gnsadmin

Visit 12 on 28/08/2018

The last visit of the survey. All twelve visits completed this year, and a good range of species caught. Full details to follow in the annual report.

Like the last visit this one was a small catch, reflecting the trend of recent years for catches to fall off during August. The catch of 31 birds was below average and was the third equal lowest catch. Despite this, the total for the year will put 2018 in the middle of the “league table” of catches, so in terms of overall numbers it has been an average year. The full report will show how the different species have done.

Of the 31 birds caught today, 19 were of resident species, the first time that resident birds have outnumbered summer migrants. All the Sedge warblers had gone, and only two Whitethroat were caught. Solitary Willow warbler and Redstart, two blackcaps, and a few more low flying Swallows made up the migrant catch.

With the end of the CES season, we now have a little break, then re-commence ringing here at Ashleworth towards the end of September to monitor the Autumn passage of Reed Buntings and Meadow Pipits. These will hopefully be joined by flocks of Finches.

Most people will think of Upham Meadow at Twyning as a Lammas Meadow, one of the traditional Severn and Avon Vale riverside meadows, which floods in winter and produces a hay crop in summer.  It is a Site of Special Scientific Interest because of its nesting hay meadow birds – in particular Curlews, Redshanks, until recently Corn Buntings, with Reed  and Sedge Warblers round the edges, and many pairs of Reed Buntings. It’s also well known for its hay meadow botany, and is particularly rich in species like Meadowsweet and Great Burnet, as well as two species of Water Dropwort, the Narrow-leaved and the Tubular. This natural diversity is maintained by traditional farming practices: no fertiliser (the river floods bring enough of that); no spraying (which means that Ragwort is a problem); hay cutting beginning on 15 June and proceeding strip by strip until Lammas Day  in early August; prohibited access in the summer months; then aftermath grazing by commoners who have grazing rights. The whole system is overseen by the Haywarden, one of the owners of the strips of land. This system is supported by current agri-environmental schemes, managed by Natural England.

In autumn and winter, before the floods rise, the site is grazed by sheep and cattle. Among the species present are large numbers of Canada Geese, and in recent winters some of these birds have proved to be carrying engraved colour rings, which were put on in midsummer, of all places at Windermere.  The birds go there during the moult period, when they are flightless, and need to keep well out of the way of marauders. Having renewed their flight feathers, they make for the Severn and Avon Vales to winter. One of these Canada Geese was marked at Bowness in Windermere in July 2013, with a red ring bearing the inscription AASK in white letters. I have since seen this same bird with the same ring, at Upham Meadow in November and December 2014, February, October and December 2015 and in November 2016; I didn’t manage to find it in winter 2017/18, so was pleased to observe it again on 17 November 2018, back in familiar surroundings. It is clearly very faithful to this site.

While I was pleased to see Canada AASK again, a much more surprising find was a Greenland White-fronted Goose Anser albifrons flavirostris, among a flock of just over a hundred Canada Geese. The Greenland Whitefront is the subspecies of Whitefront that nests in Greenland, and passes through Iceland to winter in Ireland and western Scotland; it was first named by Sir Peter Scott who named it for its yellow bill (‘flavirostiris’), yellow legs and heavier barring on the belly. It is fairly unusual in Gloucestershire – The “Birds of Gloucestershire” indicates that it has occurred, mainly at Slimbridge, in about 20 winters since 1945, generally birds which overshot Ireland on their way southeast. This subspecies is relatively easy to distinguish from the European Whitefront Anser albifrons albifrons which breeds in Russia and migrates through western Europe, reaching Slimbridge as its most westerly wintering site.

When I looked more closely at the bird – even more exciting –  I found it had a satellite transmitter round its neck, so (if the transmitter was working) there was a chance of finding out more about the route it had taken to reach Twyning. The bird was seen a bit later on the Worcestershire bank near Fleet Lane by Andy Warr who took the attached pictures, which clearly show the transmitter, and the yellow bill. It has been seen since then in several sites on the Worcestershire border, at least until 20 November.

I sent this information to goose expert Dr Tony Fox, once of Slimbridge, now working in Denmark as a key figure in international goose studies, and for many years a specialist in Greenland Whitefront. His response was as follows:

“This bird was indeed an adult female Greenland White-fronted Goose caught in Hvanneyri, West Iceland, on 23 September 2017; after several days at Hvanneyri, she shifted westwards within Iceland to spend the remaining time staging in Myrar. That autumn she overshot Wexford (literally overflying County Waterford), hit the Brittany coast and looped round back over Cornwall to arrive finally at Wexford, where she wintered.

“In autumn of 2018, she left Iceland on 24 October sometime after 14:37 UTC and was mid-way across the sea at 02:00 on 25 October, but was clearly drifting very far east, ending up in mid North Sea, arriving off Texel at 17:00.  She clipped Goeree, south of Rotterdam, at 20:00, and a little later left the Belgian coast off Zeebrugge, reaching the English coast at 00:30 on 26 October at the mouth of the Deben Estuary. She looped southwest and departed the southern English coast between Newhaven and Seaford, heading for the French coast, which she reached at about 07:00 same day, just north of Le Havre. Clearly not satisfied with her landfall, she headed NE and just inland of Calais and at around 12:00 swung NW and crossed the Channel again, coming into NE Kent in mid-afternoon on 26 October.  She headed for the north coast and seemed to rest on the sea (the first time she seems to have rested since leaving Iceland) between 19:00-21:00 between Birchington-on-Sea and Herne Bay.  She seemed to land in a field just inland from there, but at midnight set off west, following the north coast of Kent, continuing over south London (just south of Heathrow at 15:00 on 27 October).  She stopped briefly for a few hours from 19:00-21:00 in fields near Aynho, at the southern end of Northamptonshire before heading on, and probably roosted in north Gloucestershire before heading onwards. By 17:50 on 28 October she reached gravel pits at Great Comberton and has been on the Gloucestershire/Worcestershire border ever since.

The map below shows her itinerary, as revealed by the satellite. This all shows that Upham Meadow is interesting not just for Curlews and Water-Dropwort!

STOP PRESS: Latest news of the Greenland Whitefront: the transmitter suddenly stopped working overnight on 20 November, when the bird was known to be roosting at Kemerton Lake in south Worcestershire.  It was feared that the bird had been predated, perhaps by a fox? Careful searches of the site revealed no corpse and no transmitter, and searches for the bird among flocks of Canada Geese were also unsuccessful. Fortunately, however, it turned out that the fears were groundless: the transmitter started working again (sending a signal every 15 minutes), and in the last few days of November, she has visited Ripple Lake and Longdon Marsh in Worcestershire, and Tirley and Coombe Hill in Gloucestershire. Incidentally, while the neck collars may look ugly and cumbersome, Tiny Fox comments: “We started by using backpacks back in the 1990s, but had huge problems with geese ripping out the antennae and chewing through harnesses.  There have been some published analyses of using different types of attachment on geese, and the prevailing wisdom is that collar mounted devices are by far the best for the survival and fitness of the birds.”

Mike Smart

Ringing at Ashleworth Ham

Visit 11 on 21 August 2018

The conditions for catching birds were perfect, slightly overcast, and only a light breeze. The trouble is that, in order to catch birds, there need to be birds present. The complete absence of bird sound whilst putting up the nets, soon materialised into the second lowest catch of the year. Whilst not totally unexpected, it is always disappointing to have fears confirmed. The catch of 30 birds was well below the averages (48 for last five years, and 52 for the full twenty previous years). The hedgerows are full of fruit, and a few insects are around, but for the time being, the birds appear to have left the site, a feature that has been noted in previous years. Numbers pick up again in mid- to late September, and good catches are obtained in October.

Whitethroat topped the list with six birds caught, closely followed by Blackcap and Redstart with five of each species. All five Blackcaps were re-traps, of which two were adults in full annual moult. Two each of Redstart and Whitethroat were re-traps, one of the Whitethroats being an adult in annual moult.

The Redstarts were all juveniles at different stages of their post juvenile moult. Two were females fully moulted out, but still recognisable as juveniles by the orange fringes on the greater coverts, the other three were males, one obviously so as it was nearly through its moult, the other two were only just recognisable as males, as their moult had just reached their heads, and a few white feathers were just beginning to show through their protective sheaths. It is this opportunity to see these intimate details of a bird’s life cycle, that is one of the major appeals of ringing. For the scientists studying populations, the data from Ashleworth show that in this area, Redstarts have had a successful breeding season, with 22 of the 31 individuals handled this year being juveniles.

Chiffchaffs on the other hand appear not to have done so well locally.  Most years at this time, the sound we hear most frequently is the disyllabic call note of the young birds keeping contact with each other. This year there is little or no sound of them, and the catching figures reflect this, each visit yielding an average of just over one bird per visit, compared with last year when each visit yielded 8.4 birds per visit, and 5.8 birds per visit in 2016. It will be interesting to see if visit 12 (the final CES visit) does anything to change these statistics, but it is doubtful if it will.

Mervyn Greening

Ringing at Hasfield Ham

by Mervyn Greening

Visit 10 on Tuesday 14 August 2018

The electric fence, to protect the netting area from cattle, was re-instated yesterday, and was still standing when operations started this morning. Weather-wise, the conditions could not have been better, slightly overcast and with the gentlest of breezes. Whilst the nets were being erected it was noted that there was virtually no bird sound. So, despite the perfect conditions, it was no surprise that catching was very slow.

.

If it hadn’t been for the arrival of good numbers of migrating Swallows and House Martins, some of which descended low enough to be caught, the catch would have been well below the average of 57. As it was the catch, with the hirundines, was slightly above average at 63. Of the regular birds, Whitethroat was top of the list with nine caught, followed by Bullfinches with six.

.

.

Of the 63 birds caught, only five were adults, four of which were in post-breeding moult, while one had completed its moult. All the hirundines were birds of the year which had completed their rapid, short, and incomplete post-juvenile moult, which will be finished when they reach their winter quarters. Young Swallows look like adults, but with much subdued colours, especially the throat which is rusty rather than red. House Martin juveniles on the other hand look quite different from the adults. Their plumage is more the colour of Sand Martins, as the blue tinge to the black feathers is not developed until post-juvenile plumage. When the birds are in the hand, and the rump (which is white) and the underparts are not readily visible, then the head alone could easily be mistaken for a Sand Martin.

.

During the morning the cattle paid us a visit, and the effectiveness of a fully operational electric fence was demonstrated, when the herd tried to walk through the hedge where the nets are, only for the leading cows to touch the fence and jump back; this in turn caused confusion for the cows behind which ran off. Question now is, do the others learn from the ones in front? Or do they all have to touch the fence at some time to know what it does?

.

One of the interesting things for me at this time of year is seeing young birds at different stages of post-juvenile (PJ) moult. A multi-brooded species like the Robin, can have young ranging from birds still completely in juvenile plumage, up to birds of the year that have completed their PJ moult and look exactly like adults. It’s also interesting to see the difference in the speed at which PJ moult happens. Long distance migrants like Swallows have a rapid and incomplete PJ moult; Chiffchaffs and Willow Warblers have a partial PJ moult of all their body feathers (but not flight feathers) which takes a few weeks; Wrens which have a similar strategy, stay in juvenile plumage a long time, then have a rapid moult; and Long-tailed Tits have a complete moult so are indistinguishable from adults by September.

.

.

Not all birds are healthy, and sometimes individuals are caught which cannot be ringed. Bullfinches and Chaffinches sometimes have mite infestations that cause their legs to develop growths. Such was the case with one of the adult Bullfinches caught today. In this male bird, the infestation has made the legs and claws grow unevenly and bigger.