Mid July to October 2016 – Where have I been hiding for the last three months?   Leave a comment

Readers of this blog may have wondered whether I had abandoned it completely, was spending the last three months abroad or just had nothing to write about.

For a while I did nothing for the blog because I had used up all my storage space and was reluctant to pay for more. I’ve now capitulated and paid up for the extra space, although I will be uploading lower resolution photos in the future.

The main reason I have not updated this blog is because I have been incredibly busy manning the ringing site at Durlston near Swanage. Since 17th July I have visited no fewer than 50 times. My near-daily schedule has been getting up about two hours before dawn, arriving a good hour before sunrise and getting the nets up and ready for when the birds start moving. We have had the most successful season ever, by mid October we had ringed nearly 4500 birds, far more than any previous year with at least a month of autumn migration still to go.

Much of the afternoons have taken up with uploading the data onto my PC and sending it off via our group secretary to the BTO, preparing for the next day and sometimes having a nap after an early start. Hence the lack of blog posts. I have also been uploading our daily ringing totals from Durlston to the migration website Trektellen http://www.trektellen.org/ Go to captures and then select Durlston RS, the daily and annual totals. Summaries and graphs of occurrence for each species can be found by navigating the site. I have also been doing the laborious job of loading the daily totals from past years onto Trektellen. I have completed 2013-15 and have just got 2011-12 to do.

This post deals solely with ringing in Dorset at our sites at Durlston, Lytchett Bay and Fleets Lane in Poole from mid July to mid October.

By far the largest number of birds ringed were the two species of Phylloscopus warbler, Willow Warbler (below in the photo) and Chiffchaff (above)Whilst superficially similar they do have a lot of characteristics that tell them apart. Chiffchaff is smaller overall, has shorter primary projection, darker legs, darker flanks, more rounded head, a less prominent supercillium, but the most conclusive features that can only be seen in hand are the length of the second to fourth primary and the presence (Chiff) or absence (Willow) of an emargination on the 6th primary.

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Although I said that Willow Warblers were larger than Chiffchaffs there is some overlap. Small female Willow Warblers (left) certainly overlap in wing length and weight with largest Chiffchaffs. The bird on the right is a large male Willow Warbler with a wing length of 70mm. Only a proportion of Willows can be sexed on wing length as there is overlap between the sexes. In both the Willows above the long primary projection (the projection of the primary feathers beyond the tips of the tertials) can easily be seen.

 

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The following graph taken from Trektellen shows the numbers of Willow Warblers ringed at Durlston (averaged out per hour of ringing activity). The gap from early May and late July is partly because we do little ringing at this season but also because the species no longer breeds at the site, the range having shifted north with climate change. A few migrants are seen in spring, but numbers are dwarfed by the huge influx that occurs in late July and early August. By early September only a few are seen with the odd straggler occuring into early October. In total 942 birds were ringed with a maximum of 212 on 5th August this is our best year ever at Durlston and is well in excess of the previous maximum of 626 in 2013.

chiff-2016-trek

Chiffchaffs show a different pattern, Again migrants/returning breeders are seen in spring but because the birds breed locally they continue to be recorded into mid May and in late July to late August (no ringing took place between 14th May and 17th July). At the time when the Willow Warbler migration is tailing off Chiff numbers rise rapidly reaching a peak in late September to early/mid October. 1382 have been ringed so far this year, a huge increase on the best ever year (2013 – where 875 were ringed) and more than triple what was ringed last year. This is partially due to ringer effort/availability but also undoubtedly points to a bumper year for the species.

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The third most ringed bird in 2016 has been Blackcap. The total of 796 doesn’t quite match the bumper year of 2014 when 860 were ringed but the season isn’t quite finished yet. After the post-juvenile moult, Blackcaps can easily be sexed by the eponymous black cap of the male and the brown cap of the female. This bird presents a conundrum but it is far more likely to be a male that is showing some female-type brown feathers than a female that has somehow grown some extra male-type feathers. The colour and structure of the brown crown feathers does not fit that of the juvenile plumage and I think the entire crown has been moulted.

This biggest surprise of the year has been the capture of 102 Grasshopper Warblers, compared to the annual average of 16 over the last five years. It is true that we have been getting to the site earlier to try to catch this crepuscular skulker before the sun is up but that can only be part of the story.

We have also had our best ever year for Meadow Pipits with 220 ringed to date (although that was mainly down to one very successful day where we ringed 126). We have yet to get a recovery on any of the Meadow Pipits ringed at Durlston but we hope this year’s batch will change all that. Some Meadow Pipits can be hard to age but this one is easy. The brown not blackish centres and the diffuse buffy borders of the greater coverts and the unmoulted white edged median coverts showing a small black tooth clearly show it is a first year bird.

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Common Whitethroats are regular breeders in the park and surrounding area and also occur as migrants. Young birds are easy to age due to their dark, rather than hazel coloured eyes.

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Another aging feature is the muddy brown rather than white on the outer tail feather plus a restricted pale area on the 5th (penultimate) tail feather. This first-year bird is unusual in that it has lost its left hand outer tail feather but not the right. The replacement has grown back as an adult type, clearly different from its first-year counterpart.

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Whitethroats show an interesting pattern of occurrence. As a common breeder in the park we ring quite a few in the spring (one trapped on 1st May was ringed as a juvenile in July 15 – an example of natal philopatry) and would probably continue to trap some in late May – mid July if we had been active during that period. The spike in late July/early August represents locally bred juveniles before the main migration gets underway in mid August. The migration tails off rapidly in early September.

 

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Now for some of the birds we ring less often. A first year Whinchat ….

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The species can easily be identified by the white bases to the outer tail feathers.

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Although quite a common migrant, they prefer more open ground. We have ringed just two Wheatears this year. Both were of the Greenland race leucorhoa which leaves its breeding grounds in Greenland and eastern Canada and makes a non-stop flight across the Atlantic to Europe before continuing on to its wintering grounds in Africa.

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Common Redstarts weren’t all that common with an about-average showing of 15 . All but one showed the brown (rather than grey) tipped greater coverts of a 1st year bird

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The grey head and black chin, still fringed with white tips (which will wear away by next spring) indicates that this is a male.

 

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Although common inland, especially in coniferous woodland, Coal Tits are very unusual in our ringing area and this is the only Coal Tit to be ringed there this year.

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Melodious Warblers occur as close Dorset as northern France but are still no more than scarce migrants to the county. This bird was trapped on the early date of 26th July and is only the second to be ringed in the Park. Although its wing length is comparable to that of a Willow warbler, it is much stouter, has a much broader based bill, a plain-looking face with a beady eye. The short primary projection helps distinguish it from the similar Icterine Warbler.

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The group has been called on to do two public ringing demonstrations in 2016, one at Durlston and one at Lytchett Bay. At Lytchett (above) we had a good turn out of both ringers and public with about half of the group arriving to help. L-R Tony Taylor, me, Kevin Lane, Claire Young, Mike Gould, John Dowling and newcomer to the group Kath Clay, group ringing secretary Bob Gifford is at the front sat down. Photo taken by Lytchett stalwart Shaun Robson who did all the public demonstrating.

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The weather has been quite good throughout the period concerned with little rain and without protracted periods of wind and this has helped boost our totals, However for the first two weeks of October the winds blew strongly from the east and brought exceptional numbers of Siberian birds to the eastern shores of the UK. Few filtered down to Dorset (with the exception of Yellow-browed Warblers – see below) but we did see an exceptional number of Ring Ouzels. Although they are a scarce breeder in the uplands of Britain, they occurred in such numbers that they must have been augmented by birds from Scandinavia or beyond. For several days the winds were too strong to ring at Durlston so I fell back to our more sheltered site at Fleets Lane in Poole where this Ring Ouzel was trapped. Another was trapped by Shaun and Bob at Lytchett Bay. Photo by Terry Elborn.

YBW DCP SB

Yellow-browed Warblers breed in the Siberian taiga zone as close as the Ural Mountains, but migrate to SE Asia to winter. Numbers have been increasing in Britain in recent years (and wintering has been proved in SW Iberia and in the Canaries) but 2016 has seen the biggest influx ever. Counts at single sites in Yorkshire have exceeded a hundred on a single day and the total in the UK must run to many thousands. Even as far south as Dorset records have been broken.

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Between 2004 and 2015 our group has ringed six Yellow-browed Warblers (3 of those in 2015) this year we have ringed twelve already. None of these has been retrapped indicating rapid onwards movement. It would be wonderful to get a recovery on one of these Siberian waifs and help elucidate where they are going and why some have taken up a new migration strategy and maybe country-wide the BTO will, but on numerical grounds the chances of any of our twelve birds being recovered is slim.

 

This article has discussed the various birds that we ring and their identification and aging/sexing characteristics. The timing and variation in migration year on year plus the ability to age and sex the birds concerned provides valuable ornithological data. However what we all hope for is that our birds will be trapped elsewhere by another ringer (controlled) or recovered by a member of the public.

Although this year has been good for the number and variety of birds ringed it has also provided us with many recoveries: those received in 2016 pertaining to Durlston are shown below. We have also got three more controls in the pipeline.

DCP = Durlston Country Park

Species Ringed Ringed at  Date recovered Where recovered
Goldcrest 08/11/2015 DCP 13/03/2016 Milton Abbas, Dorset cat
Chiffchaff 12/10/2014 DCP 25/03/2016 Longis Pond, Alderney, Channel Islands retrapped
Willow Warbler 02/09/2015 DCP 27/09/2015 Arneiros, Querenca, Faro, Portugal retrapped
Blackcap 25/09/2013 DCP 19/04/2016 Longis Pond, Alderney, Channel Islands retrapped
Blackcap 01/09/2014 DCP 17/04/2016 Chew Valley Lake,  Somerset retrapped
Reed Warbler 18/06/2016 Chew Valley Lake,  Somerset, 06/08/2016 DCP retrapped
Willow Warbler 06/08/2016 Billinge Hill, Merseyside, 14/08/2016 DCP retrapped
Pied Flycatcher 13/06/2015 Kentmere Hall Plantation, Cumbria, 18/08/2016 DCP retrapped
Whitethroat 17/07/2016 DCP 14/08/2016 Gravelly Marsh, Needs Ore, Hampshire retrapped
Blackcap 21/09/2016 DCP 24/09/2016 Brook Farm, Reculver, Kent retrapped

In addition there have been many recoveries/controls of birds ringed at Lytchett Bay including many Reed and Sedge Warblers that moved to France, as well as others that were recovered nearer to their ringing location.

Each recovery adds to the complex jigsaw that makes up the life history of our birds.

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