The damage that grey squirrels can do to young trees has been widely documented and the different methods of control (principally shooting and trapping) have been widely debated. My observations in a small mixed woodland point to a silvicultural solution to the problems of squirrel damage to young trees.

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Nursery Wood was planted in 2008 with a wide variety of broadleaved trees with the object of creating a fully functioning woodland ecosystem. The particular part of the wood under discussion was planted with a band of mixed native shrubs on the edge. Inside the wood the main trees are pedunculate and sessile oak, ash, field maple and hazel with smaller amounts of alder, wild cherry and other species, all planted as an intimate mixture.

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In spring 2016 I noticed grey squirrels in a corner of the wood for the first time and shortly afterwards I noticed the first signs of bark stripping on some of the field maples. I was concerned that the squirrels would damage the oaks, my principal timber tree in this area, but I was unsuccessful in trapping or shooting any of them.

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By the end of the summer virtually all the field maple and some of the hornbeam in an area of about 0.2 hectares had been severely damaged but not a single tree of any other species had been touched. The field maple and hornbeam had been planted as understorey species to keep the trunks of the taller timber species in the shade, so I was not concerned about the bark stripping, in fact it was helping to stop the field maple from competing with the timber trees in the canopy. Had the presence of field maple, which is very susceptible to bark stripping, stopped the squirrels from attacking the oak trees? I will be watching this closely over the next few years to see if this pattern of preferential bark stripping is repeated.

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Current research has been devoted to more hitech solutions such as sterilising grey squirrels with a contraceptive pill and introducing pine martens to kill squirrels. A government website states that “the planting of “sacrificial” species in mixtures has not been shown to reduce damage to “high risk” species”. There is no reference to any studies which back up this rather sweeping statement.

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It is no help to woodland owners with squirrel problems in their existing woods, but all future woodland planting should have an intimate mixture of “sacrificial” species. There need be no loss of oak timber production from such mixed woods. The finest French oak woods have an understorey of hornbeam to keep the oak stems clean. Field maple could play the same role in Britain and keep squirrels away from the oaks as well.

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2023 Update. 7 years on and the young oaks in Nursery Wood are growing well and remain untouched by squirrel damage. At least once a week from March to June (the main bark stripping season) we walk the wood shooting squirrels with the help of a dog trained to bark at any tree with a squirrel in it. By June the foliage is too dense to see the squirrels. Between 2017 and 2021, 15-20 squirrels were shot each year. In recent years this has dropped to 0-5 squirrels annually. No damage has been seen on any oak trees and, since 2017, no damage on sacrificial trees either.

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2024 Update. I spoke too soon! in early July this year I suddenly realised that the squirrels were bark stripping again. This time it was in a different area of Nursery Wood and it was mainly hornbeam that was affected, with a few field maple as well. A quick check confirmed that damage was again confined to these 2 species. My precious oaks are untouched. We were particularly busy in the tree nursery this Spring and only shot 3 or 4 squirrels before leaf growth made shooting impossible. The trees are that much taller now and the squirrels are harder to locate. I had another look at one of the field maples that had been badly stripped back in 2017. It was still alive but had sparse foliage in the crown. It was still filling the understorey.

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2025 Update. It's easy to become complacent. In Spring 2025 we were very busy in the nursery. Our squirrel hunting dog's sense of smell is not as good as it was but she doesn't like to disappoint, so she started barking at random trees. Leaves flushed early in the warm Spring weather and by mid May we gave up searching for non -existent squirrels. We soon noticed fresh bark stripping on the field maple and hornbeam trees - by now most of the hornbeam and field maple in the wood had been damaged to some degree.

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On 8 June 2025 my worst fears were realised when I found 3 pedunculate oak trees with stripped bark in their crowns. We immediately destroyed 3 dreys which we had missed earlier and shot a squirrel in one of them. We also set 2 traps baited with peanut butter, but these had no visitors and at the end of June, when the bark stripping season had finished, we took them down.

Naturally, the squirrels had gone for the leading branches on the fastest growing oaks where the sap flow was greatest. These branches will die, but I am hopeful that the crown will survive and a new leader will be promoted.

The lesson I have learnt is that squirrels must be controlled and dreys destroyed in March, April and early May before the leaves have flushed. Any signs of fresh bark stripping on sacrificial trees should be followed up immediately.

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2026 Update. The wood was walked regularly during March and April but no squirrels seen. I returned from holiday on 24th May at the start of a heatwave with record May temperatures. There had been scarcely any rainfall since mid-March and everywhere was very dry. I was told that a squirrel had been seen in the wood. A day later I found the first bark stripping on hornbeam. Over the next week most of the hornbeam trees on the eastern side of Nursery Wood were stripped, some severely. I set up two Fenn traps baited with peanut butter. I caught 4 squirrels over the next 3 days. There is at least one more in the wood but they are wary about entering the box.

Grey squirrels strip bark so that they can get at the moist sap which they lick to quench their thirst. Placing your hand on a recently stripped tree you can feel the damp. Could it be that the drought had forced squirrels into the wood to find moisture under the bark of the 18 year old trees? If so, I was probably making them even thirstier by baiting my traps with peanut butter! I am now providing water in shallow trays throughout the wood for the squirrels and other wildlife. On 2nd of June we had our first significant rainfall, at last there is moisture in the wood. I am hoping that the squirrels will leave my trees alone.

For the last 3 years squirrels have been stripping the bark from the field maple and hornbeam in Nursery Wood, hardly a tree is untouched, some have been completely girdled. And yet none of these trees have died. Many have sparse foliage, but the field maple and hornbeam were planted to fill the understorey, not to provide timber. Bark has re-grown on the tree stems. 4 oak trees have suffered bark stripping high in the crown. Bark will not re-grow on oak trees so if the branch is completely girdled it will die.

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