Invasive Alien Species Order 2019, letter to MPs

In the run-up to Christmas rescue centres throughout the country who help injured and orphaned wildlife were shocked to receive an email from Natural England stating that their licences to keep and release grey squirrels and muntjac deer are being revoked under the new Invasive Alien Species Order 2019 (1).

From April this year it will be illegal to help these animals, and vets and rescue centre staff will have to either turn away or euthanise them, in the full knowledge that they can easily be helped and returned to the wild, where they came from.

The effects of this law are easy to predict: animals will suffer unnecessarily, compassionate members of the public who find the animals in need will suffer great stress when they realize that there in no rescue pathway available, veterinary surgery and rescue centre staff will be traumatized and demoralized. Inevitably, many small-time rescuers will go underground as a matter of civil disobedience, which mean that the law will be impossible to enforce.

We would therefore like wildlife rescue to be made exempt from the Invasive Alien Species Order 2019.

The Order is based on EU Regulation 1143/2014 (2). There do not appear to be any changes of substance, it merely substitutes “appropriate authority” for “member state”. As such, we note that the EU regulation makes special provisions for cases where the species is already well established in the country. There is no need to aim for eradication, merely control. It is also up to the member states (now appropriate authorities) to determine the risk and choose the method of control, which can be non-lethal (3).

The current interpretation of the text, the interpretation that results in making rescue illegal, is excessively harsh. Rescuing grey squirrels and muntjac deer presents no risk to their habitat, rescue numbers are simply too small for that.

Furthermore, the actual ecological impact of these species needs to be re-examined. They are sometimes disliked purely because they are an introduced species who “do not belong here”. To justify what is essentially a prejudice, they are regularly accused of various crimes against the eco-system, but these accusations need to be investigated properly if they are to form the basis of legislation.

Grey squirrels are an example of a species whose ecological impact has upon occasion been misrepresented to the public. Grey squirrels do not reduce the bird population (4) and the tree damage in commercial forestry is statistically acceptable (5).

As far as their relationship with “native red squirrels” is concerned, we understand that ecological replacement is a complicated issue, but the following points have to be considered in order for the decision-making to be evidence-based and balanced:

  1. Red squirrels are not an endangered species, their conservation status is “least concern”; they are abundant in the rest of the world, wherever the habitat is suitable for them; because of deforestation the UK cannot, for the most part, offer them a suitable habitat;
  2. Because of habitat loss red squirrel numbers declined to the point of extinction by the end of the 18th century, before the greys were introduced (6);
  3. Red squirrels were themselves then reintroduced from Scandinavia, so in that sense they are not exactly “native” either (7);
  4. In areas where the habitat is exactly right for red squirrels, they coexist with the greys (8);
  5. Having descended from limited genetic stock (9), red squirrels succumb to many diseases, the pox that grey squirrels carry is only one of them, and not a major factor, statistically, in red squirrel mortality (10).

If, in spite of the above, the need is felt to control grey squirrel numbers, we suggest that it is best done by non-lethal means, such as limiting food availability (the supplementary feeding of game birds bred for the shooting industry swells up grey squirrel numbers) and the development of oral contraceptive Gonacon, now underway in Defra laboratories


1-  (accessed 24/12/2018)

2 –  (accessed 15/01/2019)

3 –  (accessed 15/01/2019)

4 – (accessed 13/07/2018)

5 –$file/fcpn004.pdf (accessed 13/07/2018)

6 – Harris, et al., ‘Is culling of grey squirrels a viable tactic to conserve red squirrel populations?’, Bristol University, 2008.

Middleton, The Ecology of the American Grey Squirrel in the British Isles, 1930.

7 – Hale, et al., ‘Patterns of genetic diversity in the red squirrel (Sciurus vulgaris L.): Footprints of

biogeographic history and artificial introductions.’, University of Newcastle, 2003.

8 – Bryce et al., ‘Can niche use in red and grey squirrels offer clues for their apparent coexistence?’, Journal of Applied Ecology, 2002.

9 – file:///C:/Users/natal/Pictures/Squirrels%202017/Red%20squirrels%20genetics.pdf  (accessed 15/01/2019)

10 – Simpson et al., ‘Causes of mortality and pathological lesions observed post-mortem in res squirrels (Sciurus vulgaris) in Great Britain’, BMC Veterinary Research, 2013.