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A review of the paper:
Spread and attempted eradication of the grey squirrel
(Sciurus carolinensis) in
Bertolino, S. and Genovesi, P. (2003)
Biological Conservation 109 pp 351-358.
The red squirrel (Sciurus
vulgaris) is a native European species. Another species, the grey squirrel
(Sciurus carolinensis) is native to
Fig 1: Grey squirrel (Sciurus carolinensis) and red squirrel (Sciurus vulgaris)
2: Grey squirrel damage to hornbeam and oak in
The red squirrel
is considered to be a threatened species in
Fig 3: Potential Expansion corridors
From: Bertolino & Genovesi, 2003.
discussed the attempted eradication of the grey squirrel after its introduction
The grey squirrel
population in northern
This consisted of a) monitoring of the grey squirrels’ range,
b) a trial eradication, and
c) eradication of the entire Piedmont population.
The trial eradication programme was to take place in an area of 170 ha, which was isolated from other populations by roads. The plan was sent to the main non-government organisations, including animal rights groups, for approval; and following this a ‘Panel of euthanasia’ plan was adopted as the most humane method. This plan was approved by government and non-government organisations and went into action in 1997. Trapping and euthanasia of the squirrels was effective in minimising stress to the animals, and in two trapping sessions over half of the population had been captured, with no accidental capture of other species.
The coordinator of the trial eradication and the director of the NWI were taken to court one month later by three animal rights groups, on charges of illegal hunting, damage to state property and cruelty to animals. This forced the programme to a halt while the case was on trial, which lasted for two and a half years. The directors were found guilty of illegal hunting and cruelty to animals.
During this time
the population of grey squirrels grew considerably, reaching the edge of the
It is predicted
that the grey squirrel could reach
The authors, working for the NWI, have presented a scheme to the Ministry of Environment for control of further expansion of the grey squirrel population, and protection of the red squirrel population. This scheme has been approved and will involve definition of key areas of conservation, local eradication in potential expansion corridors and re-introduction of the red squirrel into areas where it has disappeared (after removal of grey squirrels).
This paper highlights the difficulties of dealing with invasion by alien species, and the importance of fast action. The grey squirrels could potentially have been eradicated, but will now spread to the rest of the continent over the coming decades, posing a serious threat to the native red squirrel and its habitat.
S. and Genovesi, P. (2003). Spread and attempted eradication of the grey squirrel (Sciurus
Gurnell, J. & Pepper, H. 1993. A critical look at conserving the British red squirrel Sciurus vulgaris. Mammal Review, 23, 127–137.
Animal Behaviour, 61, 1079–1091
|Notes (if any) by Peter Kabai:|