Some non-native mammal species may be able to survive in our climate so could harm native wildlife if they are released or escape into the wild. It may be an offence to release a non-native animal, or allow it to escape, into the wild. Owners should follow the main Don't let them loose guidance, and additional guidance under Recommendations below to help prevent this from happening.

The following mammals are included on the list of species of special concern:

• Callosciurus erythraeus, Pallas’s squirrel
• Herpestes javanicus, Small Asian mongoose / Javan mongoose
• Muntiacus reevesi, Muntjac deer
• Myocastor coypus, Coypu
• Nasua nasua, Coati
• Nyctereutes procyonoides, Raccoon dog
• Ondatra zibethicus, Muskrat
• Procyon lotor, Raccoon
• Sciurus carolinensis, Grey squirrel
• Sciurus niger, Fox squirrel
• Tamias sibiricus, Siberian chipmunk

If you own one of these species there are other considerations that you must check here:

• England and Wales: Invasive non-native (alien) animal species: rules in England and Wales - GOV.UK
• Scotland: Legislation and responsibilities.

You should also check whether your animal is listed under other legislation, including:

• Destructive Imported Animals Act 1932 (mink, coypu and muskrats)
• Dangerous Wild Animals Act 1976.

Recommendations

• Consider neutering your animals, or keeping same sex populations, to prevent unwanted young.
• Use welded mesh enclosure fencing that is strong enough to withstand the weight of animals climbing on it or biting through it (minimum 14 gauge for predators) and has a mesh size small enough to prevent the animals becoming entangled or escaping (2.5 cm x 2.5 cm or finer).
• Secure the enclosure with a key operated lock as some mammals learn by observation and have a high level of dexterity so may learn to undo bolts and other closure devices.
• Install a buried wire “skirting” fitted at a 90o angle to the vertical fencing inside the enclosure, to prevent animals from tunnelling out.
• Ensure enclosures have a secure roof.
• Install a double-door entry with a space of approximately 2 m2 separating the two doors - one should always be closed before the other door is opened.
• Check enclosures daily for damage and proactively remove overhanging branches etc that may cause damage. 
• If you bring your animal into the house, make sure external doors are locked, windows are closed or protected with mesh to prevent escape, and your animal is not left unattended - some can learn to turn keys and work door handles.
• If you need to take your animal to the vets, or to boarding accommodation while you are on holiday, ensure it is transported in a container that it cannot escape from, for example, raccoons and other procyonid species should be transported in a locked wire or plastic cat carrier.
• Think about what would happen to your animal in the event of an emergency such as a flood or fire - what equipment would you need to hand to safely evacuate your animal?
• Plan for if your animal escapes - what steps would you take to recover them? See what to do if your pet escapes for guidance. 
• Follow the Don’t let them loose guidance on what to do if you can no longer keep your pet.