Update on Black-headed Gull and Common Tern ringing projects
30 June 2011 | Tim Ball
The 2011 breeding season
This year was very successful at Hosehill - about 60 birds were counted sitting in a rough shore-based check of the small island and a rough estimate of birds nesting on the large island and rafts adds about another 40 or 50 pairs making 100 - 110 pairs in total. Our two ringing visits on 4 and 11 June resulted in 122 birds being colour ringed with a further 30 small chicks just ringed with metal rings.
Following several years of persistent predation the number of Black-headed Gulls and Common Terns attempting to nest was small - just 6 pairs of gulls and about 12 pairs of Terns. Unfortunately once again the colony was predated fairly early in the nesting cycle and as a result the colony was deserted. So far in 3 years of trying we have managed to colour ring just 3 chicks here, 1 is known to have been predated and the others almost certainly were as well.
We were asked to colour ring the Black-headed Gull chicks at Lea Farm GP along with the Common Terns (see below) and this was carried out on 26 June. 39 gull chicks were present on the 2 rafts and all were colour ringed. One of the nesting adults here (2X53) is a bird that was ringed at Hosehill in 2009.
So far the project has resulted in over 1,500 records and 26 birds have been seen at 1 or more places more than 20 km away from where they hatched. We have had sightings in Eire, France, 3 Welsh counties and 11 different English counties. Several birds have been reported locally after records elsewhere - 2X15 is a good example:
|04 to 13/07/29
|Hosehill - after fledging
|28/05 to 09/06/10
|Hosehill - regular records during a visit in it's 1st summer
|Booterstown, County Dublin, Eire, 404km WNW
|26/04 to 28/06/11
|Hosehill - not known if made a breeding attempt
Local sightings in 2011
We have had another huge series of records locally this summer and as would be expected as more birds reach sexual maturity there has been a tendency for these birds to arrive earlier and stay longer than they did in 2010. 34 birds have been seen locally so far this summer - coincidently the same number as were seen in 2010 however several birds haven't returned and 5 birds returned for the first time this year. It has been possible to sex 10 birds by their mating activity, hopefully this number will increase over the years and may reveal different movement strategies between the sexes. Several birds have been seen at other local breeding sites during the summer but 2X53 is the only one known to have bred elsewhere.
Only 28 birds (24.1%) have returned in their first summer - this is noticeably less than the 34 (34%) of 2009 birds that returned in their first summer. There's still a little time left for this number to increase and it's too early to identify the reasons for the difference:
- is it just normal variation?
- was mortality in the 2010 cohort particularly high?
- have more 2010 birds lost their colour rings? - the darvic material used for the 2009 rings is no longer manufactured and a different plastic is now used.
The Hosehill birds are already fledging and sightings over the next few weeks will be an important measure of fledging success. The Lea Farm birds are at least 2 weeks later than most of the Hosehill birds and we are keen to encourage the local patch birders to start recording birds regularly - the site layout is pretty good for checking for colour rings and hopefully we'll soon start getting records of the birds before they disperse.
Sightings of birds ringed elsewhere
It's been a good summer for records of birds ringed elsewhere:
Yellow K084 was ringed as a chick in Saint-Petersburg, Russia on 10 June last year, it was seen at Dinton on 15 March and at Hosehill on 7 May and appears to have spending its first summer on or close to the place where it spent its first winter as some of our birds have done.
Yellow N176 was ringed as a 1st winter on 2 January this year in Salamanca, Spain and was seen at Hosehill on 11 May. It's conceivable it was a locally bred bird wintering in Iberia and is definitely one to look out for in future years.
White 2A98 is a female ringed as a chick in Cotswold Water Park in 2004 and has been a regular visitor to Hosehill since 2009 and has bred for at least the last 2 years.
White 2N27 was ringed as a chick at Slimbridge on 24 June last year and seen at Hosehill on 2 June this year. As we have found with our birds, occasional individuals travel east rather than west.
Some statistics from Hosehill
|Proved to have fledged
|65 (53.3%) $
|Seen locally during 1st summer (Mar-Jul)
|Seen locally during 2nd summer (Mar-Jul)
|5 (4.3%) *
|2 (1.7%) #
|Recorded at a distant location (>20 km)
$ it is too early to compare 2011 with previous years * 3 rings found from birds that failed to fledge # 2 rings found from birds that failed to fledge
After the success we've had with the Gulls we've started a similar but separate project colour ringing Common Terns. The rings are obviously much smaller than the gull rings - and dark blue with a three character code engraved in white, we're starting with codes E01 to E99. Common Terns legs are nowhere near as visible as Black-headed Gulls so there's no way we'll get as many records - but they do go to even more exciting places and it'll be interesting to get an idea of how they move around.
After events at Moor Green we were only able to ring at Lea Farm and even there numbers were a bit disappointing but we did manage to colour ring 10 of the 12 birds, the last 2 birds were too small for the colour rings and were only ringed with metal rings.
First year Common Terns don't often return to the UK so whilst we may get some sightings before they leave the country we'll probably have to wait until 2013 before we see these birds again. Hopefully some will be seen on their migrations - ringing recoveries of British bred birds in West Africa aren't uncommon and some adult ringed birds have reached South Africa and one even turned up in Australia!