Controlling grey squirrels will save our trees.

Planting a tree, watching it grow for 10 to 15 years then having the trunk, large branches or occasionally the whole tree die off because of squirrel damage is frustrating. This is reason enough to want to control squirrels, and that’s before we consider their contribution to the demise of the red squirrel, their threat to dormouse populations through competition for food, and that they raid the nests of woodland birds.

Tree damage will happen every year if we don’t take action, and hardwoods are at risk for a considerable length of time. Damage can start about 10 years after planting when the branches of the trees are strong enough to hold the weight of an adult squirrel, and can carry on until the bark becomes too tough for them to eat, which won’t be until the trees are 35 to 40 years old.

As squirrels have two litters per year, one in spring and one in late summer, a few left alone at the start of the year will have become a great deal more numerous by the autumn. It?s in summer that the damage is done, when the trees put on a growth spurt and the flow of sap is at its highest. There is, therefore, a particular risk where trees have been thinned out as the thinning process promotes growth among the trees that are left.

Drey poking is rather time-consuming and a lot of the squirrels on our land nest in holes in large parkland trees where we can’t get at them anyway. Picking the odd one off with a gun is quite fun and can only help, but if you really want to reduce numbers there are only two serious options: trapping and using poison hoppers.

A choice of traps

Being inquisitive, squirrels are quite easy to trap either in tunnels or cage traps. I prefer the former to the latter as with a tunnel trap the squirrel is always dead when you find it, which makes it easier and quicker to reset the trap. Also, you don’t need to pre-bait, carry bait or have a priest with you to kill anything you’ve caught. As we own a large area of woodland and don’t always have the time to set traps throughout it simultaneously, we make tunnels out of wooden planks, nail Fenn traps to the side of each, then set them in a given area for a couple of weeks before moving them on to the next. It saves a lot of time compared with making permanent tunnels as you would if you were trapping stoats, and the squirrels use them from day one.

The Kania trap is relatively new on the market and is attached to trees. Though it needs baiting it does have an advantage over tunnels in areas where there are animals and children: a Fenn trap might catch unwary fingers, or a family pet might destroy the tunnel to get at the trapped animal. These things will not happen with a trap set 5ft up a tree.

Poison hoppers

Poison hoppers may seem a little lazy, but if you’ve got lots of squirrels, large areas of woodland and limited time, they really are the best solution. They only need checking once a week if you have a sufficient number of hoppers to cover the area you want to protect. We place a hopper every four to five acres in young plantations and every 15 to 20 acres in mature woodland. Once they’re out, filling them takes no time at all. With poisoning you find few bodies because the squirrels die in their dreys or in the boles of trees where you can’t see them. If you do happen to find a carcase, dispose of it as you would a poisoned rat. Where there are a lot of badgers or deer, place the hoppers a metre off the ground – the squirrels will still find them, and as long as you can reach the lid they’re not much harder to fill.

There are, however, a few things that need checking before you start so as to make sure you stay within the law. Hoppers can only be used in certain counties; if your county has red squirrels or pine martens then using them is against the law. You can use them in areas with dormice but there has to be a weighted or magnetic flap inside the hopper, which stops the dormice getting to the bait (but not the squirrels). They can only be used between 15 March and 15 August, can only be filled with approved warfarin-based poison and the person using them has to hold a certificate of competence in vertebrate pest control.

We don’t bother with pre-baiting and fill our hoppers with warfarin straight away. What we find is that the hoppers empty slowly for the first week, quickly for the second and third weeks and then usually stop being used by week four. In about a month, which appears to be the time it takes for new squirrels to re-colonise, it’ll start all over again.