Gannets must love Bempton Cliffs. Back in the 1970s there were only about 20 pairs breeding, but by 2012 there were 11,000 pairs and 1000 non-breeding birds (see graph). A look around the reserve suggests that the number has continued to rise.
One of the results of this increase has been that Gannets are nesting in new areas – last week I took a 1984 photo of the Nettletrip Guillemot productivity monitoring plot up to the cliffs and counted 23 new Gannet nests on the plot since it was taken, including four new nests since I monitored the plot last year. From watching the behaviour of some of the young non-breeding Gannets on the plot this summer, I think that there will be at least two or three more nests next year. Remarkably, this expansion doesn’t appear to have affected Guillemot productivity on the plot since the start of productivity monitoring in 2009 - but we will continue to keep an eye on this.
Visitors to Bempton can see one of our ‘pioneer’ Gannets from the Bartlett Nab viewpoint – sitting in solitary splendour now that most of the neighbouring Guillemots have left the cliffs.
The Bartlett North Guillemot diet plot - what's that Gannet doing here? It didn't nest there last year!
Another result of the population increase has been more young Gannets loitering around the cliff tops - where they appear to be landforming the boulder clay that sits on top of our chalk cliffs into terraces suitable for nest sites. Check out these photos:-
Young Gannets on the cliff top - look closely and you can see the amount of brown in the plumage of many of these birds indicating that they are younger birds. See also the contract between the amount of vegetation removed and the area which the Gannets aren't using.
The aftermath of Gannet vegetation removal - the areas they use are easy to spot.
Will the removal of the vegetation increase the amount of erosion on the cliff top? Will these birds try to nest in this area next year? If they do, they will be vulnerable to land predators. We are already considering the feasibility of electric predator fencing on the cliff top – if it does go ahead I hope that I don’t have to install it! Watch this space. There’s never a dull moment at the Bempton Cliffs seabird city.
Mike Babcock – Seabird Research Assistant