Northwest Natural History By Rob Sandelin

This week in the Woods: Mid November 2004

The maple leaves have mostly all drifted through the autumn skies to find their resting place on lawns, roads and forest floor. Now is the time for the brief glory of the cottonwood, whose bright yellow flames show brightly for a week or so. Their tall straight trunks and upturned branches are easy to spot with their golden crowns of fall. The humble alder is usually one of the last to let go of its leaves, like a kid trying to stay up past its bedtime. In a few more weeks all the branches will be bare and the trees will be in their winter slumber.

The leaves that fall are the trees gift to the soil, each leaf still contains sugars that attract a host of decomposers which then liberate the other nutrients inside the leaf. There is a whole world in the first couple inches of soil and fallen leaves provide a huge energy source for literally millions of critters large and small.

When leaves fall into water they decompose and release a couple of molecules of organic fatty acids. These molecules have a charge like a magnet. One end of this molecule attracts other fatty acid molecules, the other end repels water, so these acids float on top the surface tension of the water forming a microscopic film. As they collect they also attract other materials. When water moves, such as in a stream, these fatty molecules get agitated and as the surface tension of the water breaks, the molecules coagulate and collect air, which creates the greasy yellow-brown foam you see on streams. People sometimes see this foam and think it's from pollution. Foam caused by pollution is white in color and not greasy and usually smells of soap. Natural foam is often yellow brown, a bit greasy and smells kind of fishy or organic, and definitely not soapy. I have heard this foam makes a great laxative but have never tried it myself.

Chipmunks are moving indoors these days, curling up snug in their food cached filled nests to snooze away the bad weather. Unlike true hibernators, which store energy in fat reserves, our littlest squirrel has stashed food and regularly uncurls through the winter to snack and even wander forth on occasion for a drink of water. Its bigger cousin, the Douglas squirrel is out and about all year long. This fall was an off year in our woods for Douglas fir cones, which is a primary food resource for the Douglas squirrel. This animal is territorial, and it uses its chipping voice to declare ownership of certain resources. This fall there was a considerable increase in squirrel boundary setting. I watched one large squirrel for several hours and he drove off another squirrel 6 different times, each time chasing the intruder to a particular point, then stopping and yelling at the interloper who dared him back with equal invective from about 20 feet away. The space between them I imagined as a squirrelly demilitarized zone, over which each faction watched the other but did not actually defend or control. To no surprise, this zone contained no tree or food resources.

On another day I watched a industrious Doug squirrel methodically collecting maple seeds. Each seed was examined and some were rejected. I looked over the rejects but whatever fault they had was beyond my ape brain comprehension. Typically these seeds are cached in a shallow hole, the seeds are separated from the "wings" and the wings are used to line the hole and also to cover it.

The overwhelming abundance of mushrooms of this fall have mostly turned to mush, leaving behind a few of the tougher varieties such as the coral mushrooms. Mushrooms are often decayed rapidly by other fungi, while others are eaten. Our native Bannana slug in particular enjoys many kinds of mushrooms. Often mice and of course squirrels also snack on fungi. I have found mushrooms where the edge of the cap was entirely nibbled all the way around, but none of the rest of the mushroom was eaten.

There are still fresh fruitings to be found but the explosion of September and October has muted to a trickle, and it takes considerable search to find a fresh specimen. One that might catch your eye is a small golden-brown capped mushroom with a ragged edge to the cap. This is the questionable Stropharia, which in our woods fruits just about anytime of year. What is questionable about it I have no idea, it seems like a fine upstanding mushroom to me. Perhaps it is questionable whether or not it is worth eating, which in my opinion is a poor excuse for such a name, since like all its fungi kin, it plays one or more critical roles in the workings of our forests.

The birds here now are the hardy, rain resistant residents such as the stocky Towhee which controls the ground, using their wings and tail flashes to move the Song Sparrows and Juncos off the prime feeding spots. In a few weeks these will be usurped by the Varied Thrushes, who move down from their mountain forests to spend the winter in the lowlands. Varied Thrushes are about the size of Robins, but they have distinctive stripes on the head and chest.

Meanwhile the black-capped chickadees roam the woods in packs, seeking out insect eggs and other tidbits from all angles of the branches. Often these bands are made up of several kinds of birds which spread out as they travel in search of food. The large noisily chattering flocks you see wheeling through the trees are most likely Pine Siskins, a small finch who wears a pinstripe suit. These birds often show up ill and weak at feeders and throughout the winter a few will die. This is the normal course of nature, and late fall and winter are the pruning season to remove the weak.

Varied Thrush photo courtesy of Tom Munson

If you are out and about and hear a ruckus of Crows and Jays it is a signal that they have discovered some sort of bird of prey and are trying to move it away. If you follow their calls you might be rewarded with a glimpse of an owl or a hawk. A week ago I did just that and got a nice look at a huge great horned owl, who was huddled close to the trunk of a cedar tree, and blending in so well that I stood right underneath and did not see it. The odd Who, who Whoocooksfor you call of the Barred Owl has been heard lately, and so has the rhythmic toot toot toot of the pygmy owl. Barred owls are a relative new comer to our woods, and they are increasing in numbers so obviously our forests are to their liking. They are perhaps the most complacent owl, and so they sometimes perch low and seem undisturbed as excited birdwatchers and children enjoy their presence. With all this owl activity the squirrels are no doubt a bit jumpy, since they are one of the primary lunch features on the menu of the larger owls.

From a mole tunnel near our bird feeder, a tiny Creeping Vole has been venturing out to snatch fallen seeds. He pops his little head out of the hole like a periscope, scans to ensure the coast is clear, then scampers into the open as fast as his little feet will go. Some of the time, he immediately reverses course and dashes back in to the safety of cover without even looking for a seed, disturbed perhaps by some shadow or leaf movement. Other times he frantically searches for a morsel, constantly glancing up and about and over his shoulder. Clearly this creature understands his place in the food chain. The fat gray squirrel on the other hand seems oblivious to any such fear, daintily hopping about as if he were the king of the world. This one will make a nice feast at an owls thanksgiving.

Let me know what you find out there. May our thanksgivings include giving thanks to nature, the source of everything we need.