The presence of aspen probably means that a fire once swept across this dry western shoulder. Quick to invade new territory after a fire, aspens play an important role as a pioneer species of the western and northern American coniferous forests. Like the ponderosa, they can grow on dry, rocky sites. Since they often reproduce vegetatively—a grove of aspens is often produced by sprouting from the roots of a single tree—aspens are well suited to unstable or fire-swept sites. Although readily consumed by fire, aspen groves regenerate quickly from their undamaged root systems. Without periodic fire, in fact, aspens are eventually excluded from the forest composition, shaded out by the taller growing conifers.
The growing turbulence spurs me onward. Hugging the steep upper slopes of the Tower’s circular base, the trail allows a speedy orbit. The falcon continues to scream. Now along the southeastern face, I can hear the climbers shout to one another. The belly of the cloud is overhead and angry-black. Lightning flashes are now immediately followed by loud reports, sharp as splitting wood. I should turn back and drop to the nearby trail that returns to the campground, but the swell of wind in the pines and the occasional crash of falling snags is invigorating. A sudden invasion of cold air means the rain will come heavy and soon. I wonder if the climbers are as unprepared for this as I am.
In a rock crevice where the trail passes along a cliff face, an untidy ring of trash reveals the nest site of a wood rat. Called “pack rats” because of their habit of carrying off unguarded items, these big rodents adorn their nest entrances with anything from bottle caps to sunglasses. This one has amassed a fine collection of discarded gum and candy wrappers. As the first large raindrops thud down into the trail’s soft earth, I envy the animal’s protective retreat.
In ten minutes I am back at the spur that leads to the Visitor Center. If the old man is still there, perhaps I will wait out the storm with him beneath the porch roof. But I cannot see him, so I continue on to the campground. I am already soaked through anyway, so the lashing rain is no longer a threat. I retrace the section of trail I had walked an hour before. Ten minutes more and I leave the pines and enter the deserted, puddled prairie dog town.
Nearing the road, I see a car approaching slowly. As it passes I notice the old man. Leaning forward, he cranes his neck to catch a last glimpse of the Tower he had waited so long to see.
Voice of the Kingfisher
By late afternoon the storm has passed, and with the return of sunlight a rainbow arches the Belle Fourche. Taking advantage of the softened earth, the prairie dogs busily reshape their mounds, scratching dirt loose, bulldozing it up the slopes of entrance mounds, and tamping it. All but the young wear black noses. At the return of the climbers the town suspends its work, rises to alert, and chirps warning.
A meadowlark sings from a fence post near the river. Against the purple southern sky, its black and yellow vestments seem unnaturally bright, and its call in the rain-cleared air seems sharply amplified. It glides into the glistening grass. Soon the female, wearing a duller version of its mate’s tuxedo, flies up and disappears across the narrow river. When she returns, her bill is crammed with insects for her demanding young in their grass-lined ground nest.
A red-headed woodpecker, which has been shuttling between a certain cottonwood and other trees, also reveals its nest site. High up in the tree it has excavated a perfectly round hole. Leaning back on stiff tail feathers, it jerkily climbs up and around the trunk, pauses at the hole, then leans in to deliver the white grub to its squealing young.
So insatiable are nestling birds, their demands exert a significant control on insect populations. A pair of adult house wrens may log more than 1,100 daily trips to feed their young.