Photographs: Charles Francis
November 2017: A broadleaved woodland at the Trewithen Estate was in fine shape until it was destroyed by a gang of grey squirrels, not much more than a decade after it was planted. The loss of the wood, which covered almost four acres, led to Trewithen becoming a breeding site for red squirrels, the native species which has disappeared from much of Britain because of competition for food and habitat from North American greys.
Grey squirrels are notorious for stripping trees of bark to gain access to the sweet sap beneath. Removal of the phloem tissues which contain the sap causes restricted growth, fungal infection and often death.
Woodlands like the one at Trewithen are at the greatest risk, because the squirrels like to feast on the sap of trees between ten and 40 years old. “Grey squirrels don’t go for saplings, as young trees can’t support their weight, and they don’t like older trees because the bark is too thick,” explains Natasha Collings, co-ordinator of the Cornwall Red Squirrel Project, which aims to reintroduce the animals to the county after removing greys from selected areas. “Red squirrels don’t do wholesale trashing of trees.”
The period between April and July is the peak time for the greys’ bark-stripping activities. Their favourite trees to feast on are sycamore, beech, oak, sweet chestnut, pine, larch and Norway spruce, says Natasha, but almost any broadleaved species of tree can be attacked.
Damage caused by grey squirrels to a young maple tree
At Tehidy Country Park, near Camborne, an unseasonal early summer storm several years ago resulted in many sycamores having their tops blown off because they had been too badly damaged by grey squirrels to cope with wind and rain. Attacks by the creatures at the National Trust’s Trelissick Garden mean that stunted and weakened trees have to be removed regularly to prevent them falling onto footpaths during episodes of wild weather. There are similar challenges at the Trelowarren Estate on the Lizard. Landowner Sir Ferrers Vyvyan says: “Grey squirrels ring mark the bark of trees, and they can go all the way round a small tree within minutes and destroy it”.
The grey squirrel is larger than the red, and is in the top 100 of the world’s most invasive species. There are around five million in the UK, and only about 120,000 reds, three-quarters of which are in Scotland. They cause over £50 million per year to commercial forestry, and unquantified havoc in gardens, woodlands and public parks. The red squirrel is now one of the most threatened species of mammal in the country, and was last seen in the wild in Cornwall in the mid-1980s.
The Cornwall Red Squirrel Project was set up in 2009 by some of the county’s major landowners, including Sir Ferrers, Charles Williams of Caerhays and Michael Galsworthy of Trewithen — who remembers seeing red squirrels scampering across his lawn 60 years ago — and the Duchy of Cornwall: Prince Charles has taken a personal interest in the project. With the assistance of Dr Craig Shuttleworth from the highly-successful Anglesey Red Squirrel Project, a habitat survey was carried out on the Lizard and West Penwith, after which a decision was made to focus on the Lizard, where ten per cent of the land is woodland.
Three grey squirrel trappers are now at work on the peninsula, recording the sex and weight of each squirrel and whether it is an adult or juvenile, and taking tissue samples to test for squirrel pox, which is fatal to red squirrels.
“We communicate with organisations like Natural England, the National Trust, Cornwall Council and the Forestry Commission through our stakeholder group, so we can demonstrate that we’re following the international guidelines on the reintroduction; one is that the habitat has to be suitable,” says Natasha. “We also receive scientific and technical support from the Red Squirrel Survival Trust and the Game and Wildlife Conservation Trust.”
She emphasises that the project is privately funded, mostly through a membership scheme and donations, and all money raised is ploughed back into its work. Public reaction to the grey squirrel cull is generally positive. “In six years, I have had only about ten complaints, and they were mostly from people who didn’t realise that grey squirrels are not native and that they damage trees, and also predate the eggs of woodland birds.
“What we’re hoping in the next two years is that we will be pushing down on the grey squirrel population so we can think about releasing reds. The release strategy is due to be finalised at the end of the year.”
In the meantime, the breeding programme is proceeding well. Paradise Park at Hayle is part of the national studbook for red squirrels, and matches pairs which are genetically different from each other. The park was already working with the Anglesey scheme before becoming involved with the Cornwall Red Squirrel Project around five years ago.
Curator David Woolcock says: “We have bred 80 or 90 red squirrels in the last 20 years, and the vast majority have been sent to Anglesey to be released. We slowed down the breeding programme for a while, because they were doing so well in the wild. But eight to ten breeding groups will be needed to supply sufficient numbers for them to be released in Cornwall, so we’ve been encouraging gardens like Trewithen and Trelowarren to become satellite breeding centres. We’re looking forward to seeing red squirrels back in the county — but we have a duty of care to make sure they will be as safe as they can be from greys and squirrel pox before they are released.”
Red squirrels eat the seeds, buds, flowers and shoots of both deciduous and coniferous trees, along with fruits, berries, caterpillars and fungi. “They don’t like acorns much, because they can’t cope with the high tannin content,” says Natasha. “And as far as we know, unlike greys, they don’t dig up bulbs — something gardeners don’t like — because they’re arboreal.”
The Cornwall Red Squirrel Project’s advice for gardeners in Cornwall who are interested in planting red squirrel-friendly trees in readiness for their release is to choose elder, hazel, walnut or sweet chestnut.
Sir Ferrers Vyvyan points out that 50 per cent of the Trelowarren Estate is mixed woodland, and it has been assessed as the perfect red squirrel habitat. “There were red squirrels at Trelowarren within the living memory of the community,” he says. “We are very excited about the prospect of bringing them back here.”