The Naturals

I love it when something you read or experience offers you insights that then cascade to other regions of your brain and trigger a “eureka” of understanding. I guess that’s how our brains work as we stair-step from one developmental stage to another. I recently read two books that each, in their own way, helped me better understand how complex ecosystems work. The first, Return of the Sea Otter by Todd McLeish, describes how the health of kelp forests along the Pacific Coast was due in large part to the actions of sea otters, who kept the sea urchins that eat kelp in check. The international fur trade once nearly wiped out sea otters. Apparently, their fur is about a million times more dense than the hair on human heads, even my daughter’s head on a humid day. Without the sea otters, the sea urchins were free to wreak havoc on the kelp, which in turn decimated the habitat that kelp forests created for numerous coastal sea creatures.

Sea otters are what wildlife biologists call a keystone species. Not to be confused with the residents of Pennsylvania, keystoners are like natural conservators. Without them, everything in their neck of the woods tends to go to hell. Google “keystone species” and you’ll be surprised by who’s on the list—prairie dogs, sea stars, termites, woodpeckers, hummingbirds, krill. It’s not just the big dudes, although jumbos like elephants are certainly represented. On the Great Plains, American Bison (aka. buffalo) were once keystoners. In OMG hard-to-fathom numbers, they once clipped and fertilized wide swaths of North America’s grasslands. They also wallowed their massive furry bulks in muddy depressions to cool themselves. Those wallows became ponds and ultimately wetland habitats.

In the Pacific Northwest, salmon are among the keystoners. Their epic current-defying spawning runs feed everyone from orcas and seals, to grizzly bears and wolves, to migratory bald eagles, to the towering cedars and redwoods that are ultimately fertilized by their rotting carcasses. Talk about a keystoner that keeps on giving. The same can be said for beavers in the Great Lakes and wolves in the mountain West. Beavers dam rivers, sorting sediment and regulating water flow for salmon and trout, and creating wetlands that nurture a rich diversity of plants, which in turn offer homes and food for countless birds, amphibians, reptiles, and rodents.

In the mountain West, it turns out that gray wolves labor like sea otters and once suffered a similar fate. They were hunted nearly to extinction because of their perceived threat to livestock. But in their absence, deer and elk multiplied and pigged out. Fewer saplings, shrubs, sedges, and wildflowers meant less habitat for small mammals, birds and even butterflies. Devoid of plant roots to hold stream banks, increased erosion filled in wetlands and choked streams. With their recent reintroduction at Yellowstone, much of this has reversed. Biologists weren’t surprised to see wolves rein in the elk population, but they didn’t expect them to change the land itself.

In Darwin Comes to Town, author Menno Schilthuizen, writes about ants as keystoners. Ants engineer their environment. Their highly organized societies build cities, grow crops, hunt and forage, and in so doing provide habitat for countless mites, flies, butterfly-caterpillars, woodlice, pseudoscorpions, millipedes, springtails and crickets. Collectively, these guys are called Myrmecophiles (literally, “ant-lovers). And, just as a side note, can I just say Myrmecophiles? Really? That’s what we’re going with? You couldn’t just say Ant Lovers, or Antus Loverus if you want it to sound more Latiny? It turns out that all those lovers of ants find ways to mimic the chemical signals that ants use to talk to one another, and thereby infiltrate their cities, where they feed on ant crops, ant pupae, ant dung and, well … ants! So in spraying a little Raid, you’re not just taking out a few ants but a whole colony of other tiny creatures.

Schilthuizen uses the story of the ants as an entree into describing humans as keystoners. We create cities that obviously destroy habitat for many, many plants and animals. But our cities also create new habitats which are then populated by those plants and animals that are best able to adapt to the many unique niches that urban architecture provides. Take deer, for example. In Athens you can’t swing a dead cat without … er … ok, so maybe I shouldn’t put it quite that way. How ‘bout songbirds! Yeah, let’s do songbirds. Cities tend to favor songbirds with higher pitched voices over those with lower pitched tones. Higher notes carry better in urban environments where human vehicles and machines tend to hum in those deeper registers. Since birds use their songs to communicate, those who can hear themselves and their kin do better. Schilthuizen offers a number of examples in a book that I highly recommend. Two of my favorites are about urban crows and catfish. Apparently, in some cities those smarty-pants crows have learned to use slow moving automobiles as giant nut crackers. They’ve taken to bringing especially hard acorns to urban intersections where, after waiting for the light to change, they place the shells in the path of soon to be moving cars. Once the cars go by, voilà—your nut monsieur! Similarly, catfish swimming in rivers that snake through urban areas have learned that pigeons, common city dwellers, also frequent urban waterways to bathe and drink and, well, pigeons aren’t bad tasting. In fact, they go down pretty easy with a little river water.

Such stories about urban ecology offer a timely reminder that humans are very much a part of the natural world. In the museum business, for years we have tended to segregate human history stories in one wing and natural history stories in another. Now, more and more we’re forced to face the stark reality that we’re all naturals. Separating the two removes an essential player from the mix. Humans have obviously had a tremendous impact on ecosystems around the world. Even in the polar regions, where very few humans actually live, our activities are today reshaping those landscapes. And on the flip side, the non-human life forms that inhabit this planet have obviously shaped where, when and how human societies thrive. Look at Idaho, a state who’s shape really doesn’t make any sense next to all those Great Plains rectangles. Three major ecological regions exist within its arbitrary boundaries—the high desert sage steppe South; the rocky, mountainous middle; and the green, lush forested North. Even though the state’s residents all call themselves Idahoans, the people that dwell in each region live very different lives, nudged in this direction or that by their plant and animal neighbors. And why not? People and the land shape each other. Any bonafide keystoner could tell you that.