Up the chain: trophic system moderators

“What limits size and growth?……..

We ourselves are part of a guild of species that lie within and without our bodies….. Most of nature is composed of groups of species working interdependantly, and this complexity too must have its synchronistic regulators.”

-Bill Mollison Permaculture: A Designers Manual

Rummaged potting soil and dried, dead little seedling roots dangling in the air was a recurring sight in our greenhouse a couple years ago. Whole flats of peppers would have their tops nipped off and the like because of mice.

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Our heated greenhouse.

Poisons, traps, and even some nasty sticky pads lined the floors waiting to dole out death to the offenders, but they were ineffective. The traps caught few mice. The destruction continued. The sticky pads outside our sprouting room caught sparrows which I had a hard time cleaning the nasty goo off trying to save. Nothing worked until we got a cat.

Esmerelda is a small, long haired drop-off cat, but is the best mouser I have ever seen. For a while after she showed up, I would regularly pass her walking up the driveway with a fat vole in her mouth. As I raked out last season’s growth in the greenhouse, her face would be stuffed right in the middle off my work, waiting for a vole to dash from its dinner table.

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Esmerelda and Niki

Now when we plant, the only thing mice bother is fresh squash seeds, but even those are seldom touched. Having made some hanging shelves to keep the squash seeds out of reach, it’s difficult to tell if we have mice or voles at all.

Making friends with rodents is recognizing what voles, mice, and many of the technically-not-rodents like rabbits and ground hogs do for our plants I explained in the earlier post. It also means keeping their numbers in proportion to the rest of the ecology. Artificial trophic system moderators, such as traps and poison, aren’t that effective. What is effective, is encouraging these rodents’ predators.

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Perched Niki

As a USDA Certified Organic farm, we actually have to submit a written explanation of how we manage trophic levels such as rodent population, and Esmerelda is officially accepted as part of that system.

Owls are major predators of mice and other smaller rodents. Barn owls, which have species across the globe, eat at least one rodent a night. A pair with young captures as much as 3000 per year according to some sources, which would certainly keep about any rodent population in check.

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One of the many subtly varied species of barn owls. Photo by Jim Vallee

Barn owls are fairly ubiquitous, so the chances of hosting a pair is pretty likely if you have old buildings, hollow trees, or nest boxes where they can raise their young.

In addition to preying on mice, larger species of owls can prey on rabbits. We have a pair of great horned owl on our farm, which we likely wouldn’t have known about if it weren’t for the faint sunlight betraying one of their silhouettes as it ghosted off one evening. We had some young pullets at the time the owl’s were picking off once a day at dusk. The remedy was caging up the pullets earlier in the evening and letting the owls go eat the mice and rabbits.

With this kind of appetite and stealth, great horned owls can obviously carry away some rabbits. Studies have shown even these big owls though also like mice, and that a pair will catch up to a dozen a night when feeding young.

Dogs have a pretty broad array of prey. Foxes prey on mice and rabbits. Larger animals like coyotes can prey on groundhogs, but few of us want those close to our gardens and homes. This is why we domesticated them.

We have a rat terrier, named Daisy -named after the bee bee gun brand. We got her specifically for managing the rodent population, which she does very well. Despite her small size, she also gets possum and groundhogs. This is because we’ve carefully trained her.

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Daisy hoping to get a bite of that pea. She loves veggies.

We have adhered to the idea that dogs seldom hunt alone, almost always in packs, with one taking the attention, others lunging in for the kill. Daisy has always been taught that if she finds something, we will always come to her aid. If she finds a mouse under something, she barks, we come, and do what we can to move things around and let her get at it.

This is especially important when she beats a very large groundhog to its hole and lays into them. She kills her prey by lifting it off the ground and giving it a whip, snapping it’s neck. As a result groundhogs larger than her are pretty much impossible for her to kill alone. She has always been taught that someone will show up shortly to make the final blow while she keeps it’s attention. She can handle young groundhogs herself.

Our neighbor had a much larger dog they would keep in their fenced garden area at night when the sweet corn was about ripe. This kept raccoons from pillaging the place.

Some might object that allowing an animal to kill anything makes them a threat to their human caretakers. I think this is more a matter of teaching the dog who is a friend, who is a foe, who is above them, and who is below them. This sounds petty among us humans who obviously function differently, but this is how dogs work. Even with animals that could and should be prey for Daisy, we have trained her to not kill.

If our rabbits get out for instance, we sic her on them. She catches them by simply holding them until we come pick them up. She doesn’t pick them up and snap their neck as is her method to kill anything else. The rabbit is a bit slobbered-on after this, but in my experience, catching rabbits alone is seldom less stressful for the rabbit, usually unsuccessful, and simply leaves the rabbit prone to being eaten by a raccoon -because they certainly don’t care about a rabbits quality of life.

In general, I think cats and dogs enjoy a much better quality of life when they are allowed to express their instincts. If we can figure out a way they can do this without endangering us, this is a mutually beneficial relationship.

Across the board, effective ecology creation means making friends with your pests. Sometimes, keeping a balance means making friends with their predators.

3 thoughts on “Up the chain: trophic system moderators”

  1. Hurray for cats and dogs – and your owls of course. We don’t have the same level of pests here but a neighbouring cat certainly takes care of the mice in my garden.

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