Bass Rock Gannet Count

New technologies help researchers to quantify the impact of Avian Flu on the World’s largest Northern gannet colony.

Researchers have found that the Bass Rock gannet colony, the largest Northern gannet colony on the Earth, has reduced by 25-30% since the last major count in 2014. The latest findings were a result of a partnership between the Scottish Seabird Centre, The University of Edinburgh’s School of Geosciences, and the UK Centre for Ecology & Hydrology. The group collected imagery from a state-of-the-art drone, implemented automated counts and combined this data with traditional seabird counting methods to help them understand the impact Avian Flu had on the island’s gannet population.

Highly Pathogenic Avian Influenza (Avian Flu) has been spreading through seabird colonies around Scotland since 2021, causing widespread mortalities. The disease was confirmed on the Bass Rock in June 2022, at the height of the gannet breeding season. Following this discovery thousands of seabirds died on the island, resulting in an extremely disrupted breeding season. A colony count undertaken in June this year indicates that the size of the gannet population has decreased from 75,000 sites to around 55,000 sites.  A ‘site’ in the colony is an area occupied by a single bird or pair. Despite this significant and concerning decline, the 2023 breeding season has shown some hopeful signs of recovery, with no evidence of widespread mortality this summer.

Advances in the technology now available to monitor breeding gannets and interpret survey results have brought with it opportunities to better understand the colony in the wake of the disease. The research on Bass Rock this year has included drone surveys and machine learning trials, led by the University of Edinburgh’s Airborne Research and Innovation Facility. 

“We have been delighted with the performance of the drone in the gannet colony. The data quality surpassed our expectations and we were able to operate the drone without any disturbance to the colony. The implementation of the machine learning methods allowed a fast assessment of the colony, and identified live, dead, nesting and flying gannets. Going forward we plan to publish these early findings, with our partners at the Scottish Seabird Centre and UKCEH, and continue to develop and refine the machine learning methods in wild bird colonies.”

Dr Amy Tyndall & Tom Wade, School of Geosciences & Airborne Research and Innovation Facility, University of Edinburgh

“Until the outbreak of Avian Flu in 2022 the Bass Rock colony had increased relentlessly for more than a hundred years becoming the world’s largest gannet colony in 2014. Over this period counting methods have improved dramatically but the development of new technologies couldn’t have come at a better time and will give us the best chance of documenting how the gannets respond to the unprecedented impacts of Avian Flu.” Professor Mike Harris and Professor Sarah Wanless, Fellows at the UK Centre for Ecology & Hydrology.

“We were devastated to see the impacts of Avian Flu on the Bass Rock colony during the 2022 breeding season. While it has been reassuring to see signs that the colony is starting to recover, Avian Flu remains a significant concern.

Many of our internationally important seabirds are already affected by a range of pressures, including the impacts of climate change, invasive species, exploitation of the marine environment and pollution. It is more important than ever for Scottish Government to accelerate the production of a Scottish Seabird Conservation Strategy and prioritise actions that will restore and protect marine habitats. Without urgent action, some of our most iconic seabirds could be extinct within 30 years.”

Emily Burton, Conservation Officer at the Scottish Seabird Centre.

© School of Geosciences & Airborne Research and Innovation Facility, University of Edinburgh

©Emily Burton

Image credits: 

Bass Rock gannet colony drone image June 2022 © School of Geosciences & Airborne Research and Innovation Facility, University of Edinburgh

Gannet showing black eye indicating exposure to Avian Flu April 2023 © Emily Burton, Scottish Seabird Centre

Bass Rock gannet colony - June 2014 ©Stuart Murray, June 2022 and June 2023 © School of Geosciences & Airborne Research and Innovation Facility, University of Edinburgh


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Key Facts about Scotland’s marine environment