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England-Wide Grey Squirrel Suppression Gave the Highest Modelled Red Squirrel Recovery Potential

Eurasian red squirrel in woodland at Formby, England
Conservation · Management

Large-scale suppression of invasive grey squirrels offered the highest modelled potential for widespread recovery of Eurasian red squirrels (Sciurus vulgaris) in England, according to a recovery strategy published by Natural England on 14 April 2026. The project compared 18 alternative strategies over a 25-year period and weighed biological outcomes against cost, animal welfare, public acceptability and other impacts.

The strategy was developed through a structured decision-making process led by the Zoological Society of London for Natural England, with input from more than 60 stakeholders. The alternatives combined different levels of grey squirrel (Sciurus carolinensis) management with red squirrel translocations and possible future tools, including grey squirrel fertility control and a squirrelpox vaccine. Squirrelpox is carried by grey squirrels with little apparent effect on them, but can be fatal to red squirrels and is one of the main mechanisms by which grey squirrels contribute to red squirrel decline.

Doing nothing did not deliver recovery

The biological model projected squirrel population dynamics and disease spread over 25 years. Under the model, doing nothing, continuing the current status quo, or replacing lethal grey squirrel management with fertility control alone if that tool becomes available all failed to deliver red squirrel recovery and carried a high probability of extinction across mainland England.

England-wide suppression of grey squirrels gave the strongest prospects for large-scale red squirrel recovery. However, the report also found that this option came with high monetary costs, high potential for non-target bycatch, animal-welfare concerns and low predicted public support.

Regional strategies also showed promise

More targeted regional strategies in northern and south-west England also produced promising modelled outcomes, particularly when local grey squirrel management was combined with red squirrel translocations. Natural England’s summary notes that these approaches could achieve comparable long-term persistence outcomes at lower cost, with stakeholders expressing a preference for the northern England options. The full report also found a trade-off: translocations increased modelled squirrelpox mortality because they created more overlap between red and grey squirrel populations.

The project did not select a final national programme for implementation. Instead, the report provides an evidence-based framework for a subsequent decision on which strategy should be taken forward and can also be reapplied at smaller spatial scales.

Sources and image credit

  1. Natural England. (2026). England Red Squirrel Recovery Strategy (Natural England Commissioned Report NECR669). https://publications.naturalengland.org.uk/publication/6061891536027648Primary commissioned-report record published 14 April 2026. The project evaluated 18 strategies using a 25-year biological model plus cost, welfare, bycatch, public-acceptability and socio-economic objectives.
  2. Walsh, K. (2026, April 14). England Red Squirrel Recovery Strategy. Natural England. https://naturalengland.blog.gov.uk/2026/04/14/england-red-squirrel-recovery-strategy/Official Natural England summary of the report’s main findings and trade-offs.

Image: Peter from Liverpool — Eurasian red squirrel at Formby, Merseyside, England, photographed 26 August 2006; Wikimedia Commons / Flickr; representative English red squirrel image, not an animal from the Natural England modelling project · CC BY-SA 2.0 · Source

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