Photo: Jay Mather.

Assisted Migration: A Debate Worth Having

Sep 25, 2020 by Jen Zalewski
What is assisted migration and what does it have to do with climate change? Stewardship manager Jen Zalewski takes a look.

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Climate change is something many of us think about every day. It’s happening now and hopefully efforts to reverse the trend will continue to gain traction in the months and years to come. But regardless, we are experiencing (and will continue to experience) the effects of this unprecedented challenge. Along with our attempts to mitigate and slow down the effects of climate change, we will have to respond to the changes that will inevitably affect our communities and our natural environments and resources. We will have to be creative and think outside the box.

There are many approaches to responding to climate change. Do we push back against change or accept it and learn how to live with the consequences? For example: as sea levels rise and tropical storms and hurricanes become more frequent and destructive, do we dike and dam and build and fortify our built environment or do we retreat from the inundation, slowly migrate inland, and rebuild in safer places? What about our natural environment? In some ways I suppose we have the same choices. Intensive management practices could help maintain habitat and help keep some vulnerable species in their current ranges. But this approach will likely be costly and may not even be successful. Or we can let things take their course and accept the inevitable—temperature and precipitation patterns will change, vulnerable plant and animal species will be extirpated in part or all of their range, other species will benefit from the change and increase in number, and still others rarely found there before will migrate into the transformed area.

Peck's penstemon, a flower that's endemic to Central Oregon. Photo: John Williams.
Peck's penstemon, a flower that's endemic to Central Oregon. Photo: John Williams.
Movement is the key to climate change—temperature, winds, ocean currents, people, wildlife—all moving and migrating in response to change. We don’t necessarily think of say, a tree, as a migratory entity. You’ve probably noticed that they do not have legs to run or wings to flee from a changing climate. But the range of a tree species does move. If conditions within the range of a species become less than favorable, while conditions on the edge of the range become more favorable, the range will slowly shift and the species, over many generations, may find itself in a new home. Unfortunately, the habitat changes associated with climate change are likely to happen much faster than a lot of species can respond to or migrate away from. So, should we help them??

Assisted migration (also known as assisted colonization or managed relocation) is the human-assisted relocation of species that are unable to move or adapt fast enough in response to climate change. It is a relatively new concept and a potential tool to possibly prevent the extinction of species.

A Western toad. Photo: Land Trust.
A Western toad. Photo: Land Trust.
Assisted migration has the potential to save a species from extinction. The human desire to stop extinctions is motivating. Most extinctions and impending extinctions are due to mismanagement of our natural resources. The vanishing of a species, never to return again, is often a clear and precise sign of our failure. But how much intervention is too much? By moving species around, might we do more harm than good? Maybe. One of the more frustrating aspects of climate change is that we don’t necessarily know HOW the climate will change. In some places this is clearer, but here in Central Oregon, the predicted changes to our precipitation patterns, one of the defining characteristics of our sensitive high desert climate, is unknown. So, we may know that a species’ current habitat is likely to become inhospitable in the near future, but we may not know where to move them so that they have a better chance at success in the future. Moving a species to a new habitat could also create competition with a species already present in the new habitat, trading one species problem for another.

Assisted migration is generally in the research stages in North America. In some cases, this management tool is already being considered to save species from extinction. Click here to read about how the Bay checkerspot butterfly may (or may not) benefit from assisted migration and the pros and cons of the practice as a whole. The plight of coast redwoods, sequoias, and other trees with slow migrating ranges and the potential for assisted migration to help these species is discussed here. Ultimately, it would be great if humans were able to come together and work towards a climate solution that did not involve having to make hard choices about these interventions. But in the meantime, keep your eye out for future debate regarding this practice and other creative solutions to preserve our planet’s diversity.


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