Monitoring the UK’s largest mainland breeding seabird colony
Seabird population data has been collected around Flamborough, Bempton and Filey for many years. This vital data helped to determine the importance of the area to seabirds and was integral to the Special Protection Area (SPA) extension in 2018, which formally created the Flamborough and Filey Coast SPA.
In 2009, a comprehensive seabird monitoring programme was established as a collaboration between the RSPB and Natural England. The purpose of the programme is to monitor annual changes in the breeding success of individual species, as well as carry out a full colony count every five years. The data is shared with partners to inform management of the SPA and is added to the national Seabird Monitoring Programme dataset, managed by the British Trust for Ornithology.
National Seabird Monitoring Programme2025 Summary Results
Click on each seabird below to read a short summary of the data collected this year. Scroll to the end of the page to read the RSPB’s full report.
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After a few years of improving trends, Kittiwakes had a poor year with a mean productivity of 0.50 chicks per pair. Across the colony, 860 Apparently Occupied Nests were monitored, with 435 chicks fledging.
Alongside chick mortality, there were high numbers of young chicks being left unattended in nests, which may point to a problem with prey availability.
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Gannet productivity remained at 0.74 fledged chicks per Apparently Occupied Nests. In total 246 chicks fledged across a total of 332 nests. This is the same productivity as 2024 and is an encouraging sign of continued recovery after the impacts of avian flu in 2022.
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From the 115 Apparently Occupied Sites monitored over the breeding season, a mean productivity of 0.48 chicks fledged per pair. This is the highest productivity since 2021 but the general trend remains one of slight decline.
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Across 58Apparently Occupied Sites, 40 chicks successfully fledged resulting in a mean productivity of 0.71 chicks per pair. This is a decrease of the productivity of 2024, but remains higher than other historic records.
The number of nests monitored declined from 82 in 2024 to 58 in 2025, demonstrating the general decline in the cliff-nesting Herring Gull population.
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This year, one shag nest was monitored which successfully fledged two chicks.
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A small plot at Filey North held 4 Apparently Occupied Nests, with eight chicks fledging resulting in a productivity of 2.0 chicks per pair.
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A total of 243 Apparently Occupied Sites fledged 128 chicks, resulting in a mean productivity of 0.53 chicks per pair.
This productivity is the lowest on record, however, due to the closure of Grandstand viewpoint, only a single plot was monitored at Bempton Cliffs reserve.
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Across 244 Apparently Occupied Sites, 88 chicks successfully fledged, resulting in a mean productivity of 0.32 chicks fledged per pair.
This is a large decrease in productivity from the 2024 results. Predation was seen to impact some monitoring plots, and the closure of Grandstand viewpoint meant only limited data captured from Bempton Cliffs.
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A pre-breeding survey of Puffins ‘staging’ on the sea was carried out this year, with approximately 3080 individuals counted.
It is important to stress that this survey is not designed to provide an accurate census of the breeding population. A productivity figure is not possible due to the nesting behaviour of puffins.
How is breeding success data collected?
Each spring, a dedicated group of RSPB staff and volunteers carry out productivity monitoring for Gannets, Kittiwakes, Herring Gulls, Fulmar, Shag, Cormorant, Guillemots and Razorbills. This data helps to determine breeding success of each species and gives us an idea of what is happening within the colony every summer. Breeding success can be impacted by local challenges such as predation and bad weather, alongside wider pressures on the colony including climate change, food availability and human activities at sea. Monitoring these changes over time provides a unique view into the lives of our seabirds.
Each seabird monitoring volunteer is assigned a ‘plot’ (an area of cliff with good visibility of breeding seabirds and provides a safe vantage point) and chooses 50 nests within that plot to monitor over the course of the breeding season. The contents and outcome of every nest are recorded, but the frequency that plots are monitored varies between species based on how quickly chicks develop. For example, Kittiwake nests are checked and progress is recorded once a week whereas Guillemots are visited every three days.
The iconic Puffin makes use of the holes, cracks and crevices in the sheer cliffs to raise their single chick. This is perfect for protecting against predators and the biting North Sea wind, but it’s not great for monitoring productivity. Instead, RSPB staff monitor how many Puffins arrive at the start of the year to get an idea of the population’s health. Before Puffins find their nest and begin to breed, large numbers will gather on the sea around the cliffs for a short time. With quick reactions from RSPB staff, the number of adults counted can be used to monitor any year-on-year largescale changes in population.
National Seabird Monitoring ProgrammeHow are the full colony counts carried out?
Counting every adult bird within the UK’s largest mainland colony is a huge undertaking which requires a lot of skill and good weather! The full colony counts take place roughly every five years and are completed by a core group of experienced RSPB volunteers and staff. The geology of the cliffs around Flamborough and Filey means that much of the count has to be done by boat, with land-based counts ensuring that the entire site is covered.
The periodic full colony counts give us an idea of how each species is faring across the population. This gives us a ‘bigger picture’ view on both the Flamborough and Filey Coast SPA and the wider marine ecosystem. As long-lived and mobile species that rely on many other aspects of the marine environment, seabird population changes are often reflective of wider problems. Any fluctuations in seabird numbers can provide a piece of the puzzle to understanding the local and national impacts of international issues, such as climate change.
Coupled with annual productivity monitoring, this robust dataset allows RSPB and Natural England experts to assess how healthy the colony is and whether there are any significant population trends emerging over time. As part of the national Seabird Monitoring Programme, this information is vital to understanding similar trends across all of the UK’s seabird colonies.
Seabird Monitoring Reports
With thanks to the team at RSPB Bempton Cliffs for supporting the development of this page
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