As well as living and working on Ramsey, Lisa and I are also privileged to look after Grassholm, a tiny 9 ha rock lying 7 miles West of the Pembrokeshire mainland and home to 40,000 pairs of Northern Gannet. It is the RSPB's oldest reserve in Wales being purchased in 1948; at the time it played host to a mere 7,000 pairs. Today it is the 4th largest colony in the world for the species with around 10% of the world population.
There are no public landings on the island due to the disturbance this would cause. RSPB staff land on a handful of dates during the season to carry out monitoring and research work, the latter with Exeter University. A few days ago Lisa and I landed for the first time this season and spent a few hours carrying out productivity work. This involved mapping several study plots and recording how many incubating birds they contained. When we return in August we will check how many of these nests contain large chicks likely to fledge.
Most birds were still on eggs but quite a few had small 1 week old chicks and a couple had chicks that were around the 2 week mark and had developed the characteristic white down. When sitting quietly looking through the telescope it was interesting to see these large often quarrelsome birds gently tending to their single white egg. They incubate them under the feet, using their large webs (see photos below).
Correctly incubated egg - the bird is moving it into position to brood it under its large webbed feet
One bird on the edge of the colony which was probably an inexperienced breeder clearly hadn't got the hang of this and the egg could be clearly seen poking out of the side of the bird receiving little in the way of incubation and in full view of marauding gulls! (see photo below) The bird was oblivious to its error and even shifted around several times as if adjusting the egg that it must have thought was between its feet where it should have been!
Inexperienced bird with incorrectly positioned egg visible to the side of the bird
Some readers will know that in the autumn we go out to cut free birds (chicks mainly) that are entangled in marine litter, mainly fishing line and rope. A study we did with Plymouth University a few years ago crudely estimated there might be up to 18 tonnes of plastic contained within the gannet nests on Grassholm. It is during these summer trips that you get a flavour for how these entanglements occur and the sheer volume of plastic at such a small site hits home how much must be floating around undetected in our oceans
Gannets build their large domed nests out of seaweed and mistake plastic floating on the surface of the sea for it. They weave it into their nests and it creates a potentially deadly trap that wraps itself around the legs of chicks as they grow. Adult birds are not immune as they can become ensnared as they incubate. We watched a few padding around adjusting the egg (as in the photos above) all the while twisting plastic around their legs as they did so. Luckily the few we saw managed to free themselves but others will not be so lucky.
The white plastic packaging tape in the photo above is a particular problem. The edges are razor sharp and cut deep into the birds legs or wings often resulting in irreplable damage.
The sad sight of two adult birds that have succumbed - one ensnared by the leg, the other around the neck. Both would have slowly starved to death.
Despite the problem of plastic pollution in the marine environment the colony has continued to grow with each subsequent survey. There are greater threats to the future of Grassholm than plastic - climate change arguably one of the biggest. However it is important to highlight this issue as it causes a great deal of unnecessary suffering to many individuals and brings home starkly what a festering rubbish tip our oceans have become.
To end on a positive note! There were lots of non-breeding birds present last week. Studies by the Exeter team have shown that many of these will have come from other colonies around the UK as they stop off to investigate new colonies and help spread the gene pool. Grouping around the edge of the breeding birds they play out a scene resembling constantly bickering siblings, their disruptive antics causing unease to the nearby inexperienced birds breeding on the edge of the colony. But it is these birds that are the future of our gannet colonies and it was encouraging to see so many gathered on Grassholm last week. Many of the birds we saw will move on to breed elsewhere but many more will hopefully continue to settle on Grassholm and see this spectacular colony go from strength to strength.
A 2nd / 3rd year bird (I've really hedged my bets there but to be fair there is quite a lot of plumage overlap!) circling the colony last week. They achieve full adult plumage at 4 years old (sometimes 5!) and generally start to breed at 5 years of age
Many thanks to our local boat operator Thousand Islands Expeditions for delivering us safely to and from Grassholm last week and for sponsoring our seabird monitoring work. For details of their offshore boat trips that take you around Grassholm contact them on 01437 721721
Fascinating to read about the Gannets, but awful to see so much marine litter!