Barnacle goose rings - why bother?!

 A (very!) few people have asked us about the rings on legs of barnacle geese and why some people spend so much time looking at them, so here’s an attempt at a summary of why, what and how.

Geese are caught by setting cannon nets near pre-baited locations. A plastic coded ring is placed around the leg and the bird is weighed, measured and released, entirely unharmed. Most ringing of the Greenland barnacle goose population takes place in their wintering grounds of western Scotland and Ireland. Although barnacle geese are flightless for a period after breeding, the remote locations they inhabit in Greenland prevents much summer ringing. The rapidly growing Iceland population is different. They are more accessible and can be corralled and ringed at their breeding sites, a far easier process, and probably a higher percentage of the Iceland population is ringed as a result.  

Recording re-sightings of these birds gives detail on age, migration route and dates, wintering locations and some insight into behaviour - it’s great to be able to identify family groups or pairs, sometimes seeing the same birds habitually feeding in the same field year after year – and birds that have come from or will go to other parts of Scotland and Ireland. It really serves to underline the importance of Islay as a hub for much of the Greenland barnacle goose population and how mobile these wintering populations are, depending on weather, grazing availability and who knows what other factors.

The majority of the ringed barnacle geese on Islay were caught and ringed under licence by Steve Percival, who has been ringing on Islay for many years now. Steve gave us some more information…

“With regard to interesting histories, these range from birds coming back to the same few fields on the reserve year after year after year (LBL was probably the best example of this, seen every year for 25 years since it was ringed, with virtually every sighting on the RSPB Loch Gruinart reserve), through to more mobile individuals (such as the family that are currently hanging out in northern Spain). Other more distant recoveries included VUP, a well-twitched bird that went to New York (first seen in a car park in the Bronx), one shot in Ontario, and a pair that headed down to Cornwall for a brief trip before returning to Islay.”

…plus a few helpful pictures to illustrate 

 Most of the two letter darvics have a line between the characters, running continuously around the ring. The ring in this instance is Blue C A. There are currently blue, yellow, orange and white coloured rings in use. Blue, yellow and orange rings mean the bird was ringed in Iceland. The white rings are most common and are also used in Iceland but most will be from ringing schemes in Scotland and Ireland. 

 

 The vast majority of ringed birds will have a metal ring on the opposite leg. These rings can only be read if the bird is re-caught or found dead. Many of them will also have a coloured band or bands, though these are more fragile and tend to drop off with age. Recording this extra information can help to confirm ring identity. These birds would be identified as white YVS plus green and white YYB plus green.  

 The characters are printed multiple times around the ring. What could look like FRI on first sight is really EBL, currently the oldest known barnacle goose on Islay.

Speaking about the benefits of the data gained from all this activity, Steve said “We’ve also been able to confirm the very low exchange of birds between the Greenland and the Svalbard populations. The main value of the ringing, though, is in providing data on the survival and movements rates of the population as a whole, in terms of how many make it from one year to the next and how this has varied through time (actually survival has been remarkably stable until the introduction of the recent Islay goose scheme where survival unsurprisingly has dropped substantially). We’re still working on determining the effects of the scheme on movement rates away from Islay. Early results from the ringing in relation to Iceland seems to be showing that most of the birds breeding there are from wintering sites away from Islay.”

The Islay goose scheme that Steve refers to is run by NatureScot, who are combining compensatory payments to farmers with an active cull of barnacle geese by licensed marksmen working on Islay through the winter. NatureScot are seeking to reduce the amount of birds wintering on Islay to around 27,000. Information gained through ring re-sightings is likely to prove important in understanding the intended and unintended consequences of the Islay scheme. 

So, for interest, here are some of the details of the codes used by the various barnacle goose ringing schemes that are most likely to be seen here on Islay

Iceland

2 characters on blue, white, yellow or orange rings. All have a line between the characters

Svalbard (not common here)

3 characters on an orange ring

Ireland

3 characters on a white ring, mostly with 2 letters then a number. Malin ends 3 or 6, Sligo ends 9 and Inishkea (Mayo) have 3 characters starting I or 9 also with multiple coloured spiral rings

Islay

3 characters on a white ring with 3 letters or starting with a number, EXCEPT 4-- (Orkney, Durness or Oronsay), 3-- (Durness) and S-- (Tiree/Durness)

And this is just barnacle geese, there are also Greenland white-front, pale-bellied brent and greylag geese ringing schemes.

Some of these ringing schemes can be found and contacted via the excellent website cr-birding.org, or alternatively ring sightings can be sent to us at islay.birds@gmail.com and they will be forwarded on.

If there’s any mistakes in the above, that’s our fault. Please email us and we will be happy to correct. This isn’t intended to be gospel, it’s intended to raise awareness and encourage involvement. Many thanks to Steve Percival for his information and help.