Advice
RHS Help & Advice
Grey squirrel (Sciurus carolinensis)
Plants affected
A wide range of ornamental plants, fruits and vegetables are affected. Particularly at risk are tulip bulbs, crocus corms, maize/sweet corn, strawberries, apples, pears, nuts, sunflower seed heads and flower buds of camellias and magnolias (see picture right). Trees, including sycamore, maples and beech, can be badly damaged by bark stripping. Lawns can be damaged when squirrels bury or dig up winter food stores.
Biology
The grey squirrel originates from North America and was introduced into Britain during the 19th century. It is now found throughout most of Britain and has largely replaced the native red squirrel (Sciurus vulgaris). Grey squirrels can produce two litters a year, which are raised in nest-like structures called dreys. Young are generally produced in February and July; a typical litter size is three or four. Grey squirrels are active throughout the year on all but the coldest days. In addition to eating fruits, nuts, seeds, flower buds, bulbs and corms, vegetables and bark, grey squirrels will raid bird feeders and take eggs from birds’ nests.
Bark stripping appears to be associated with stress brought on by territorial disputes. It is more likely to happen when squirrel numbers are high and there is increased competition for territories. When the bark has been lost from all or most of the circumference of a branch or trunk, it is likely that the growth beyond that point will dry up and die.
Damage prevention
It is not possible to stop squirrels from coming into a garden. Placing netting over plants that are being damaged may be of little help unless wire netting is used. Animal repellent substances and scaring devices are likely to give no more than short-term protection.
There are no poisons approved for use against grey squirrels in gardens. It is permissible to control grey squirrels by shooting or trapping, provided this is done in a humane manner, but shooting may not be feasible in gardens for safety reasons. Traps are available from some garden centres or mail order companies. The most widely used is a cage-type trap that will capture squirrels alive. Such traps can be baited with peanuts and must be checked at least once every 24 hours, preferably morning and evening. Under the Wildlife and Countryside Act it is illegal to release non-indigenous animals into the wild, so any grey squirrels caught should be killed. This can be done by shooting or allowing the squirrel to escape into a sack, where it can be held while a sharp blow is delivered to its head. Drowning squirrels by putting the trap in a water butt is not a humane method of dispatching squirrels. More squirrels are likely to move in to occupy the vacated territory, so a garden is unlikely to be squirrel-free for long.