As well as looking after Ramsey Island, we also have responsibility for Grassholm Island, two of Pembrokeshire's finest islands, (not that I'm biased!)
Grassholm lies 7 miles south west of Ramsey off the Pembrokeshire coast and is home to the only colony of northern gannets in Wales. We carry out an aerial photographic survey every five years to establish the number of breeding pairs on the tiny island (a mere 9ha in size).
In 2004 the figure stood at 32,094 pairs. Following the 2009 survey this has increased to 39,292 pairs, an increase of 22%. This confirms Grassholm as the 3rd largest colony for this species of gannet in the world (behind St Kilda and Bass Rock (both in Scotland)) and accounts for 9.5% of the entire world population of this species! As a result Grassholm is designated as a National Nature Reserve and a Special Protection Area.
The question most commonly asked is "how to you count 39,292 pairs?!" The answer is, luckily, I don't! We employed an environmental consultant, Stuart Murray, an expert in this field, to carry out the task. He has counted the colony for the past 2 surveys (spanning 10 years) so this helped to keep the counting consistent. Firstly he had to hire a light aircraft, fly over the island (at a height of no less than 1000ft to avoid disturbing the birds) and then take hundreds of photographs on his state of the art digital camera. He then picked 8 of the best photos that gave 100% coverage of the island, enlarged them to A3 size and spent many...many..hours counting each individual bird on a nest!
So why the increase? Firstly, some of it is real. There are areas that have obviously increased when you compare previous photos. Over the past 10 years gannets have bred very successfully. Between 70 and 80% of nests have fledged a chick. A sufficient number of these have returned to breed and accounted for some of the increase. However, some of the increase, and it is impossible to say how much, is down to improved camera technology. In 4 years things have come a long way, the quality of image is now far superior and you can zoom in much further. What we can safely say is that this is the most accurate count of the colony that we have ever had.
The next survey is due in 6 years time. How much further can the colony increase?!
There are no public landings permitted on Grassholm due to the disturbance this would cause the breeding birds. However you can take a boat trip around the island to experience this amazing spectacle. Contact the RSPB contracted boat company, Thousand Island Expeditions, on 01437 721721 for more details. Due to the distance the island lies offshore, good weather conditions are required to get out there. As we head into autumn these become few and far between. Trips may run to the end of September if we get a calm spell, otherwise try again in spring or summer 2010.