Field Notes—

Strange Days In The Umwelt

By Curtiss Clark

Our dog, Boon, a scent-hound mutt with the doleful aspect of an undertaker, has been about as upbeat and cheerful as he gets over the past couple of weeks. The earth has opened up its trove of organic smells, and the Boondog has been reading the property like a newspaper, over and over, reliving the exquisite tragedy surrounding the bird carcass in the hedge, the subtle yet sublime gustatory nuance of owl pellets beneath the spruce tree, and the deep, moving mystery of voles stirring in their subterranean realms.

In watching him on his administrative rounds of the yard, his snout to the ground, scouring the landscape for the very latest scent, I can see that, while I am gainfully employed as a journalist, he is the one with the true nose for news. Humans have about five million olfactory receptor cells; scent hounds, up to 200 million.

Spring is a time for the senses, no matter what your species or occupation, yet our experience of the world in spring, or any other season of the year, is quite species-specific.

Just over 100 years ago, the German biologist Jacob von Uexküll noted that different animals living in the same ecosystem often depend on different environmental signals for their survival. The specialized subset of sensations that are critical to a given species’ existence defines the world for them. Uexküll described this sometimes narrow slice of experience as the umwelt, which translates loosely as the surrounding world.

Now that spring has warmed and encouraged new growth in our surrounding world, Kate and I have spent a fair amount of time outside poking at the gardens and flower beds in a reverie of anticipation. We always enjoy this time outside in the company of our dog, and we assume that he is sharing our objective reality — our umwelt. It never occurs to us that there is a reality beyond what we can sense — a reality that Boon, with his olfactory superpowers, experiences every day. How strange and bizarre our lives would be if we had to negotiate our way in the world by nose, parsing experience molecule by pungent molecule, as he does.

The more one explores the uncounted possibilities for life in the natural world, the more exclusive and limited our human experience appears. How many thousands of strange and confounding realities are there just beyond the boundaries of our own peculiar umwelt?

Consider the juncos flocking and feeding on the sunflower seeds we have set out in the birch tree. It is mid-April and these birds are still far south of their nesting range. Any day now, they will migrate north. Researchers believe that migrating birds — along with honey bees, sea turtles, salmon, and other species with keen navigation skills — can actually sense the earth’s magnetic field, which is created by the flow of the planet’s molten core and a concurrent flow of ions in the atmosphere. Magnetite has been found in the nervous systems of these species; the tiny magnetic crystals line up in the presence of magnetic fields. Imagine a reality in which your nervous system is attuned simultaneously to the earth’s core and its atmosphere, and it is sending you signals to move in a certain direction.

What about creatures that are relatively senseless? Take the lowly and ubiquitous tick, which is widely despised as a creepy agent of disease in our particular umwelt. Ticks are deaf and blind, and yet they proliferate on these fine spring days, finding their way by touch to the tips of leaves and grasses where they wait for a meal. Of all the sweet smells of spring, the tick yearns most for the odor of butyric acid, which wafts from the sebaceous follicles of all mammals. Just the slightest whiff is enough to inspire a tick to launch itself into oblivion with the hope of landing in a hairy tangle, which after some struggle leads to a barrier of cutaneous tissue (skin), through which the poor creature must plunge its head to suckle in a pulsing stream of warm blood. Ah, spring!

Perhaps our human senses limit us, but they also spare us some very strange days. Still, we can take consolation in the mutability of sensate reality when things don’t go our way. As those April showers work overtime on May flowers, why walk around in the rain with the doleful look of an undertaker… or a dog? It’s still a good day for ducks.

(More than 75 other essays in Curtiss Clark’s Field Notes series can be found at www.field-notebook.com )