We are on track to achieve something remarkable in Aberdeen City: what could be the world’s first eradication of an invasive mammal from a mainland urban environment. Our ‘Grey squirrel urban eradication strategy for Aberdeen’ combines science, community action and innovative detection methods to protect the city’s native red squirrels.
Here’s an overview of our project and how it works:
Why We’re Doing This
The goal of our programme is simple: remove all invasive non-native grey squirrels from Aberdeen City. In doing so, we aim to support the recovery of native red squirrels in the city and across Aberdeenshire. To ensure the programme is effective, we also need to prevent future invasions by detecting and removing grey squirrels re-entering the area, as quickly as possible. Red and grey squirrels cannot live alongside each other. If nothing is done to remove the grey squirrels, we could lose our red squirrels entirely.
The population of grey squirrels in Aberdeen is a genetically isolated, island population. Read our blog about how grey squirrels first arrived in Aberdeen, and why this part of the country is in a unique position. This area is a gateway to the UK’s largest are of red-only squirrels – The Highlands and Grampians. We must protect this area, and prevent any grey squirrels from establishing here. We can do this by removing the threat from greys in the North East.
How the Programme Works
Our work is divided into three key phases:
- Eradication Phase: Detecting, trapping, and removing grey squirrels as efficiently as possible.
- Confirmation Phase: Monitoring to ensure eradication has truly been achieved.
- Biosecurity Phase: Long-term measures to prevent reinvasion and protect red squirrels.
Principles of Eradication
Eradication is guided by three main principles:
- Target the entire population, not just individual squirrels.
- Prevent new individuals from entering the population.
- Remove individuals faster than they can reproduce.
By following these principles, we have a real chance for complete eradication in Aberdeen City!
This happy red squirrel just heard about our work! (c) Harry Morgan
Challenges and Innovations
As we reduce the grey squirrel population, detecting the last remaining individuals becomes increasingly difficult. Sightings are often brief or lack evidence, which can take significant time to verify.
To improve detection, we have introduced our fantastic scent detection dogs, Tarka and Sika, and their handler, Libby. The scent detection team adds a new layer of monitoring alongside public sightings recorded on our squirrel sightings map , and hair samples collected at feeder boxes across the city. This combined approach greatly increases our chances of locating the remaining grey squirrels. You can read more about the scent detection dog team here!
Management Zones
We have divided Aberdeen City into 17 Management Zones (MZs). Breaking the city into zones allows us to tackle eradication zone by zone, focusing resources where they’re needed most, rather than trying to manage the entire city at once.
How close are we?
Withing the Confirmation Phase of the project, we are strategically surveying each Management Zone, including with our scent detection team, and then placing each zone in one of these categories:
- Active: Grey squirrels have been recorded within the last eight weeks
- Inactive: No grey squirrels have been recorded within the last 8 weeks
If a zone has been inactive for two years, this suggests all grey squirrels have been removed, and the zone moves to the Biosecurity Phase of the project, where our focus in ensuring no new greys can enter the zone.
Here’s where we are currently:
- Five Management Zones are in the Confirmation Phase. One is active, where grey squirrels are still present and removal efforts are ongoing, and the remaining four are inactive, three have had no grey squirrel records since June 2024, one had a confirmed grey squirrel in June 2025.
- The remaining Management Zones are already in the Biosecurity Phase, meaning no grey squirrels have been recorded in the last two years.
Overall, this means most of the city has reached the final stage of the Eradication Project, with only a small number of zones still requiring confirmation or active management. This demonstrates a strong progress towards complete eradication.
Biosecurity Phase
After eradication, the Biosecurity Phase will protect the city from any incursions and keep it grey-free. This means looking beyond the city’s boundaries to monitor and control the nearest grey squirrel populations in other SSRS priority areas.
Core Protection Zone: Aberdeen City, where red squirrels are established.
Containment Zone: A defensive buffer between Aberdeen City and grey squirrel populations to the South.
Prevention Zone: Areas with established grey squirrels, where the goal is to prevent further spread.
Over the next four years we will focus on knowledge transfer and upskilling stakeholders in Aberdeen, empowering them to champion biosecurity in the city.
Achieving a World-First
Once completed, our project could become the first example of urban grey squirrel eradication worldwide. It demonstrates that with the right combination of science, community involvement, and innovative methods, complete eradication is achievable – even in a city!
One of the main factors that has contributed to the success of the project so far is collaboration. We could not have achieved this without the incredible support of the SSRS partnership and funders, volunteers, and the Aberdeen City and Aberdeenshire community. In particular, Aberdeen City Council have been a huge asset to the project, helping us with accessing land, running engagement events and spreading the word about the good work we’ve been doing together. This is a fantastic demonstration of a local authority leading the way in invasive non-native species management.
Follow us on Facebook and BlueSky, and sign up to receive our newsletter to keep up to date with the eradication in Aberdeen, and the rest of SSRS’s work.