On House Mouse Outbreaks in Australia

It occurred to me after some recent discussions that the problem of house mouse outbreaks in Australia is almost a paradigm for modern ecological science. A brief synopsis. At irregular intervals house mice (an introduced pest) reach high densities in the wheat growing areas of eastern and southern Australia, and cause serious damage to wheat, barley, oats, and sunflower crops. There are two approaches to this applied problem.

The ecological approach is to understand why these outbreaks occur and why for many years (2-9 years) between outbreaks, hardly a mouse can be found. This approach has been highly successful led by a series of excellent Australian ecologists over the last 40 years. The key limitation is food, combined with social interactions, and the food supply is driven by rain at critical times of the year to provide seeds for the mice. There are no competitors for house mice, and there are a few insignificant predators, overwhelmed by the mouse’s high reproductive rate. These ecological facts are clearly known, and the job now is to build the best predictive models to help the farmers anticipate when the outbreak is coming. There are still important ecological questions to be studied, to be sure, but the broad outline of the ecological play is well described.

The management approach is much simpler because farmers can control house mice with poison, primarily zinc phosphide, and for them the question is when to poison, and secondarily (over time and with more research) can we develop better poisons so there are few non-target problems. Poisoning costs time and money so good farmers wish to minimize these costs.

The long-term issues get lost in this situation, a model of the way the world operates now with ecological and environmental problems. Questions about sustainability multiply in any system dependent on poisons for a solution. Will the target organisms become resistant so the poison does not work? Many examples exist of this already. Are there any long-term problems with soil organisms, or non-target species? No research yet on these issues, and perhaps they are more serious with herbicide applications in agriculture. And while predators do not control house mice during outbreaks, they do eat many of them and this food pulse may have implications for the wider ecosystem. We focus on farming and forget the wider ecosystem which has no dollars attached to it.

Ecologists recognize that these issues are not the farmers’ fault, but we raise the question of who worries about the long-term future of this system, and the answers to these long-term questions. The government is rushing to get out of long-term ecological and agricultural research and we leave problems that do not have immediacy.

Consequently we become short-sighted as a society. Long-term research becomes 1-3 years and not the 50-100 years that ecologists would support. And consequently applied ecologists bounce from one problem to the next under the paradigm that, no matter what we do, science will come up with a technological fix. There should be a better way. To go back to our house mice, we might ask (for example) if we implement no-till agriculture, what will be the consequences for house mouse survival and future outbreaks? The practical minister of agriculture will respond that we have no time or money for such research, so we lurch along, managing the world in an ad-hoc manner. There should be a better way. But meanwhile we must follow the money.

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