Gannet population decreased by nearly 30% after bird flu outbreak

The Bass Rock gannet colony has declined by nearly thirty percent after a severe bird flu outbreak, raising concerns among conservationists. Despite slight stabilization in recent surveys, breeding success remains low, highlighting ongoing challenges for the seabird population.

The world's largest northern gannet colony has undergone a substantial decline, with numbers falling by almost one-third following a severe outbreak of bird flu. This reduction has raised significant concern among researchers and conservationists monitoring seabird populations in the region.

Bass Rock Colony Details

Bass Rock, situated near North Berwick in the Firth of Forth, hosts more than 100,000 seabirds. Despite its size, breeding success within the colony remains low, highlighting persistent challenges for the species. Drone surveys carried out in 2024 and 2025 have offered detailed data on population trends and recovery attempts.

Population Trends and Survey Outcomes

Drone surveys conducted in 2025 showed that the colony's population had stabilized after the highly pathogenic avian influenza (HPAI) outbreak, which had severely impacted the 2022 breeding season. Overall, the colony is estimated to have decreased by roughly 30% since the outbreak.

Aerial photography in July 2025 identified 52,459 Apparently Occupied Sites (AOS), representing nesting locations used by individual birds or pairs. This number reflects an increase of about 6,000 AOS compared to 2024, yet remains approximately 22,800 below the last full pre-HPAI count carried out in 2014.

Research and Monitoring

The population study was conducted by a collaborative team from the Scottish Seabird Centre, Edinburgh Napier University, the University of Edinburgh's School of Geosciences, and the UK Centre for Ecology and Hydrology. Researchers observed population declines across most survey areas and found no evidence of significant recovery.

Emily Burton, conservation manager at the Scottish Seabird Centre, highlighted the impact of avian influenza on seabird populations, especially at Bass Rock. She stated that the gannet population had fallen by almost a third and emphasized the importance of minimizing pressures on these birds to support their recovery.

Mortality and Wider Effects

Nature Scot estimated that at least 11,175 gannets died during the 2022 outbreak. Other seabird species, including great skua, guillemot, and kittiwake, were also heavily affected. Globally, it is estimated that the HPAI outbreak caused the deaths of approximately 97 million birds.

Breeding Success and Technology Monitoring

Researchers used remote ground-based cameras to track chick-rearing success within the colony. The loss of experienced adult birds, coupled with ongoing challenges at sea, has negatively impacted breeding outcomes. Dr. Sue Lewis from Edinburgh Napier University explained that combining drone surveys with remote camera monitoring has provided unprecedented insight into breeding performance and population size.

Dr. Lewis noted that these technologies have improved the accuracy and efficiency of population counts and offered detailed views of breeding behavior. Following the 2022 outbreak, drones and cameras have been essential in assessing how the colony is recovering.

Conservation Importance

Bass Rock continues to be a crucial site for one of the world's largest seabird colonies. Conservationists stress the need for ongoing monitoring and protection measures to support the long-term survival of gannets and other affected seabird species.

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Author: Lucas Grant
Lucas Grant is a sports journalist with extensive experience covering football and basketball championships. Known for factual accuracy and an engaging, dynamic writing style.