Yep as Darren said - and I know I do go on about it! - but bark stripping by grey squirrel isn't primarily a feeding behaviour, it's now thought to be a essentially territorial marking and follows antagonistic interactions between individuals.
It's true that at the time of year stripping mainly occurs there is little of what is perceived as 'squirrel food' about (i.e. nuts and seeds) but they eat buds and insects too, so no they're not particularly hungry or short of food. If it was related to food shortages then of course the simple answer would be to provide them with a food supply - a few cheap sacks of wheat or barley dished out at intervals into feeders and the problem would be solved. Don't be tempted to try it! It causes an increase in bark stripping. Squirrels flock in for the easy food, so you get a high density of indivduals, which means they come into contact with each other more frequently - so more interactions and more stand offs followed by both going off and bark stripping.
There isn't always the need for control though. Sweet chestnut can heal very dramatic squirrel damage (assuming it's not all the way around the stem)and if the tree is destined for firewood or just going to be allowed to grow out its natural life then why bother? If you're growing for timber then squirrel control just can't be avoided.
The Kania traps are expensive but built to last and very effective (and I believe humane). Definitely Slow cooking is best (we like them with rosemary), but also cajun style!
This might sound grim but if you go through a lot of squirrels in a year it's very good!
Squirrel liver pate (modified from Anthony Worrel Thompson)
Keep a large reseable feezer bag in the freezer add the squirrel livers to it over the season as you go!
Ingredients
175g/6oz unsalted butter, softened
40-50 squirrel livers, trimmed and cleaned (defrosted) (you could make up the difference with rabbit or chicken if you don't have enough squirrel approx. 450grams needed- but squirrel IS better!)
2 shallots, finely chopped
1 tsp soft thyme leaves
2 cloves garlic, finely chopped
2 tbsp brandy
2 tsp anchovy essence
½ tsp freshly ground black pepper
55g/2oz clarified butter, melted
Preparation method
Heat 15g/½oz of the butter in a frying pan until foaming.
Add half the livers and fry quickly on all sides until golden, but still pink in the middle, about 4-5 minutes.
Repeat with a second batch of butter and livers.
Place the livers and juices in a food processor.
In the same pan heat another 15g/½oz butter, add the shallot, thyme and garlic, and cook over a moderate heat until the shallot is soft but not coloured.
Add the brandy, anchovy essence and pepper, and scrape the bottom of the pan to release any coagulated juices.
Place everything in the food processor, including the remaining unsalted butter. Blend until smooth.
If you want a very smooth pâté, pass the mixture through a fine sieve and put in a bowl. Cover with the cling film, cool then refrigerate. If not using within 48 hours, cover the top with clarified butter.
