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.

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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