Last week I accompanied scientists from Exeter and Plymouth Universities to our RSPB reserve of Grassholm, home to nearly 40,000 pairs of northern gannets, making it the 4th largest colony in the world for this species and accounting for nearly 10% of the entire world population.
This was the 3rd of three trips this year, the purpose being to deploy small GPS devices on around 40 gannets to track their feeding trips to and from the colony. Grassholm is of international importance for this species and while we can protect them at their breeding site, legislation to protect them at sea is still sorely lacking (despite the Marine and Coastal Act being passed in 2009....). As well as answering scientific questions this work will contribute vital data to the cause of establishing Marine Protected Areas.
Led by Dr Steve Votier from University of Exeter this work is now in its 8th year meaning that an impressive pool of data has built up over the years.
Gannets can weight up to 3kg and the GPS devices are tiny in comparison accounting for less than 2% of overall body weight. Devices are deployed on day 1 of each trip and retrieved on day 3. Any that are missed are picked up on the following trip a week later. Should any be outstanding at the end of the third trip the devices will fall off after around 2-3 weeks as the adhesive tape wears out meaning there is no risk of birds being left with devices permanently attached.
To see a recent paper by Steve's team click here
Some photos of the trip plus some GPS tracks are shown below
Sam Cox and Steve Votier attaching a GPS device to a gannet
GPS device attahced to gannet
43 tracks from 2012 showing foraging trips to and from the colony. Each colour represents an individual bird. The star symbol shows the location of Grassholm
Rocio Moreno attempts to act as 'scribe' while contending with some of the million of greenbottles that swarm over Grassholm and make working tough at times!
Most chicks, like this one, are around 3 weeks old at this stage - some up to 4 or 5 weeks