Monthly Archives: July 2014

The Common Good

Human society appears to thrive best when the governments of the day are guided by the common good. But what is the common good and how can we determine what actions are consistent with it? These are most difficult questions and the most controversial issues of the day involve human rights and obligations over issues like abortion rights. But the common good also describes many problems that are environmental, and ecologists have a right to assert the common good from their collective knowledge of how biodiversity operates to sustain life.

The common good is any action that benefits society as a whole, in contrast to benefiting the private good of individuals, sections of society, and corporations. It is a worthwhile exercise to look at the controversies and decisions made by governments in our time and judge whether they pass the litmus test of the common good. Just this week for example, the Canadian government has promoted regulations restricting the use of antibiotics in meat and poultry production because current indiscriminate use invites antibiotic resistance in bacteria that cause human diseases. Such a decision is a cost to livestock producers but a benefit to society. Since microbial ecologists have been suggesting such a restriction for more than 25 years, the only question left is why the common good was set aside of all these years.

The common good looks to the future while many of our governments do not. Climate change is an issue that ecologists have been discussing for more than 20 years with virtually no action from our governments, much talk, little action. In British Columbia at the moment there is a discussion about damming the Peace River at Site C for hydroelectricity. The justification for this is the common good that a growing population in BC will need more electricity, and this is pollution free electricity, what many ecologists have been requesting. But the price of this is a loss of good farmland and the disruption of river food chains. Is this plan to build a dam at Site C consistent with the common good? It might be if there is no alternative to the dam, and if indeed the power generated is for the people of BC rather than for mining companies that taxpayers subsidise. Would not the common good be better served by conservation of electricity use, the development of solar power, geothermal power, or wind power?

Conservation of biodiversity is a clear public issue where the common good is obvious. Implicit in the concept of the common good is the assumption that we will not take actions that imperil the future for our children and grandchildren. In conservation decision making ecologists play only a small role at present, but this was not always the case. Someone had the foresight to set aside parks and reserves long before ecology was taught in the schools, and governments at least appeared to operate for the common good. But now we see tendencies to define the common good as more export dollars for coal and gas and oil, so that pipelines can be permitted in national parks and reserves with few questions asked.

Money talks but people vote, and consequently it would be useful for ecologists as well as ordinary citizens to demand that our society define and follow the common good rather than the generation of wealth for the few and nothing for future generations.

Everard, M., B. Pontin, T. Appleby, C. Staddon, E. T. Hayes, J. H. Barnes, and J. W. S. Longhurst. 2013. Air as a common good. Environmental Science & Policy 33:354-368.

Sandel, M. J. 2012. What Money Can’t Buy: The Moral Limits of Markets. Farrar, Straus and Giroux, New York. 244 pp.

Sargent, R.-M. 2012. From Bacon to Banks: The vision and the realities of pursuing science for the common good. Studies in History and Philosophy of Science Part A 43:82-90.

Vineis, P. 2014. Public health and the common good. Journal of Epidemiology and Community Health 68:97-100.

The Snowshoe Hare 10-year Cycle – A Cautionary Tale

We have been working on the ten-year cycle of snowshoe hares (Lepus americanus) in the southwest Yukon since 1975 trying to answer the simple question of what causes these cyclic fluctuations. I think that we now understand the causes of the cyclic dynamics, which is not to say all things are known but the broad picture is complete. But some misunderstanding persists, hence this one page summary. Some biology first.

The snowshoe hare cycle has been known from Canada lynx fur return data for more than 100 years, and of course known to First Nations people much before that. Hares are herbivores of small trees and shrubs, they reproduce at age 1 and rarely live more than 1-2 years. They have 2-4 litters in a summer, with litter size around 4-6. Juvenile losses are high and at best populations increase about three-to-four-fold per year. Almost everything eats them – lynx, coyotes, great-horned owls, goshawks, a long list of predators on the young. Reproduction collapses with rising density and females reduce their output from 4 litters to 2 in the peak and decline phase.

The obvious driving factors when Lloyd Keith and his students began working on the hare cycle in Alberta in the 1960s were winter food shortage and predation. When there is a high hare peak, damage to shrubs and small trees is obvious. But it was quite clear in Keith’s studies that the decline phase continued well after the vegetation recovered, and so he postulated a two-factor explanation, winter food shortage followed by high predation losses. He looked for disease and parasite problems in hares but found nothing.

Testing the winter food limitation would appear to be simple but is fraught with problems. Everyone believes that food is an ultimate limiting factor, so that it must be involved in the cyclic dynamics. We began testing food limitation in the mid-1970s and found that one could add natural food or artificial food (rabbit chow) and apparently have no effect on cyclic dynamics. Hares came to the food grids so the density increased by immigration, but the decline started at the same time and at the same rate as on control grids. So what is the role of food?

Our next attempt was to do a factorial experiment adding food, reducing predation, and doing both together. The details are important, replication was never enough for the manipulated treatments, we did it only for 10 years rather than 20 or 30. What we found was that there was an interaction between food addition and mammal predator exclusion so that the combined treatment increased to a much higher density than any single treatment. But this result came with a puzzle. What is the role of food? Hares showed no evidence of malnutrition in the peak or decline, fed hares did not increase their reproductive output. What produced the strong interaction between food addition and predator reduction?

The next breakthrough came when Rudy Boonstra suggested that predator-caused stress might underlie these strange dynamics. Because we could now measure stress with faecal cortisol measures we could test for stress directly in free-ranging hares. The surprise was that this idea worked and Michael Sheriff capped off the stress hypothesis by showing that not only does predator-induced stress reduce reproductive rates, but the stress effect is inherited maternally in the next generation.

The bottom line: the whole dynamics of the snowshoe hare cycle are predator-induced. All the changes in mortality and reproduction are direct and indirect effects of predators chasing and eating hares. The experimental food/predator interaction was mechanistically wrong in targeting food as a major limiting factor.

This of course does not mean that food is irrelevant as an important factor to study in hare cycles. In particular very high peak populations damage shrubs and small trees and we do not yet have the details of how this works out in time. Secondary chemicals are certainly involved here.

Why does all this matter? Two points. First, the hare cycle is often trumpeted as an example of a tri-trophic interaction of food – hares – predators, when in fact it seems to be a simple predator-prey system, as Lotka suggested in 1925. Models of the hare cycle have proliferated over time, and there are far more models of the cycle in existence than there are long-term field studies or field experiments. It is possible to model the hare cycle as a predator-prey oscillation, as a food plant-hare oscillation, as a parasite-hare interaction, as a cosmic particle – hare oscillation, as an intrinsic social – maternal effects interaction, and I have probably missed some other combinations of delayed-density dependent factors that have been discussed. That one can produce a formal mathematical model of the hare cycle does not mean that the chosen factor is the correct one.

The other point I would leave you with is the large amount of field work needed to sort out the mechanisms driving the population dynamics of hares. Ecology is not simple. This enigma of the ten-year cycle has always been a classic example in ecology and perhaps it is now solved. Or perhaps not?

Boonstra, R., D. Hik, G. R. Singleton, and A. Tinnikov. 1998. The impact of predator-induced stress on the snowshoe hare cycle. Ecological Monographs 68:371-394.

Boutin, S., C. J. Krebs, R. Boonstra, M. R. T. Dale, S. J. Hannon, K. Martin, A. R. E. Sinclair, J. N. M. Smith, R. Turkington, M. Blower, A. Byrom, F. I. Doyle, C. Doyle, D. Hik, L. Hofer, A. Hubbs, T. Karels, D. L. Murray, V. Nams, M. O’Donoghue, C. Rohner, and S. Schweiger. 1995. Population changes of the vertebrate community during a snowshoe hare cycle in Canada’s boreal forest. Oikos 74:69-80.

Keith, L. B., and L. A. Windberg. 1978. A demographic analysis of the snowshoe hare cycle. Wildlife Monographs 58:1-70.

Keith, L. B. 1990. Dynamics of snowshoe hare populations. Current Mammalogy 4:119-195.

Krebs, C. J., S. Boutin, R. Boonstra, A. R. E. Sinclair, J. N. M. Smith, M. R. T. Dale, K. Martin, and R. Turkington. 1995. Impact of food and predation on the snowshoe hare cycle. Science 269:1112-1115.

Krebs, C. J., S. Boutin, and R. Boonstra, editors. 2001. Ecosystem Dynamics of the Boreal Forest: the Kluane Project. Oxford University Press, New York.

Sheriff, M. J., C. J. Krebs, and R. Boonstra. 2009. The sensitive hare: sublethal effects of predator stress on reproduction in snowshoe hares. Journal of Animal Ecology 78:1249-1258.

Yan, C., N. C. Stenseth, C. J. Krebs, and Z. Zhang. 2013. Linking climate change to population cycles of hares and lynx. Global Change Biology 19:3263-3271.

Does Forestry in British Columbia Make Money?

While driving around British Columbia, one cannot help but notice the forestry industry – bare clear-cuts on the hills, logging trucks on the road. This simple observation leads me to this question: is the forest industry that now exists in BC profitable when one does a full-scale life-cycle analysis of its environmental impacts?

The answer to this question is obvious to most people – forestry is a good renewable-resource industry that provides many jobs and promotes economic growth. There is much literature from the government and the forest industry about how BC utilizes sustainable forestry. Most people accept this positive view of the forest industry. But I am concerned that we might find a different answer if we look behind the smoke screen of advertising and the government’s rosy view that all resource extraction industries are valuable for BC. Why might this be? I cannot analyse the economics of the forestry industry because I am not an economist, so in some sense all I would like to do here is ask some questions that others who are more qualified might help to answer.

The first question is what to include in such an analysis. If forestry is considered only trees, rather than the whole ecosystem with all its biodiversity, you would get one answer. If you worry about biodiversity you might get another answer (e.g. Drever 2000). If you worry about climate change and carbon dioxide dynamics, you can view forests as carbon stores that might be valuable if there is a price on carbon in the future. If you value the forests of BC as ecosystems that ought to be left as a legacy to our grandchildren, you might again take a different perspective. Do you include in your balance sheet the costs of fire-fighting and the government departments that manage the industry? What external costs are left out of a broad overview of forestry in BC?

At present it would appear to me that forest harvesting is not sustainable in BC, even if you take the narrow view that only trees matter in the calculations. If it were a sustainable industry, there would be no need to harvest old growth forests. But you could be certain that if any government actually said ‘no more cutting of old growth’, there would be an outcry. But if we continue as we are, we will cut our way to the North Pole, as long as we can find trees. The Yukon is next, if not now then for our grandchildren. But trees grow back again, so all will be well. Restoration ecology to the rescue. If you take a biodiversity perspective, you might find that what grows back is a pale imitation of what was there before. And if the ecosystem does restore, the time frame may be very long, looping back to the question of what sustainability means. If the forest ecosystem restores itself in 300 years, is that sustainable? How about 500 years?

If we treat forestry like any other agricultural enterprise, we might allocate some fraction of land to this activity and use the rest for recreation, tourism, and truly sustainable activities like berry picking. Suppose we planned that by 2020 forest companies could not cut anymore on crown land, and by that date land would be allocated to companies to purchase like any farmer would buy a farm. I can hear the howls of protest to such a suggestion. Is it correct that forestry then is really a mining industry operating on non-renewable resources – crown land that has old growth that belongs in theory to the people of BC in perpetuity? There are reports of how some forest companies are short-changing the government in their cutting practices because of the failure of inspection of the amount of wood taken off an area (e.g. see Parfitt, 2007) Short-changing the government is short-changing the people of the province and the people of the future who would live here.

But it seems to me that a much larger issue is that much of the planning for forestry in BC ignores the biodiversity issue. To be sure an iconic bird or plant might have some small areas saved for it, if it is included on the threatened species list. But as any ecologist might suggest, these protected areas are postage stamps that are in the long-term insufficient for the conservation of the species of concern. The major conservation issues of our day are those where economic growth produced by harvesting trees, natural gas, oil or coal collides directly with protecting our ecosystems for future generations. By any measure, the economic agenda wins the day, and the biodiversity agenda is peppered with good advertising telling us that all will be well.

It is fortunate that the First Nations of BC are rapidly awakening to these issues, and progress has been made in giving them more authority over their traditional lands. This is a bright side of the global issue of conservation in Canada.

The political issue that flows from this discussion is to ask how much subsidy our BC government provides to aid the exploitation of our natural resources, resources that ought to be managed for the future of the people of BC. Are we subsidizing environmental destruction with our tax dollars and all the while being told that even more economic growth is necessary? There must be another way, and for an ecologist concerned with biodiversity and the protection of the natural resources of our province, the current policies look like a Ponzi scheme.

Drever, R. 2000. A Cut Above: Ecological principles for sustainable forestry on BC’s coast. David Suzuki Foundation, Vancouver, B.C. ISBN 1-55054-689-9, Available at

Parfitt, B. 2007. Over-cutting and Waste in B.C.’s Interior: A Call to Rethink B.C.’s Pine Beetle Logging Strategy. Canadian Centre for Policy Alternatives, Vancouver, BC. ISBN: 978-0-88627-533-4, available at f