Monday, December 31, 2012

Of Mice and Voles (and men and molds)

Voles are adorable and horrifying creatures. When I forget them, it’s tempting to think that the ecosystem is mostly about plants. But when chocolate-brown meadow voles are eating every rare gentian every year, I’m forced to remember that ecosystems are equally animal.

There’s a comparison with you and me. Our bodies are ecosystems that include more bacterial cells than human cells. As microbes are to us - voles, insects, etc. are to the prairie. Venerable ecologist E.O. Wilson called them “the little things that run the world.” (In case you like numbers, each of our human bodies supports one hundred trillion bacteria, molds and other micro biota, most of which help us more than they hurt.)

We who seek to save prairies, woodlands and wetlands once thought that our mission was simply to restore nature, and then nature would take care of itself. As we explored restoration, successes unfolded like magic. Hundreds of (until recently) rare plant species eventually found their niches and became abundant, and the ecosystem grew progressively more diverse and healthy.

Animals (including some endangered ones) also voted their support. Rare butterflies, snakes and birds increased dramatically. When the first white-tailed deer returned to the North Branch, we felt we were seeing, in all our innocence, another confirmation that our prairies and woods were on the right track. By the time the deer had multiplied out of control and we started shooting them, conservationists considered them an easily understood exception. Deer may be nature, but they were wrecking the ecosystem because they lacked predators.

   The common meadow vole is promiscuous and barbaric. The similar but
   now-rare prairie vole is monogamous and territorial. Is there a clue 
   hiding in these rodents' morals?
Then came meadow voles. Why should they get out of balance? Somme Prairie Grove has a host of vole predators. Red-tailed hawks, great-horned owls, red foxes, and coyotes all feast so heavily on voles that these little rodents have been called “the hamburger of the grassland.”

Then rare plants started to vanish. For some species, when we caged them from the deer, the voles mowed down pretty much every one. Vole numbers follow a “boom and bust” cycle. Could we hope that their devastations were just temporary? But year after year it was the same thing, not just in the savanna but in the very high quality and original Somme Prairie as well. Tom Vanderpoel found the same thing at Grigsby Prairie twenty miles to the west.

   White-footed mice are common at Somme, but we never find them 
   wiping out a species. Why does this mouse “work well with others” 
   while the voles don’t?
Are some species populations being lost because of obscure out-of-balance species? Take the example of the globally-rare eared false foxglove (Tomanthera auriculata). This plant is an annual. It does not sprout again and get another chance next year if its reproduction is foiled. A seed bank may keep producing new plants for some seasons. But sooner or later the last seed will germinate, and the last plant will enter the bowels of a deer or vole, never to feel the sun on its chlorophyll again. At Somme, at least in some summers, the voles eat every foxglove.

We’ve invented “vole exclusion cages” to protect key plants. But there’s a limit to how many species we can protect that way. Every year, for example, every uncaged prairie gentian gets cut before the seeds mature.

What could be going wrong? Certain weasels and certain snakes feed heavily on voles. Those predators are missing at Somme. Should we work to restore them? That could be a compelling challenge! Are there vole diseases or insect pests or other controls that have vanished in these small and isolated sites? Who would study that?

When people, rather than ecosystems, have imbalances, we call it sickness. The fifth most common reason for people to take antibiotics is sinus disease. People with sinusitis on average have nine hundred species of bacteria up their noses. But people with healthy sinuses have more – twelve hundred species. This is another case where diversity is better than control. As Dr. Martin Blazer, chairman of the Department of Medicine at NYU said of human ‘germs,’ “Everyone focuses on the harm. And it’s not that simple, because without most of these organisms we could never survive.”

In ecosystem restoration we tend to restore one species at a time, usually by seeds. We could learn something from an earwax story that’s a favorite of Dr. Andrew Goldberg of U.C.S.F Medical Center. A patient had years of agony from an infection of his left year. He went through many doctors, who prescribed a variety of “antibiotics, anti-mold drops – the works.” Except that nothing did work. Then one day the patient came in smiling and happy.  Goldberg assumed he’d tried another medicine, but no. “I took some wax out of my good ear and put it into my bad ear, and in a few days I was fine,” the patient told him. This was human ecosystem restoration.

When we conservationists rescue a rare plant from the bulldozers at a prairie remnant and move it (and its dirt) to a site under restoration, we copy Dr. Goldberg’s patient. Tom Vanderpoel wondered how the rare Mead’s sedge got to the restored-from-scratch Grigsby Prairie. Then he noticed that each spreading clone of sedge had a hoary puccoon in the middle of it. Tom had rescued the puccoons from a high-quality remnant that was being destroyed. Unnoticed, the rare sedge came along for the ride. So, no doubt, did many species of bacteria, fungi, nematodes, and innumerable others. We don’t study the results of that sort of thing. We should. Not that it would be easy.

The medical quotes in this post are from Michael Specter’s “Germs Are Us – Bacteria make us sick. Do they also keep us alive?” in the October 22, 2012 New Yorker. There we learn that a person has about twenty-three thousand genes. Impressive?  Our human “microbiome” – the bacteria, molds, etc. that live on and in every part of us – has at least four million genes that help us in countless ways. Our bacteria outdo us, gene-wise.

Every plant and animal in the wild ecosystem has something comparable. That means Somme Prairie Grove has a lot of genes. Let’s see: 478 native species times four million genes, give or take a few, yields 1,912,000,000 genes for Somme Prairie Grove.
      For every plant species, a natural area is said to have ten animal species. 
      But then we have to add fungi, bacteria, and God-knows-how-many others. 

Oops, as Ronald Regan would say, there I go again. I forgot the animals. A “rule of thumb” guesstimates that for every plant species an ecosystem has about ten animals species (mostly small of course, but yet part of that petite elite that rules). Thus we compute that a natural area with 478 plant species (and 4,780 animal species) would boast a gene total of a bit over 19 trillion genes. That’s what we save when we’re good stewards. That’s what we lose if we let bulldozers or “the evil shade of buckthorn” eliminate the diversity.  

Next, I find my perspective flipped by Dr. David Relman, professor of microbiology and immunology at Stanford. I’ve long claimed that we need to see ecosystem stewardship as less like physics or chemistry – and more like human medicine. That is, we have to make many decisions based on best expert judgment – when we don’t have certain scientific fact. But Relman was speaking of human health care: “We have to stop looking at medicine as a war between invading pathogens and our bodies,” he said. “This sort of stewardship has more in common with park management than it does with our current practice of trying, in the broadest way possible, to kill microbes.”

Caring for our bodies is like ecosystem management? Well, of course it is. But here’s the implication for our forests, grasslands and aquatics: we have to learn as much as we can, make the best use of specialists (both ‘expert’ specialists and ‘local knowledge’ specialists), and then make the best use of generalists – to decide and act before it’s too late.

Among the Cook County forest preserves, most get no stewardship help, year after year. In the words of one ecologist, "County-wide (and no doubt region-wide) there are many good areas of rich diversity whose figurative fingers are sinking below the waves for the last time." 

That’s why many of us find it so rewarding to work (as volunteers or staff) at this pioneering quest. As one high-schooler said last week at the Solstice bonfire, “We need people winning Nobel prizes in this stuff.” Yes, we do. But some of the needed awards would fit better in the Peace Prize category than in any "hard" science. Conservation needs young new leaders who can span categories and invent ecosystem futures that work.


Anonymous said...


If you have not already seen it, I think you might like the following show.


Stephen Packard said...

The link James provides is to a Nova program where human starvation in some areas in India results when black rats, around rice fields, increase from 100 to 12,000 in a few months.
For this blog, that raises the comparison between plagues in simplified agricultural ecosystems compared to complex natural ones.
It would be great if some people would study the voles of Chicago Wilderness in the same way the Nova scientists studied eruptions in India.

Anonymous said...


I think all the diseases that voles historically possessed are still around. Also, most avian and mammal predators should be able to move into or out of Somme Prairie Grove. Although, the site might not be large enough to keep them around long enough for the predators to make an impact.

Since diseases and many predators are still present, I would work to introduce predators which are not likely to make their way to Somme Prairie Grove because of habitat fragmentation.

Do you have fox snakes at Somme Prairie Grove? If not I would try to get permission to introduce them from local sources. People are always calling to have them removed. It should not be difficult to obtain some for an introduction attempt.


Anonymous said...

Steve, years ago I was trapping rodents county-wide. The voles and white-footed mice we pulled out of your restoration were huge robust fur farm mice commpared to the normal mice in most preserves. I thought it was the superior nutrition they were getting from all the tasty seeds you scatter out there, or the plants produce. I mean turbo super rodents. So in some ways also a very high food supply can create abundance of the herbetores. Some good 'predators' - bott fly larvae, brain worms. like you said, the small things that steer the earth. (nice quote by the way).

Stephen Packard said...

I love the concept of "turbo super fur-farm mice." As we get more and more data on rodents, dragonflies, birds, etc. etc., it will be so very interesting to study the differences made by restoration, habitat size, fire history, etc. Thanks for bott fly lead - and the good comments generally.

Anonymous said...

Perhaps there is some plant missing from the enviroment that the mice and voles can be enticed to like better that the rare and endangered plants. Cherry tree farmers plant mulberry trees on the perimeter of their orchards because the birds will eat the mulberries before the cherries! What do mice and voles like better than gentians and foxglove! Plant some of those and the problem may go away! John Cherry, Jr,

Stephen Packard said...

I can easily imagine that a variant of John Cherry's suggestion is part of the solution. As we restore diversity, there's so much more variety of food to choose from. I notice that in some areas in winter the bark is eaten off most every shrub that isn't buckthorn, in part because 99% of the young woody plants are buckthorn. As we get more plum, hazel, Iowa crab, oak etc. etc. there's a lot more opportunity for the varmints to get fill before they've eaten all there is. Maybe some species will prove especially effective this way. I wonder how we find out which ones. We're very happy to plant a lot of food for the animals and still hope there's some left over to reproduce.

Anonymous said...

Among the Cook County forest preserves, most get no stewardship help, year after year. In the words of one ecologist, "County-wide...berry plants