Red squirrel introduction to the Isle of Man

Credit: Melissa Nolan

Position Statement on the proposed introduction of red squirrels to the Isle of Man and the amendment of legislation to allow consideration of a licence to enable such an introduction.

During the period 16 March 2016 to 27 April 2016, the Isle of Man Government is seeking views from the public on a licensed introduction of red squirrels to the wild on the Isle of Man, which would require a change to Manx law. The Mammal Society has been invited to respond to the consultation by the Isle of Man Government.

The Mammal Society promotes the evidence-based conservation of British species.  It therefore has considerable interest in the proposal, and this statement is The Society’s response to the consultation document from the Department of Environment, Food and Agriculture of the Isle of Man Government[1].

The consultation poses three questions:

Q1. Do you agree with the removal of red squirrels from the Destructive Imported Animals Act 1963 and their addition to Schedules 5 and 8 of the Wildlife Act, thereby allowing their importation and providing for a licensing regime covering possession and release?

Q2. Should red squirrels be introduced to the Isle of Man?

Q3. If so, under what conditions?

This response focuses on Question 2, since the other questions become relevant only if question 2 were supported.

There is no evidence that red squirrels have ever lived on the Isle of Man. Thus the release of red squirrels to the island would be an introduction of a non-native species outside its natural range.  It would therefore be contrary to international agreements designed to avoid the profound ecological damage frequently generated by non-native invasive species.  The IUCN Species Survival Commission’s guidelines recognise two scenarios where intentional introductions may be justified: (a) assisted colonisation ‘to avoid extinction of the focal species’, and (b) ecological replacement to ‘perform a specific ecological function’.  The Mammal Society’s position is that neither scenario applies here.

With respect to the current status of red squirrels in Great Britain, and the potential ‘extinction of the focal species’ (IUCN scenario (a) above), recent research suggests that red squirrels will survive without intervention well into the next century in some parts of Britain. Considerable efforts are being made by conservation organisations and the public to conserve the red squirrel throughout its current range, and this work has stemmed the decline of red squirrels in many places such as Aberdeenshire, northern England and Wales. Furthermore, the spread of pine martens in Ireland and Scotland with the concomitant loss of grey squirrels and return of red squirrels reinforces the idea that the demise of red squirrels in Great Britain is some way off.  The current reinforcements of pine marten populations in Wales may also benefit red squirrel conservation.

With respect to establishing an island refuge to preserve British red squirrels, the consultation document raises the question “Can the British subspecies be sourced?”.   Although studies show there is some phylogenetic structure in Welsh and Cumbrian red squirrel populations, over the UK in general there is very little phylogenetic pattern and little evolutionary divergence between UK and other northern European populations, probably as a result of past introductions of red squirrels from continental Europe. Thus, there is no imperative to generate a new island refuge specifically for ‘British’ red squirrels. Furthermore, a number of red squirrel island refuges already exist, including Jersey, the Isle of Wight, Anglesey and Arran.

Based on these considerations, there are no scientific grounds or conservation value in introducing red squirrels to the Isle of Man and The Mammal Society does not support such an introduction.

References

Barratt, E., Gurnell, J., Malarky, G., Deaville, R., & Bruford, M. (1999) Genetic structure of fragmented populations of red squirrel (Sciurus vulgaris) in the UK. Molecular Ecology, 8, S55-S63.

Finnegan, L., Edwards, C., & Rochford, J. (2007) Origin of, and conservation units in, the Irish red squirrel ( Sciurus vulgaris ) population. Conservation Genetics, 9, 1099-1109.

Gurnell, J., Blackett, T., Butler, H., Lurz, P., Magris, L., & Shuttleworth, C. (2015) British red squirrel strongholds: challenges for conservation. In C. Shuttleworth, P. Lurz & M. Hayward (eds) Red Squirrels: Ecology, Conservation & Management in Europe, 211-232. European Squirrel Initiave.

Gurnell, J., Lurz, P. W. W., & BertoldiI, W. (2014) The changing patterns in the distribution of red and grey squirrels in the North of England and Scotland between 1991 and 2010 based on volunteer surveys. Hystrix, the Italian Journal of Mammalogy, 25: 83-89.

Hale, M., Lurz, P., & Wolff, K. (2004) Patterns of genetic diversity in the red squirrel (Sciurus vulgaris L.): footprints of biogeographic history and artificial introductions. Conservation Genetics, 5, 167-179.

Innes, J. B., Chiverrell, R. C., Blackford, J. J., Davey, P. J., Gonzalez, S., Rutherford, M. M., & Tomlinson, P. R. (2004) Earliest Holocene vegetation history and island biogeography of the Isle of Man, British Isles. Journal of Biogeography, 31: 761-772.

IUCN/SSC. (2013) Guidelines for Reintroductions and Other Conservation Translocations. IUCN Species Survival Commission, Gland Switzerland, viii+57 pp.

Lowe, V., & Gardiner, A. (1983) Is the British squirrel (Sciurus vulgaris leucorus Kerr) British? Mammal Review, 13, 57-67.

Ogden, R., Shuttleworth, C., McEwing, R., & Cesarini, S. (2005) Genetic management of the red squirrel, Sciurus vulgaris: a practical approach to regional conservation. Conservation Genetics, 6, 511-525.

Shuttleworth, C., Lurz, P. W., & Halliwell, E. (2015) Shared Experience of Red Squirrel Conservation Practice. 209 pp. European Squirrel Initiative, UK.

Shuttleworth, C., Lurz, P., & Hayward, M. (2015) Red Squirrels: Ecology, Conservation & Management in Europe. 328 pp. European Squirrel Initiative, Woodbridge, Suffolk UK.

Shuttleworth, C., Schuchert, P., Everest, D., McInnes, C., Rushton, S., Jackson, N., et al. (2015) Developing integrated and applied red squirrel conservation programmes: What lessons can Europe learn from a regional grey squirrel eradication programme in North Wales? In C. Shuttleworth, P. Lurz & M. Hayward (eds) Red Squirrels: Ecology, Conservation & Management in Europe, 233-250. Woodbridge, Suffolk UK, European Squirrel Initiative.

Sheehy, E., & Lawton, C. (2014) Population crash in an invasive species following the recovery of a native predator: the case of the American grey squirrel and the European pine marten in Ireland. Biodiversity and Conservation, 23, 753-774.

Vincent Wildlife Trust Pine Marten Recovery Project. http://www.pine-marten-recovery-project.org.uk/. Accessed 13 April 2016.

[1]  Accessed 11 April 2016 from https://www.gov.im/ConsultationDetail.gov?id=566