Blurring gray fur and tails pour like a waterfall onto the floor in front of me. A tense minute, and the place is cleared -bare, clean cement floor, and nothing but hushed scurrying sounds all around. I’d just turned on the light.
This was one summer long ago, when several old building were torn down by the Township very near our chicken house. These were an old garage, another chicken pen near it, and a large old barn. They all housed droves of rats. Where did they go when these building fell? Our place.
We had quite a clean operation. When the rats came, we cleaned it to the max, removed all the wood shavings, straw bales, any and all feed -no matter how tight its container, and even some of the chickens. Despite the cleanup, the invasion lasted for months.
They were too smart to fall for traps. Eerily, one of the traps we found set off with no rat in it, had a freshly gnawed twig from the lilac bush right outside the pen stuck in it, the bait removed. My dad stayed up several nights shooting them with pellet guns. He terminated the lives of hundreds, but only recovered a few because the rats began eating their fallen, dragging them back into their holes immediately, or gnawing into them on the spot. To say nothing of a few unfortunate chickens that fell prey when the lights went out.
The rats made this new house their home in short order -with or without resources. They dug enormous piles of soil out from under the cement flooring, brought in food from some place. We had removed everything else.
When specialists begin throwing out statements about harshly mowing orchards to keep rodent and rabbit from gnawing away bark and roots of trees, I am a bit skeptical. These creatures create habitat for themselves and are part of thriving ecologies. They are eaten by almost everything, providing a vital link in the trophic system. If you have ever studied how these systems work, reducing one part of the chain, reduces, or at least effects, all the others following. If you reduce rodents, you by default reduce potential health of the trees you’re trying to protect.
Rodents feed into a very broad system. Finding examples of what happens when rodents are entirely removed is difficult because we have seldom pulled this off in outdoor settings. If we have come close, someone is also fertilizing and pruning a lot to make up for the loss.
Rodents have many immediate effects too. For one, they dig holes, which allow more air and water to percolate into the soil. This is very good for soil health.
It’s interesting to note the trees most immune to damage by rabbits, voles, etc. are single seeded species, like peach and plum. The species most vulnerable are multi-seeded species, like apple and pear. Rodents and rabbits, every couple of years when the food gets scarce, devour the bark off a couple of these trees, killing the trees. If they didn’t these multiseeded species have a higher chance of sprouting on top of each other, and choking each other out.
Only one successful seed is necessary to replace its parent. Rodents are a factor which ensures the chance any young tree grows to adulthood is very, very low. This is a good thing in natural conditions. It means trees are more likely to be well spaced.
But how do we make our tree “the one” that grows to adulthood when we’ve already taken spacing into account?
The most effective move is just installing tree guards; simple spiral guards are fine for young trees; tree guards like these are better for larger trees. Larger trees are less vulnerable to girdling, but I have seen trunks near five inches in diameter girdled to the hard wood if the snow lays thick enough long enough. For these sizes, I am not a fan of corrugated plastic pipe guards because they’re extremely hard to get on and off, often harming the tree in the process. Even covering the trunks with tinfoil or fine wire mesh is better than nothing.
Opaque tree guards also protect from sun scald: when bright sun reflecting off cold snow heats the cold tree bark, making it crack. This isn’t good. Covering the trunk helps prevent it.
Another tactic is to provide food for the rodents (No, I’m not nuts. Keep reading). The fact is, rodents and rabbits will be present whether you like them or not. If you mow the grass, they will dig tunnels. If you remove food, they will find it, and store it.
I’m not the only one recommending this. One extension service informational pamphlet extolled mowing the grass in an orchard to the finest bits to reduce cover, yet recommended throwing out sunflower seeds when the snow fell. This is intended to divert the eminent population of rabbits, voles, and mice -now forced into starvation.
Apparently the specialists are aware their mowing and trapping are only mildly effective, and that the real issue is diverting and blocking the rodents when times get tough, not killing them. Natural predators do that.
It seems most logical to just leave the tall grass and brush -at least in isolated corners, so the rodents can feed themselves.
There are also biological deterrants, such as Sepp Holzer’s bone tar. Here is a forum discussion on the subject. Sepp Holzer explains making bone tar and its use in his book. I own a copy, and quite like it. I have never gone through the trouble of making bone tar though. Tree guards have done the job for me.
There is an idea that planting certain bulbs and other plants around a tree deter rodents and rabbits -especially voles, which eat roots underground. In controlled studies, ground covers like Pachysandra species, and bulbs like daffodils are themselves very unpalatable to rodents. This doesn’t necessarily deter their cozying up to your trees.
I’ve had trees with no guard brutally stripped by rabbits, despite a ring of daffodils around it. Keep in mind, when hunger gnaws, rodents gnaw just about anything -tasty or not. While these plants might deter voles from eating roots, don’t expect these to block the possibility of girdling.
Ecosystems keep a pretty tight control on rodents and rabbits as is. If we simply focus on making a healthy, lush habitat, giving your trees the protection to make them “the one” that succeeds in growing to adulthood, the rodents can function less as your foes and more as your friends. The alternative is certainly not as pretty.