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On the Trails: Autumn is here in earnest

Posted: October 4, 2013 - 7:13am
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Swamp gentian seeds nestle in splash cups formed by the seed capsule until a rain drop pops them out.  Photo by Kerry Howard
Photo by Kerry Howard
Swamp gentian seeds nestle in splash cups formed by the seed capsule until a rain drop pops them out.

We pass the autumn equinox, and the days get ever shorter. They’ve been getting shorter ever since late June, but now we really begin to feel it. The fall rains are here, and when we look out our windows, we see gray gray gray. It’s seldom as bad as it might look, however, so it pays to get out and about.

In fact, I think that getting outdoors is an important part of living with short days and gray skies. Some folks flee the fall and winter by going south, but I have found several ways to enjoy staying here during those seasons. I try to get outdoors every day, talking a walk on one of our trails; maybe not a long walk, but I’m out in the fresh air, seeing something besides four walls. I sometimes play a game with myself: the challenge is to find at least one thing (preferably three things!) of esthetic or natural-history interest. Sometimes these things are connected: I like to recall the visiting musician who took a walk in the forest and found that the rich variety of green tones in the mosses and ferns reminded him of a piece he had just played; now every time he plays that piece, he’ll see the rainforest. I greatly enjoy the rich cultural life in town, especially the music; the visual and thespian arts are also alive and well, and various lecture series can be both instructive and entertaining. Also, I do best when I have a project or two to work on; it doesn’t much matter if it is writing or building bird houses — a project that engages what’s left of my aging mind.

When I’m out, there are actually several autumn things to look forward to. Great rafts of scoters gather in the coves and channels. It is fun to watch them do what I call ‘chain diving’— a whole line of scoters dives, one after the other, in the same spot; then they all come up, one at a time, a little farther away. I have not yet found anyone who can tell me exactly what they are doing or what food they might be finding or why they do it in that way.

Out on sandy, gravelly bars, there might be small flocks of shorebirds that spend the winter with us. Rock sandpipers and dunlins often hang out together. Adults in breeding plumage of both species have black belly patches, and some show the black blotches as winter goes on, so look closely to distinguish them. These shorebirds breed on the Arctic tundra of western and northern Alaska. Sometimes there are surfbirds on rocky reefs and points; they nest in alpine tundra of Alaska and the Yukon. I occasionally flush a solitary snipe, not only in the marshes and swamps where they might have nested but even along streams in the forest.

I look forward to spotting the first slate-colored juncos that arrive at the bird feeders; they come from the Interior to spend the winter with us. Oregon juncos live here all year but mix with the slatey ones in winter. At present, both kinds of juncos are classified as the same species but different subspecies or races.

Thinking about Oregon juncos reminds me to ask a question: these birds are distinguished from slate-colored juncos in part by a chestnut-brown back. Likewise, our chickadees have chestnut-backs that are lacking in the other North American chickadees. Is there a particular reason why chestnut backs are popular here? Is there something about rain forests that favors that plumage pigmentation?

Of course, the black-billed magpies come to us in the fall too. They temporarily monopolize bird feeders, tease the eagles, and sample leftover salmon carcasses. On a rare sunny day, the iridescence of their black feathers makes them quite spectacular.

Flowering season is over in fall, but you might spot a few late purple asters alongside the trail. Behind the Visitor Center at the glacier, there has been a very late blooming Romanzoffia sitchensis (the common name is Sitka mist-maiden). In the muskegs, look for tiny yellowish cups that might be mistaken for flowers. These are the seed heads of the swamp gentian. Each two-parted cup holds a little cluster of seeds; when a rain drop hits the cup, the seeds get splashed out and so dispersed. This ‘splash-cup’ dispersal is not common, but it is shared by the bird’s nest fungus.

One of my favorite things to do is watch the coho arrive in local creeks. When they do, the bears — which have been waiting for them, ever since the sockeye run ended — get busy again in the streams, and that makes for great bear-watching. I think that many of our local bears really depend on coho to “top-up their fat deposits in preparation for hibernation. The amount of fat laid down in fall is important in determining how many cubs a female bear can feed while they are in the winter den and it is probably important for winter survival of juvenile, subordinate bears that are not yet expert foragers.

I don’t know all the factors that regulate the size of coho runs, but there is evidence that juvenile rearing habitat is one important factor that helps determine the size of a local coho population. Incoming adult salmon are commonly able to slither over or jump over most beaver dams, so dams seldom limit the spawners. However, juvenile coho rear in pools in streams and in beaver ponds, and research has shown that they grow really well in beaver ponds. Down in the Pacific Northwest, biologists have even re-introduced beavers to certain stream systems, so that their ponds will increase the available rearing habitat for salmon and help restore the diminished populations. Because salmon typically return to their natal stream when it is time to spawn, juvenile rearing success helps determine the size of the spawning run. Thus, when beaver dams are removed from streams where coho spawn (so that their ponds are drained), or when beavers are trapped out of a system and their dams (and ponds) are no longer maintained, and rearing habitat is thus reduced, there is reason to expect that the coho population of that stream will decrease. And that leads to the expectation that the bears living in the area would lay down less fat, possibly survive less well, and produce smaller litters of cubs.

• Mary F. Willson is a retired professor of ecology.

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