Assisted Migrations


In my mind, every month has a color. January is white, fresh and new and snowy. February is kind of a twist cone of vanilla and brown. March is blue, as the sudden return of daylight on my drive home gives the sky's color prominent positioning in my brain.


April is the color of dutchman’s breeches, a soft eggy color shared with a few other of its ephemeral counterparts. May is bright green, turning rainbow in June as the blooming season kicks into full gear. July is the color of light sand as hot dry weather mutes the emerald growth of early summer.


August has candy paint, shimmering in different hues as it passes by. From head on it appears jungle green, turning yellow with the fluttering of early leaf drop from walnuts and cottonwoods. Winding into the past it turns burgundy, the color of prairie grasses sending up seed heads in the waning daylight.

Big bluestem in flower

In that way August represents a transitional phase. Every month afterwards gradually slides down the color spectrum, from yellow September to orange October and a rusty-red November preceding the inky darkness of the winter solstice.


But August finds itself tugged by both ends of the phenological cycle. Walking in the woods we might still see the leaves of bloodroot, and hear the songs of warblers. At the same time, mast-producing trees start casting off their crop, picking and choosing which acorns or walnuts or hickory nuts to hold on to until fully ripe. The bird songs die down with the end of nesting season and the first elements of fall migration make their appearance.


Our native plants going to seed represent one such migration, even though we don’t often think of it this way. The fluffy seeds of little bluestem open their fibrous wings, ready to take flight on the wind to find their way to a suitable location. Larger seeds, like sunflowers or acorns, hope to either roll their way to a new locale or catch a ride from a squirrel or bird caching winter food supplies who (hopefully) forgets to eat it later.



Ecologists have a variety of words to describe how seeds get around. "Zoochory" when animals move it. "Anemochory" when wind moves it. "Myrmecochory" when ants, specifically, drag seeds around. But when humans do it, we call it assisted migration, and it can take a few different forms.


Assisted migration has garnered a lot of interest, and concern, since the term first appeared in 2007. Most of the conversation has centered around using assisted migration to mitigate the biodiversity fallout of climate change, building on a process that's already underway. Some species can and have shifted their range as previously-inhospitable habitats become climatically favorable for their colonization.



But those that can’t keep up with the rate of change will face extinction. Turtles move slowly. Trees don’t move at all. That’s one reason the Iowa DNR and the USDA germplasm lab have mobilized an effort to preserve Iowa’s native white pine genotypes; in a future where warmer, rainier conditions in Northern Minnesota threaten its pine-based timber industry, perhaps Iowa’s white pines can be brought in with their ready-made suite of adaptations for milder climes to keep things afloat.


Other applications of assisted migration relate not to the climate, but to fragmentation. I know this is Iowa but sometimes, even if you build it, they don't come. Bison would never have magically wandered in to the Neal Smith National Wildlife Refuge, no matter how suitable the habitat. Historically present species like the prairie chicken had no way to get from their last holdouts to the west back into Iowa without our help.


Prairie Chicken

The ancient prairie had no need for assisted migration. Seeds could blow freely across the landscape with a reasonable chance of landing somewhere acceptable. Within species, cross-pollination could occur between populations adapted to dry upland soils and those from the soggier valley below, making more resilient offspring who can handle whatever the future holds. Prairie chicken populations could expand and contract as dictated by the shifting sands of food availability and predation.

Finding wildflowers in suburbia

Today, those seeds find few suitable landing spots once they leave their tiny preserve. And it’s not likely a pollinator will bring in different genetics; rarer plants might not have a counterpart in existence for miles. Prairie chickens need 25-30,000 acres to thrive. Isolated prairie plantings, and highly fragmented remnant landscapes offer little opportunity for flora and fauna to actually expand their range - at least not without our help.

Prairie strips, oases in the desert for prairie species who can tolerate small scales

Which brings me back to the color of August. The waving seed heads of prairie grasses remind me it’s time to start thinking about assisting in their migrations. There’s some prairie cordgrass I need to dig up for shoring up the fish habitat project at Bloody Run. Some leadplant at Motor Mill is positioned to drop its seed over a cliff into the too-shady forest below; I should probably collect that and at least scatter it in a bare sunny spot further back from the edge.

There’s a nice patch of cardinal flower down at Frenchtown; I wonder if we could get this plant back in the mix along the Osborne Pond?

Cardinal flower at Frenchtown

An young bur oak along near the wildlife exhibit looks like it’ll have a good year for acorns. I wonder if I can collect a few and strategically place them somewhere the mower won't shred them.

Bur oak near the wildlife exhibit

Assisted migration definitely has its critics. Rightly so. The history of humans attempting to move plants or animals to new locales is an ugly one. In 1890, a theater group in New York wanted Central Park to have “all the birds Shakespeare ever mentioned,” and 130 years later I’m hazing European starlings from my patio feeder all winter so the native Iowan birds can get a bite.

I got your slings and arrows right here

Multiflora rose, thought in the 1930’s to be a great solution for livestock containment and erosion control thanks to its high viability and rapid colonization, has turned out to be even worse for our prairies than unconstrained grazing.

Conservationist Louis Bromfield admiring his carefully-constructed hedge of invasive plants

Cane toads introduced to control pest insects in Australia quickly multiplied out of control. Wolf snails in Hawaii, introduced to eat a different invasive snail, didn’t stop at the targeted prey and now wreak havoc on the islands’ native mollusks. The list goes on, worldwide, of where assisted migration proved to be a spectacularly bad idea.


But for the prairies here in Iowa, there’s no other choice. Often, all four cardinal directions out of a remnant prairie are essentially dead ends. We have to be the ferry across rivers of asphalt, corn, and beans if we want rare and sensitive species to persist, let alone expand their range.


That’s why this fall we’re hoping to get some assistance for our assistance. We can’t pick prairie seeds with a mechanical harvester, so what we need is some good old fashioned elbow grease. We’ll be hosting four public prairie harvest days between September and October to collect some seed. If you’re not a plant ID expert don’t worry, neither are we, but we know enough to get you started.


We always need seed on hand to revegetate after construction projects, flood damage, etc. This winter we're also hoping to do some experimentation with starting prairie plugs which will eventually go into bolstering existing streambank stabilization projects at Bloody Run, Big Spring, Joy Springs, and Osborne.


Deep-rooted prairie plants will help improve the longevity of these projects, but there's one other big advantage - connectivity. Our riparian corridors represent an opportunity to establish quality habitat along high-traffic zones for wildlife.


Putting native plants in those settings means a shorter flight for pollinators, and a better chance for one plant's pollen to find a partner. It means better stopover sites for migrators using the rivers to navigate their way north and south. Even the river itself can provide a sort of "assisted migration" once the plants establish along its banks. Indeed, hydrochory is a major strategy for a lot of our most invasive plants like Japanese knotweed, but if you’ve ever paddled through a backwater slough loaded with silver maple samaras you know it’s not just the bad guys getting around this way.

I think of seed collecting and translocating like pushing a kid on a swing. You might have to push a few times before they figure out how to use the swing, but once they do, they’ll keep swinging all by themselves. That’s what we’re hoping for with assisted migration; just a little push to get them ride started.


Looking Back

Another August come and gone, another crop of seasonal help out the door and on to the next instar of their metamorphosis from students to professionals! Many thanks to this year's seasonal staff Anna LoFaro, Buck Wachendorf, Jake Frederick, and Natalie & Emily Palmershein!


The seasonal naturalists got in a few last programs before going back to college life. The Mississippi River Adventure Day on August 1st saw kids from all over the area spend a whole day exploring and playing with the river from adventure basecamp on St. Feriole Island.


On August 9th, they headed to a different river with a different group of kids for STEAM camp, a day centered on science, technology, engineering, art, and mathemetics using the Motor Mill Historic Site to anchor their experiments.


On August 18th, the O.W.L.S. headed north to the beautiful Porter House in Decorah, which... yes I'm just getting word now that it is an actual house and not a delicious steak. Still sounded like a good time.


Last but not least a big project got underway at the Becker West Wildlife Area, where we'll be repairing a small retention pond this fall and clearing an old treeline to promote grassland bird habitat and reduce the fragmentation of that particular prairie.


Looking Forward September is looking super busy here at Osborne!

Nature Kids on Sept. 10th will rock. Kids will learn a little about geology before heading down to the Volga River to look for fossils, artifacts, and whatever other treasures the river brings for that particular day.


O.W.L.S. will take a trip back to the Days of Yore on September 15th with a visit to the state mental health institute in Independence. The facility houses a museum with relics from throughout its long and storied history.

On September 17th, naturalist Abbey will host a night hike at the Motor Mill Historic Site! This will be a great family-friendly opportunity to see and hear the night shift in the woods and prairies surrounding the old town site.

On September 22nd we'll host our first "Pickin' On The Prairies" volunteer seed harvest day at the Osborne Pond, so if any of the above article tripped your trigger on assisting with some migrations, come on out and get your hands dirty. You'll have another chance on September 29th at the Motor Mill Historic Site.

Attracting Success, a summit on September 23rd, promises to be a can't-miss for entrepreneurs and young professionals. For more information and to register, click here.

For more information on any of these events, check out the "events" tab on this website or call us at 563-245-1516!

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