Bilinge 9th July 2017 - more Swallows

I had planned an early morning ringing session in the top willows but I just couldn't motivate myself when the alarm went off, despite the weather conditions being near perfect. I decided some extra sleep was the order of the day; a decision that was made much easier because I knew I had the option of going up in the evening instead. I suppose I could, and perhaps should, have done both but I will save that kind of effort for later in the season.

I went to site at 7pm and quickly set 2 nets in the willows. I could hear a few warblers calling in the bushes as I was setting up but one thing that was absent was any sizeable tit flocks, not that I am complaining, although I did hear some Long-tailed Tits in the distance later on. There were quite few Swallows hawking insects overhead so I was hopeful that some would come into roost again and thankfully they did.

Part of the Swallow catch. I don't know why this site usually gets an early Swallow roost but it does, although numbers and duration of occupancy of the roost have varied from year to year. However, its future may be limited by the growth of the trees as the birds seem to prefer to roost in willows that average about 1.5 to 2 metres tall and some are more than twice that height now.

Juvenile Swallow

Adult male Swallow showing a fine pair of tail streamers.

The total of 41 new birds and 1 retrap was a good result with the majority of the catch being made up of Swallows and warblers. The individual totals (retraps in brackets) were: Blue Tit 1; Willow Tit 1; Swallow 23; Chiffchaff 4; Willow Warbler 3 (1); Blackcap 5; Blackbird 1; Goldfinch 2, Reed Bunting 1.

Observations of note were a Noctule Bat, surprisingly the first I have seen over the site, and as I was leaving I could hear a Grasshopper Warbler reeling from the territory in NE corner.

Billinge: 4th & 7th July 2017

4th July
This was a dual purpose evening visit to do a bit of ringing and work on clearing some of the summer's growth from one of the net rides in the top willows. I didn't get to site as early as I had originally planned so I only put up one 18m net rather than two as intended but that didn't matter as there was plenty of pruning to do.

The single net produced a trickle of birds which left me enough time to get another net ride cleared and ready for the rest of the autumn. As sunset approached I started to think about packing up but then some Swallows appeared so I stayed until they came into roost and I ended up catching 25 of them. The final ringing totals (retraps in brackets) were: Blue Tit 1; Swallow 25; Chiffchaff 2 (1); Willow Warbler 4 (2); Blackcap 2; Goldfinch 1. Total 35 new birds and 3 retraps.

7th July
I only got up after the 3rd alarm and some snoozing so not the early start that I had intended. I set 3 nets in the NE corner of the site and was set up by 06:40. Two Grasshopper Warblers were reeling nearby with one being in the same area as a bird recorded in early May but the other was singing in a less expected location and was reeling in the adjacent field of barley.

The catching rate was slow to start with but improved as the morning went on, although it didn't get busy. Highlights were 2 juvenile and an adult Grasshopper Warbler with the adult being a retrap male that was originally ringed on 2nd May this year. This strongly suggest they have bred successfully and constitutes the first breeding record for the site, although a bird held a territory last year and may have bred. The rest of the catch was fairly typical for this part of the site at this time of year and included the first juvenile Goldcrests and a juvenile Willow Tit.

Juvenile Grasshopper Warbler

Juvenile Grasshopper Warbler,

The two juvenile Grasshopper Warblers showed some of the variation in colour this species can display with one having mainly white underparts and the other having buff coloured underparts.

Juvenile Goldcrests always look scruffy as they go through their post-juvenile moult

This bird was just starting to show orange feathers (encased in sheath) growing in the crown which meant it could be sexed as a male. 

Juvenile Willow Tit.

Another feature of the site at this time of year are frequent encounters horse-flies and clegs and I donated far too much blood to their kind during the session. Luckily I haven't had any adverse reactions but these insects will continue to be a pain in the neck or other parts of the body during visits over the next few weeks.

There was a little bit of movement overhead with 1 Siskin heading south and 3 singles heading north and a Grey Wagtail heading south was particularly early for that species to be on the move.

Ringing totals for the 7th were: Goldcrest 2; Blue Tit 5; Great Tit 4; Coal Tit 1; Willow Tit 1; Chiffchaff 7; Willow Warbler 2; Blackcap 1; Grashopper Warbler 2 (1); Wren 1; Robin 1; Bullfinch (1). Total 27 new birds and 2 retraps.

Cropper and Gropper

Just when I thought I would have more time to post on the blog my 96 year old mother has a fall while stepping up a kerb and comes an almighty cropper, as she would say. Old ladies tend not to bounce very well, and my mother was no exception, but at least she didn't break anything. She was very lucky to get away with a few grazes and some bruising but needs more help and support while she recovers and gets her mobility back. Suffice to say I have not had much time for ringing or posting on the blog and what spare time has been available has been devoted to recording colour-ringed Starlings in the garden for my RAS project.

Anyway I did manage to fit in a short ringing session at Billinge yesterday morning and while it only produced 3 birds it was good to be out. The highlight was a singing Grasshopper Warbler which was my first of the year. It was caught and ringed and resumed singing almost immediately on release. It may have been a passage migrant that was holding a temporary territory but there is just enough suitable habitat for the species to breed should it stay and attract a mate. It is certainly something I will be keeping an eye on when time allows.

Grasshopper Warbler 02/05/2017

Grasshopper Warbler 02/05/2017

The only other birds caught were 2 Willow Warblers, both females. One was a new bird but the other was a retrap that was originally ringed as a first-year bird in August 2015 and was also retrapped as a breeding adult in 2016. Whilst male Willow Warblers have been back on territory for a while now females are still arriving and the new bird was relatively light and showed no signs of being in breeding condition. The retrap was probably a recent arrival too as it was only in the very early stages of developing a brood patch. The only visible migration of note was a single fly-over Tree Pipit which was much less than expected but welcome nevertheless.

As things stand I am unlikely to be able to get out as much as I would like in the near future but a few recoveries have been coming in and there is also the Starling RAS to report on so I will have something to blog about fairly soon or at least when other commitments allow. As the saying goes, if it is not one thing, it's your mother.

Robin Day

After the overcast and murky conditions of the past few days it was good to see the sun rise at the Billinge site this morning. I had three nets up at first light and set MP3 lures playing Meadow Pipit and Grey Wagtail under one of them. I thought the clear conditions may see an increase in visible migration but it soon became apparent that there was very little on the move. Perhaps it was the near flat calm conditions that was responsible for the lack of movement but the sky was largely devoid of migrating birds and Meadow Pipits in particular.

The nets revealed that there were more birds in the bushes than I had initially thought. The first net round produced 3 Robin, 7 Goldcrest, a Chiffchaff and a Grasshopper Warbler. More Robins were caught in nearly every net round with most of them being caught in the same net. By the time I had packed up at 10:45 I had ringed 13 which is an exceptional number for the location. This brings the total ringed at the site over the past 4 weeks to 40 and there seems to be many more Robins moving this autumn than is usual. Most species have had an excellent breeding season this year and these Robins are likely to be displaced British birds that are moving to find a territory rather than continental migrants. It will be interesting to see how many more pass through the site over the rest of the autumn and of course it would be great if one is recovered or controlled elsewhere.

Grasshopper Warbler (Locustella naevia)

Robin (Erithacus rubecula)

Ringing totals with retraps in brackets:
Robin 13
Goldcrest 19
Chiffchaff 12 (1)
Grasshopper Warbler 1
Blackcap 1
Grey Wagtail 1
Meadow Pipit 5
Yellowhammer 1
Chaffinch 1
Dunnock 1
Total 55 (+1 retrap)

Mystery Grasshopper Warbler remains so.

The unusual pale olive-grey Grasshopper Warbler caught on 25/04/14 (previous post can be found here) remains just that an unusual pale olive-grey Grasshopper Warbler. Much trawling of the internet and searching through various reference works and publications hasn't really thrown much light on the matter. I now know a lot more about Grasshopper Warblers but not much more about this particular bird. It still seems to be a potential toss-up between eastern sub-species and plumage aberration or rare colour morph. Whatever it is I haven't come across a comparable photograph including those of the eastern sub-species, straminea. However, some illustrations of straminea show spring birds can be greyish but seemingly not quite as pale as this particular bird.

Below are a couple of images of more typical olive-brown Grasshopper Warblers that were caught in the following days.

To try and progress matters I emailed Martin Garner to see if he had come across anything similar or to see if he could suggest any lines of enquiry. He agreed it was an interesting bird and requested some images for the Birding Frontiers website (link here) which focuses on identification issues and has a much better reach than my blog. Hopefully having some images published on that site may spark some suggestions but we still have to accept that we may never really know what it is in the absence of DNA testing. Whatever the outcome I still plan to submit it informally to the British Birds Rarities Committee (BBRC) for their consideration and for reference. If a bird like this can turn up once then it can turn up again.

One of the things I came across when researching via the net was a paper (link here) reviewing claims of Eastern Grasshopper Warblers in Britain (Harvey & Small 2007). This paper reported that the 4th primary was slightly emarginated in just over 50% of a sample of 20 of the eastern subspecies straminea and that this feather wasn't emarginated in any of the 12 nominate birds (naevia) examined. However one of the nominate birds I caught on the same day as the pale bird showed a slight emargination on the 4th primary. 

I had only photographed this bird's wing because it had clearly gone through some kind of eccentric moult and had replaced a number of primaries in both wings. These new feathers also stood out as they appeared longer than they should be relative to the old feathers either side. I only noticed the slight emargination of the 4th primary when comparing photographs of various Grasshopper Warblers subsequently. Although the emargination on the 4th is only slight it is clearly there, especially when the feather is compared with the 5th, and would be recorded as such for the wing formula of this bird. The presence of a slight emargination of the 4th primary may not be the potential indicator of a bird worth further examination as that paper suggests and perhaps more importantly shows how much we still have to learn about Grasshopper Warblers.

What a Gropper.

I have to admit to getting caught out yesterday and it was not by the weather. No, it was by an olive grey Grasshopper Warbler that made some very unusual noises to boot. This bird was striking, very very striking and it was clearly a Grasshopper Warbler of sorts but it was not on Fair Isle, North Ronaldsay or the East coast of England, no it was in Wigan.

pale olive-grey looking Grasshopper Warbler ringed 25/04/13

Now if it doesn't seem that pale to you lets have a look at a more typical warm brown Gropper.

Grasshopper Warbler ringed 20/04/14.

The only reference I had with me was Svensson, the ringers bible, and having checked all the specific features I was satisfied that it was a Grasshopper Warbler but given its pale appearance there was clearly a chance it was one of the eastern subspecies. The main contenders are straminea from Eastern Russia, Western Siberia and Central Asia and obscurior from the North Caucasus.

Now where I was caught out is that I now know that it would have been useful to take more measurements than I actually did and especially of the tail. A bit of a cock-up with hindsight but then there is so much overlap between the subspecies they may not have helped anyway. The wing length of 64mm means it wasn't particularly small but it could still be OK for straminea, just. At the time I was more concerned about confirming that it was actually a Grasshopper Warbler as it looked so different. However, I did take a good series of photographs as I thought it may be identifiable as to the subspecies on its appearance alone.

Further enquiries are currently being made to see if it can be attributed to one of the eastern subspecies although we may only be able to say that it showed some characters of an 'Eastern type' Grasshopper Warbler. Unfortunately it didn't drop a feather so taking the DNA route isn't an option. A remarkable bird whichever way you look at it and one that seems likely to spark quite a bit of debate over its appearance and origin although it may well remain a mystery bird. I will keep you posted when I get some feedback from my enquiries.