Monitoring

Background

Regular checks on seabird nests during the breeding season enables us to assess their 'productivity', the number of fledglings produced per breeding attempt, gain information on 'phenology', the timing of breeding and estimate population sizes. Around the world, long term studies of these factors have told us about how seabirds respond to changes to environmental factors such as prey availability, weather and human impacts. Compared to most studies of this type, our time series is currently very short in duration!

Some species are easier to monitor than others and we are limited in terms of access to the island and the use of volunteers and students, so our work focusses on key indicator species such as shags and kittiwakes. We follow methodology set out by JNCC's Seabird Monitoring Programme, and submit each year's data to their database. Some of our data are presented here.

Productivity

Kittiwakes usually lay two eggs per year and shags usually lay three. Even with our short time series you can see that as in many other UK colonies productivity (breeding success) in both species can vary substantially between years. The very cold winters of 2012/13 and 2013/14 may have something to do with the low breeding success of kittiwakes in 2013 & 2014 and you can see that shag productivity was also low in those years. It has been pleasing to see something of a recovery since then.