Monday, 2 July 2012

Colour-ringing young gulls

A mini-expedition with the Tay Ringing Group

Every year the Tay Ringing Group ring gull chicks at the mixed Herring/Lesser Black-backed/Great Black-backed colony on St Serf's Island in Loch Leven in Central Scotland. Long-term monitoring of the birds in this way is a valuable tool in understanding the movements and life histories of these birds, one of which, the Herring Gull, is now Red-listed in the UK although its status worldwide and throughout Europe remains secure.

Gull colonies are chaotic, noisy and odoriferous places at the best of times and disturbance of any kind really ups the activity levels. Because of this ringers limit our visits to relatively short time spells so that disturbance is kept to a minimum and chicks are not left on their own for very long. We have permission to ring birds at this colony from SNH as part of a long-term monitoring project.
One anti-predator strategy by the chicks is to stay concealed under grass tussocks and once  I knew where to look, picking them up was quite easy. Each chick was taken back to the ringing site which was always close by so the chicks could be released near where we found them. Once in the queue waiting to be ringed the chicks relaxed, especially if placed on the ground and were very easy to manage. Only occasionally would one get up and make a run for it! 

So quickly a production circle was set up with metal rings, then Darvics (the individually marked plastic colour rings) dished out to the ringers once the birds had been identified. Young gulls can be a bit difficult despite the manuals giving clear illustrations of how this is done. Some birds just don't read manuals and can't be positively identified. In these cases the birds are released unringed - the golden rule - if you can't identify it - don't ring it! Everything is meticulously logged so that we know which bird is which and a big thanks to Julie for doing all the scribing!
So why put the colour rings on? Ringing recoveries are few and far between and often involve the bird having come to a sticky end. With individually marked colour rings the birds can simply be observed through binoculars or scopes or, in the case of gulls, whilst they are trying to steal your fish-and-chips, and the number and colour of ring sent in through the BTO website (link below). Advances in digital photography have enabled lots of birds to be photographed with colour-rings easily read and then submitted as recoveries. Each ring is unique and immediately identifies the bird.

So once they have both rings on they are ready to go. Maybe someone will see T:00C somewhere during the rest of its life and let us know what it's up to and where it is.
It was a great privilege to have been part of the team and I had a magnificent day. Hopefully to return and do a few more again next year.

Some links

Report a ringed bird through the BTO website - there is a purple button on the right

BTO Bird Facts - the Herring Gull

Tay Ringing Group