It's all go up on the cliffs for both the birds and the seabird monitoring team. Mike, one of our dedicated volunteers, has decided to give us some background to their work in his latest update.

Now that the monitoring season is in full swing I thought I’d try to explain how the seabird monitoring programme at Bempton Cliffs works. The scientific work done behind the scenes is a key part of what happens at Bempton.

Essentially there are two kinds of monitoring going on – productivity monitoring and population monitoring. Both are carried out in accordance with techniques included in the Seabird Monitoring Handbook for Britain and Ireland published by the JNCC. By using standard techniques we ensure that our results are comparable year to year and with other colonies monitored using the same methods.

Herring gull, photo by Andrew Harrison 

Photo: Andrew Harrison

Selection of nests

Productivity monitoring measures breeding success. For each species we check a selection of nests – usually 50 - on plots scattered throughout the colony at Bempton and Flamborough. Ideally, plots would be selected randomly, but at Bempton we are constrained by which areas of the cliff we can see and monitor safely and so we use the same plots year to year. At each visit the status of the nest (egg presence (and clutch size if relevant), chick presence/numbers, etc) are recorded until the nest fails of the chick or chicks fledge.

Our guillemots and razorbills are checked every three days, gannets, fulmar, herring gulls and kittiwakes are checked weekly. At the end of the season we can check productivity by plot and across the colony by dividing the number of fledges chicks by the number of nests monitored.

Massive task

Population monitoring measures trends in colony numbers. At its simplest a series of counts of all birds in a colony is made and an average taken – the reason for multiple counts is to reflect that a single count will miss some birds. At Bempton this would be a massive task - the colony stretches from Flamborough nearly to Filey.

Guillemot by Neil Gregory

 Photo: Neil Gregory

So we count the same sample plots every year to give us a snapshot of changes in the overall population. The exact method used varies by species. Guillemots and Razorbills are counted individually. Kittiwakes are counted by ‘Apparently Occupied Nest’. Using these standard techniques means that we can compare our data with other colonies to try to build up a larger picture of what’s happening with UK seabirds.

It’s a huge task. The two residential volunteers are on the cliffs for 8+ hours two days out of every three. An army of other volunteers – including RSPB staff who like nothing better than to spend their spare time counting guillemots or trying to get a look into 50 Gannet nests – are out carefully checking their plot or plots every day of the week. And the data we gather is one small piece of the jigsaw that is understanding what is happening to seabirds in the North Sea and beyond.