Great Black-backed Gull project - Dublin

 

Great Black-backed Gulls are the largest Gull in the world.  Over the years I could see their numbers declining, but anecdotal opinion means nothing .  In 2017 we started Colour Ringing them in order to provide accurate Adult Survival date to international best standard practice.  There was a previous colour ringing Project in Dublin so we inherited 100 GB's already colour ringed.  We have Colour Ringed almost 800 since we started.  Mainly as Chicks but many caught and ringed as adults.  I do a RAS, it stands for Re-trapping Adults for Survival.  However with the colour rings I don't have to re trap so Re-sighting Adults for survival.

The data required for the project is simple.  We need to identify every colour ringed individual Great Black-backed Gull in the Project boundaries from Mid March to  Mid August.   How accurate our data is the more accurate the survival data is.  So each year it is a huge effort by a small group of us reading GB's rings at every opportunity.  Covid restrictions, bird Flu precautions have hit the project hard but each year we bounce back

Of the 800 Gulls ringed,  I don't expect that many to be in the project each year.  Maybe only 200 - 300 are possibly still alive, a good year would to record over 100.

1. They don't breed until generally 5 years old, so chick ringed between 2020 - 2024 may not return to Dublin.  
2. About 50% don’t nest on the Island they hatched on.  Luckily some nest on the other Islands in the project, but others go to the Calf of Man, Saltees, and various other colonies.  
3. About 32% of chick survive the 5 years to breeding age.  These are scattered currently far and wide but with good ring readers in NI, we know many favour that direction.  But as far as Cork, Waterford, Wexford we get regular sightings of Juveniles (and adults who couldn’t be bothered returning to breed even though they are 5 years old).

 

Difficult to display as a graphic as to were the project is at this stage of the season.  Each column represents about 85 Colour rings deployed.  We are now just over 50 identified, but many Islands have not yet been visited due to Ferry, Tides, Sea Conditions etc.