinches have varies between 1 and 3 the presence of 3 was considered to be something that was only found in some adults. Juveniles like the bird above clearly show that can't be the case and serve as a useful reminder. A more recent study suggested birds with 3 patches were always males and while males may have more and or bigger patches on average there is more overlap than that study found and I have caught females with 3. I am sure these tail patches have an important role as birds spread their tail and show them off when they do the clockwork like pivoting display but they are not the help we would like them to be when it comes to ageing and sexing Goldfinches in the hand.

Totals for 17/07/17 were: Goldcrest 1; Great Tit 1; Coal Tit 1; Chiffchaff 6; Willow Warbler 7; Blackcap 6; Wren 3;  Greenfinch 1; Goldfinch 20.


18th July
With thundery and then showery conditions forecast from mid-week I decided to fit in another visit and try the rides in the NE corner of the site. It was another very warm morning and the biting insects were really on form but it turned out to be very quiet on the bird front. The catching rate was really slow and I packed up at 10am, following 2 blank net rounds, and having only caught a total of 14 new birds in the earlier rounds.

Again there were hardly any tits around and warblers were also very thin on the ground for this part of the site. Tits are supposed to have had a reasonable breeding season but I haven't seen or heard any sizeable tit flocks as yet but that doesn't mean they are not out there, somewhere. It was just one of those mornings that produced a below par catch, as happens now again, and it will be a while before we really know what sort of breeding season it has been overall.

One of the Dunnocks was a recently fledged juvenile.

The flight feathers were not fully grown but it could fly quite well and was caught in the top panel of a mist net.

It will still be dependant on its parents for food so it was released very close to where it was caught.

Overhead there was no movement to speak of but a single Yellow Wagtail, a scarce bird in this area these days, went south as did a Siskin.

Ringing totals for 18/07/17 were: Goldcrest 3; Blue Tit 1; Chiffchaff 2; Willow Warbler 1; Blackcap 1; Wren 2;  Dunnock 2; Chaffinch 1; Bullfinch 1.

12th July 2017 - A bunch of Blackcaps

I only managed a 06:30 start at in the top willows at Billinge but I don't think I missed much as a result, at least I hope not. I set three 18m nets under clear blue skies and with only a light breeze blowing from the NE. The catching rate was better than expected for this early in the month and suggests it has been a fairly productive breeding season, especially when compared with the last couple of years. I packed up at 11:00 as the sun was shining on all the nets by then, making them much more visible, and before it got too hot.

The final total of 44 new birds and 2 retraps was mainly comprised of juveniles and included 32 warblers, 17 of which were Blackcaps. The two retraps were an adult male Blackcap that was originally ringed as a juvenile in July 2015 and a juvenile Blackcap that was ringed just over a week ago. The Blackcaps were mainly feeding on raspberries that grow wild near one of the net rides and most of them were caught in that particular net. This raspberry patch usually attracts and holds a good number of locally bred juveniles in July although 17 is more than I usually catch in one session.

Juvenile Blackcap

Juvenile Willow Tit.
Late June and July is the peak period for juvenile dispersal in this species and this is the 3rd to be ringed at the site in the last week.

Juvenile Treecreeper
July is also a time when the young of woodland species disperse and can be encountered well away from their usual habitat. 

There was some interest overhead with the highlight being a Crossbill that called loudly as it flew SW. A Siskin was also heard but not seen and a few Swallows seemed to be heading south. I wasn't in the best place to observe the Swallow movement but small groups appeared to motoring south from time to time; they certainly weren't the feeding flights of the local breeders.

Ringing totals for 12/07/17 (retraps in brackets) were: Blue Tit 2; Great Tit 2; Willow Tit 1; Goldcrest 1; Chiffchaff 5; Willow Warbler 10; Blackcap 15 (2); Treecreeper 1; Wren 1; Goldfinch 6.