Advice on squirrel management

Guidance documents

New guidance note on controlling grey squirrels

Gill, R., Ferryman, M., Shuttleworth, C., Lurz, P. W. W., Mill, A., Robertson, P. & Dutton, C. (2019) Controlling grey squirrels in forests and woodlands in the UK. Forest Research & Forestry Commission. UK Forestry Standard Technical Note. It can be download from the Forest Research website.

From the website – Grey squirrels (Sciurus carolinensis) have spread rapidly since their introduction into Great Britain in the late19th century, and Ireland in the early 20th century. They have a significant impact on woodland biodiversity, and in particular the native red squirrel (Sciurus vulgaris). Grey squirrels have displaced red squirrels throughout most of England and Wales, central and southeast Scotland, and parts of Northern Ireland, through competition and disease. Grey squirrels also pose a threat to the sustainable management of woodlands through the damage they cause to trees by bark stripping. Such damage may lead to a loss of particularly vulnerable tree species (e.g. beech) within the canopy of woodlands and this may be accompanied by a decline in associated fungal and invertebrate fauna. It some areas it can act as a disincentive to the creation of new woodlands for timber because it reduces the value of the trees. In many areas of the UK, grey squirrels are unaffected by predation and therefore targeted control is often necessary to reduce their impact on woodlands and biodiversity. This Technical Note provides updated information on methods of grey squirrel control. It has been produced in response to changes in legislation as well as recent developments in control methods and trap designs.

Red and grey squirrels

  • Gurnell, J., Lurz, P., Shirley, M., Cartmel, S., Garson, P., Magris, L., et al. (2004) Monitoring red squirrels Sciurus vulgaris and grey squirrels Sciurus carolinensis in Britain. Mammal Review, 34, 51-74.

Note: Critical review of data collected on monitoring red and grey squirrels in Britain, illustrating some of the difficulties in obtaining estimates of presence and numbers.

  • Gurnell, J., Rushton, S. P., Lurz, P. W. W., Sainsbury, A. W., Nettleton, P., Shirley, M. D. F., et al. (2006) Squirrel poxvirus: Landscape scale strategies for managing disease threat. Biological Conservation, 131, 287-295.

Note: Provides details of management of corridors and buffer zones around red squirrel protected areas.

  • Gurnell, J., Lurz, P. W. W., McDonald, R., & Pepper, H. (2009) Practical techniques for surveying and monitoring squirrels. Forestry Commission, Edinburgh, 1-12 pp.

Note: Comprehensive account of squirrel survey and monitoring methods; does not include camera trapping. Available from: www.forestry.gov.uk/pdf/fcpn011.pdf/$file/fcpn011.pdf

  • Gurnell, J., McDonald, R., & Lurz, P. W. (2011) Making red squirrels more visible: the use of baited visual counts to monitor populations. Mammal Review, 41, 244-250.

Note: Information on visual counts, one of the most common survey and monitoring methods, with the application of bait to enhance detection.

  • Di Cerbo, A., & Biancardi, C. (2012) Monitoring small and arboreal mammals by camera traps: effectiveness and applications. Acta theriologica, 1-5.

Note: Describes the application of camera traps to survey and monitor squirrels, particularly their presence.

  • Forestry Commission Scotland (2012) Managing forests as red squirrel strongholds. FC Practice Note 102. 16 pp. Forestry Commission Scotland.

Note: Covers management objectives and options with respect to tree species choice and forest operations for managing red squirrel strongholds in Scotland – also relevant to elsewhere in the UK. scotland.forestry.gov.uk/images/corporate/pdf/FCSStrongholdsGuidance.pdf

  • White, A., Bell, S. S., Lurz, P. W. W., & Boots, M. (2014) Conservation management within strongholds in the face of disease-mediated invasions: red and grey squirrels as a case study. Journal of Applied Ecology, 51, 1631-1642.

Note: Highlights the impacts of disease carried by grey squirrels on red squirrels and the difficulties in preventing disease outbreaks, with particular relevance to red squirrel strongholds.

  • Goldstein, E. A., Lawton, C., Sheehy, E., & Butler, F. (2014) Locating species range frontiers: a cost and efficiency comparison of citizen science and hair-tube survey methods for use in tracking an invasive squirrel. Wildlife Research, 41, 64-75.

Note: Compares the efficiency of volunteer based sightings surveys and hair-tube surveys for detecting the presence of red and/or grey squirrels.

Red squirrels

  • Pepper, H., & Patterson, G. (1998) Red squirrel conservation. Practice Note 5. 8 pp. Forestry Commission, Edinburgh.

Note: Practical advice on conserving red squirrels. Available from: www.forestry.gov

  • UK Red Squirrel Group (2004) Advice Note: Supplementary Feeding. 4 pp.

Note: Important guidance on providing supplementary food for red squirrels. Available from jncc.defra.gov.uk/pdf/rs_supfeed_v5.pdf

  • Parrott, D., Quy, R., Van Driel, K., Lurz, P., Rushton, S., Gurnell, J., Aebischer, N. & Reynolds, J. (2009) Review of red squirrel conservation activity in Northern England. Natural England Commissioned Report NECR019. Natural England, Sheffield. 109 pp.

Note: Critical review of then conservation actions that provides a framework for more recent conservation advice. Available from: file:///C:/Users/John/Downloads/NECR019%20edition%201.pdf

  • Shuttleworth, C., Lurz, P., & Hayward, M. (2015) Red Squirrels: Ecology, Conservation & Management in Europe, 328 pp. European Squirrel Initiative, Stoneleigh Park, Warwickshire CV8 2LG UK.

Note: Comprehensive and up-to-date review of red squirrel biology and management by leading European experts. The Volume includes chapters on: ecology, red-grey squirrel interactions, genetics, disease, management, reintroductions, British strongholds, modelling, monitoring and community involvement. Available from : www.europeansquirrelinitiative.org/

  • Gurnell, J., & Lurz, P. (2012) Red Squirrel. In J. Birks, S. Bullion, W. Cresswell & M. D. Dean (eds) UK BAP Mammals; Interim Guidance for Survey Methodologies, Impact Assessment and Mitigation, 9-21. The Mammal Society, Southampton.

Note: Best practice and advice on survey, monitoring, impacts and mitigation. Available from www.nhbs.com/title/196556/uk-bap-mammals

  • Shuttleworth, C., Lurz, P. W., & Halliwell, E. (2015) Shared Experience of Red Squirrel Conservation Practice, 209 pp. European Squirrel Initiative, Stoneleigh Park, Warwickshire CV8 2LG UK.

Note: Up-to-date compilation of current red squirrel conservation initiatives across the UK involving partnerships between volunteers, professionals and conservation organisations, particularly demonstrating good practice. Available from : www.europeansquirrelinitiative.org/

Grey squirrels

  • Mayle, B. A., & Broome, A. C. (2013) Changes in the impact and control of an invasive alien: the grey squirrel (Sciurus carolinensis) in Great Britain, as determined from regional surveys. Pest Management Science, 69, 323-333.

Note: Reviews tree damage by grey squirrels in British woodland over the last 80 years, and considers the efforts to control grey squirrels and the economic impact of bark stripping.

  • Shuttleworth, C., Lurz, P., & Gurnell, J. (2016) The Grey Squirrel: Ecology & Management of an Invasive Species in Europe, 532 pp. European Squirrel Initiative, Stoneleigh Park, Warwickshire CV8 2LG UK.

Note: Comprehensive and up-to-date review of grey squirrel biology and management by leading European and North American experts. Chapters include aspects of ecology, urban grey squirrels, disease and red-grey squirrel interactions, the possible impact of pine martens on grey squirrel populations, economic damage, population control and management, modelling and the wider impacts of grey squirrels on ecosystems. Available from : www.europeansquirrelinitiative.org/

  • Mayle, B., Ferryman, M., & Pepper, H. (2007) Controlling grey squirrel damage to woodlands. Forestry Commission, 16 pp.

Note: Guidance on controlling grey squirrels. Written with respect to tree damage prevention, but advice on use of Warfarin poison is no longer applicable since its use for this purpose is now prohibited. Advice on trapping control also relevant to red squirrel conservation. Available from: www.forestry.gov.uk/pdf/fcpn004.pdf/%24FILE/fcpn004.pdf

  • Pepper, H. (1998) Nearest Neighbour Method for Quantifying Wildlife Damage to Trees in Woodland. Practice Note 1, 6 pp. Forestry Commission, Edinburgh.

Note: Guidance on quantifying grey squirrel damage to trees. Available from: www.forestry.gov.uk/pdf/fcpn1.pdf/$FILE/fcpn1.pdf

Useful web sites

Current programme of red squirrel conservation across nine stronghold areas in England, Wales and Northern Ireland involving volunteers, academics and practitioners, led by The Wildlife Trusts.

A partnership project to halt the decline of red squirrels in core areas of Scotland.