Backing into Eden Chapter 11: Invasion and Migration

Almost every summer weekend, there are programs in the local parks where volunteers gather to remove invasive blackberries and plant native plants.  It’s a tough fight – the invasive berries are tall and thick-caned and full of stickers.  Volunteers sometime emerge with torn long-sleeved shorts and red rivulets of blood on their arms.  At least they are slaughtering plants.  Right now, officials are deciding whether or not to hunt down over 3,500 barred owls, an invasive predator that is driving spotted owls away from a limited habitat.  This isn’t the first time I’ve referenced this problem in this series, but I find this decision to be terrible and iconic.  I love owls, and I cannot image either killing thousands of them – most likely with shotguns from the articles I’ve read.  Nor can I imagine stepping back and allowing the spotted owl to die off.   We often hear owls in the trees outside of urban backyard.  Sometimes we  stop our own chatter and listen to them talk back and forth to each other.

A Barred Owl - from istockphoto  - copyrightedThere are many more stories about migrations colliding or changing as the climate changes.  For example, it turns out that sea life migrates up at night to feed near the surface and down during the day to hide.  Even these “horizontal migrations” are affected by climate change, which is expected to lower oxygen levels in the ocean.  This may force sea creatures  to change the depth at which they hide during the day, trading a safer home for a more dangerous one where it is easier for predators to feed.

In her Kindle Single book, “Battle at the End of Eden,” Amanda R. Martinez discusses the killing of multiple invasive species on islands.  The invaders – often rats (but not always) – were killing seabird populations with limited habitats. They ate eggs and babies, and sometimes even adult birds.  Islands are a unique ecosystem for this problem – because they are smaller, it’s easier to see what is happening.  And perhaps also easier to make a difference.  If a species needs to be eradicated (yes, eradicated – or for another word, think genocide), then success or failure is easier to track on an island.

I talked about this problem in chapter eight.  I was planning to go on and talk about genetically changed life, but I clearly haven’t finished thinking about killing to save lives. If I said, “Let’s kill off the purple people and keep the blue ones,” it would sound like thinly veiled racism.  But now have a federal plan to kill barred owls to save spotted ones.  It doesn’t feel right.  Very little about this series is comfortable; I don’t want the natural world to need us.  I know we need it, but it feels like nature should be stronger and more enduring than us.

Animals compete.  This is what evolution is about. As climate change intensifies, animals are going to be moving further into each other’s territory and native animals are likely to lose.  Birds that we love (barred owls) are going to threaten other birds that we love (spotted owls).

Speaking of birds, I’ve gained new respect for the Audubon society. I’m not a member.  I don’t carry binoculars and bird books with me, or get tweets from my citizen-science  friends when a rare species flies through in my neighborhood.  I notice the Canada geese and the robins, but they are noisy and plentiful.  I can often spot an eagle, but they are also plentiful here in the Pacific Northwest, in this moment.  Thank you, Endangered Species Act.

Even though I’m no birder, I recently listened to a GIS researcher talk about the work being done to set conservation goals for the Audubon Society.  She mentioned that almost all species of birds are expected to change habitat due to climate change.  Then she described three buckets that the Society is sifting birds into.  I’m paraphrasing, but it goes something like this:

  • Bucket:  Birds that have a large habitat and are reasonably adaptable.  These birds may find that their habitat shrinks on one edge and grows on another, and will probably manage through the changes.  The barred owl may be one of these – they have migrated all the way over here from the east coast, and part of the reason they are out-competing the spotted owl is that they have a much more varied diet.
  • Bucket 2:  Birds that have a small to medium sized habitat (or perhaps a narrow migration corridor and time window) and which will still have habitat left for them.  These birds will struggle some, but reasonable mitigation and/or direct assistance is likely to save them.
  • Bucket 3:  Birds that have a small habitat, and will have a small habitat, distant habitat, or no habitat left after climate change.  Or perhaps, like the spotted owl, habitat where they can’t compete well.  Larger conservation efforts might not have any success.  The spotted owl may be one of these – difficult to save at this point. I’m not sure how the Audubon classified them, but they aren’t on the priority bird list of birds the Audubon is spending resources on.

After this classification, the Audubon Society is putting its resources into the middle group of birds.  Here is what the society says in its most recent strategic plan:  “Audubon’s priority bird species are birds of significant conservation need, for which our actions, over time, can lead to measurable improvements in status.  Eighteen are Red WatchList species, 23 are Yellow WatchList species, and 8 are Vulnerable Common Birds. The breadth of this list reflects the dramatic loss of habitat and the pervasive threats that confront birds and wildlife.”

Most importantly, this strategy means that resources are being put where they can do the most good.  This should be done for other groups of plants and animals as well.  Then, the choices about varying parts of the ecosystems (avian mammal, plant, other) can be over-layed on maps which might allow conservation groups to work together (using big data) to make the smartest possible investments in animal conservation.

I sometimes imagine that if we put money and resources into saving the right species, we might not have to destroy others.  But even the Portland Audubon Society ultimately – and with great reluctance from what I can tell – chose to say that, “After careful consideration, it is Portland Audubon’s position that the highest priority must be placed on preventing the extinction of the northern spotted owl even to the degree that this entails lethal control of another protected species.”  The entire letter is linked below.

Me and a waterfall in the home of spotted and barred owls

Successes are very possible. Bird populations on some of the islands where invaders were eradicated are now thriving.  The Audubon society is likely to continue saving birds – they have a long history of conservation, deep pockets, and committed members.  I’m not sure what will happen to the spotted — or barred – owls up here. Chances are good that one species or the other will thrive in our forests.  It already looks like they can’t live there together.

I’ve heard that up to one in four mammals are expected to become instinct soon.  One in four.  It seems that  some intervention to mitigate the damage we’ve done may be in order, even though we may not like where that takes us.  Like the Portland Audubon society, we’re going to have to make some choices and we’re going to have to prioritize.

Oh, and I may go join the Audubon Society.  They are likely to be one of the main forces in the gardened world, the Eden we’re backing ourselves into.

Apologies for the time between posts – not only was I worrying about this kind of choice, but I also prepared and delivered a talk on this topic at the World Future Society meeting in Chicago in late July.  That took the time I might have given to writing new chapters.

As always, here are some of the links that lead to research I used for this chapter:

The Spotted Owl’s New Nemesis, Smithsonian magazine, January 2009, Craig Welch

Wildlife Officials Consider Killing Barred Owls to Save Spotted Owls, KQED Science, NPR, July 24, 2013, Mike Osborne

Climate Change and Migration,  Encyclopedia Brittanica, Advocacy for Animals, January 27th, 2013, Gregory McNamee.

Migrating animals add new depth to how the ocean “breathes” (Nature Geoscience), Princeton Journal Watch, Princeton University, June 24th, 2013, Morgan Kelly, Office of Communications

Audobon Strategic Plan 2012-2015

Portland Audubon letter to the US Fish and Wildlife Service


Sign Up

Scroll to Top