29 November 2013

Crossbill, Avocet or Wrybill?

Beak deformities in wild birds are unusual, with fewer than one in 200 adult birds thought to be affected. As long as the bird can feed and preen once a bill is deformed enough that the tip isn't constantly worn away, it can grow to amazing lengths.

Juvenile Blue Tit with the a bill deformity. Ipsley Alders Nature Reserve, Mike Barstow

Whilst ringing at Ipsley Alders Nature Reserve, Redditch, Mike Barstow retrapped a Blue Tit on 25/11/2013 that he previously ringed on 19/01/2012 with no deformity noted. This bird now had a severely deformed bill (below). The bird appeared healthy with good plumage, muscle and even had a trace of fat. There are therefore two birds (above and below) that have been recorded at this site which have developed a beak deformity within a few years.The research continues.

Adult Blue Tit. Ipsley Alders Nature Reserve, Mike Barstow

Measuring bill length to investigate growth rate for future captures- Mike Barstow

 Types of beak deformities in the wild:
  • Crossed mandibles: similar to that of a Common Crossbill perhaps caused by slight asymmetry of the jaw. Straight beaks have been recorded as a deformity in Crossbills.
  • Decurved upper mandible: can occur when the tip of the lower mandible is damaged so that the beak does not close correctly.
  • Upcurved lower mandible: may occur when the tip of the upper mandible is missing (i.e. broken off).
  • Elongation of both mandibles: produces ‘Curlew-type’ beaks, although the degree of curvature varies considerably between individuals.
  • Bent to the side: seemingly uncommon, with one or other mandible warping sideways.
  • Gapped: where the upper and lower mandibles do not close fully leaving a visible gap.
For more information click here

20 November 2013

Wandering Caspian Gulls

We don't have many recoveries of Caspian Gulls and the ones we do get are colour-ring sightings of foreign-ringed birds: most are from Poland (62), with smaller numbers from Ukraine (8) and singles from Germany and Switzerland. But we have only recently started seeing reports from abroad of British-ringed Caspian Gulls and these have all involved birds ringed by the North Thames Gull Group at either Pitsea Tip (Essex) or Rainham Tip (London). A young bird ringed in December 2011 spent most of spring 2012 on Texel (The Netherlands) and another young bird ringed in October 2011 was seen at Blaringham (France) and Neeltje Jans (The Netherlands) over the rest of that winter and then on and off until March 2013. But perhaps the most interesting is GG61181 (Orange PR6T); ringed as a second-winter bird at Pitsea Tip in February 2010.

GG61181 at Pitsea in February 2010

PR6T was then seen in Germany in December 2011 and this east-west migration of Caspian Gulls seems to be the norm. True to form PR6T was then recently seen again, but this time in The Netherlands, on Terschelling Island on 18th November.

GG61181 in The Netherlands last week

Once again this highlights the kind of information that can be gained from colour-ringing studies, all of which rely on the support of the wider birding community in looking for and reporting these birds. Full details for this bird (and further photos) can be found on the North Thames Gull Group website, where you can also report any NTGG birds seen. Thanks to Paul Roper from the group for passing on this story and for the photos of he bird in the hand, and to Jacob de Vries for the photo of the bird in The Netherlands.

12 November 2013

A Mediterranean beach

Allan Hale writes:
"I have been reading Mediterranean Gull rings on the beach at Great Yarmouth since 1999. Of late a group of us have been taking the project much more seriously and we try to make a monthly visit during the period from late summer until the end of winter.

Since the 2009-10 winter we have identified 58 different Mediterranean Gulls that were ringed in 10 different countries.  They have originated from Belgium (32), Germany (12), France (3), Poland (3), U.K. (2), The Netherlands (2), Denmark (1), Czech Republic (1), Hungary (1) and Serbia (1).  There have been multiple sightings of many of these gulls.  Many valuable life histories have been identified, with some of the birds mentioned above also visiting Spain, Portugal and The Azores.

Mediterranean Gull - Dawn Balmer

Mediterranean Gulls have been shown to reach a ripe old age. Three of the birds we have seen this winter were originally ringed in 2001, one of them already 3 years old when ringed. We are anxiously looking out for another which was ringed back in 1999 and last seen at Great Yarmouth during late 2012.

Reading colour-rings has been a rewarding experience. Many onlookers have shown an interest in what we have been doing and have been amazed at the results."

Lee Barber writes:
"Even with all the data collected of colour ringed birds, there are still quite a few unringed birds that visit the site, that we know nothing about. Allan decided to take this project to another level and with the help of Jez Blackburn and his Cannon Netting skills and the kind permission of Seafront Enforcement and Facilities Officer, Keith Eglington, an attempt to catch and ring some of the unringed birds and to collect biometric data on the ones that already have rings was organised.

Now a scarce regular breeding bird, about 20 chicks are ringed every year and the annual total for adult Med Gulls for the last nine years vary from none to eight. These birds can be very wary to anything unusual but hopes were high for a catch, even if it was just one bird (see online report).

Canon net firing - David Pelling

After a couple of canon net fires and 15 unringed and 3 ringed in Belgium Med Gulls were safe under the net, with a few Black-headed Gulls. They were then metal and colour ringed, aged, weighed and measured and then released. We were lucky to have a reasonably large catch and we were able to compare the different ages of birds (below). The second year bird has a light orange beak but more importantly has black wing tips.

Mediterranean Gull. First year bird left, second year bird middle, adult right - David Pelling
Hopefully as the winter goes on, more gulls will be ringed and add to our knowledge of the survival and movements of this species. Some birds visiting Great Yarmouth have been seen more than 200 times so the life histories of these birds is fascinating.

06 November 2013

First BTO Chiffchaff to Hungary

It's not every day we see recoveries of passerines in Hungary, as it's much more expected to see records of things like colour-ringed Mediterranean Gulls from there (almost 1000 to date!). In fact, there are just two records of BTO-ringed passerines found in Hungary and, unsurprisingly, both were Lesser Whitethroats. The other way round, the only Hungarian-ringed passerine found here was the equally exceptional record of a Sand Martin recaught by ringers in Lincolnshire in 2008.

So it was a pleasant surprise to hear of a BTO-ringed Chiffchaff caught in Hungary (at Hódmezővásárhely, Csongrád) on 2nd November, shown by the star on the map below. This bird had been ringed as a juvenile at Eskmeals, Cumbria, in July 2013, so was presumably still on southward migration when recaught: or perhaps displaced by the back end of 'St Jude'?

ADV129 when recaught recently in Hungary

Foreign finding and ringing locations of UK Chiffchaffs
It would seem more likely to find a British Chiffchaff so far east on spring migration, but oddly the only vaguely similar record concerns a Ukrainian-ringed bird killed by a cat in Peterhead, Grampian, in December 1987. This bird had been ringed two months earlier so who knows where it was going!

Thanks (and congratulations) to Erna Borbáth for the photos of the bird in Hungary.