The Riparian Underworld

I parked at the Camino del Cerro bridge, over the Santa Cruz River in Tucson, at about 7:15 a.m. I didn’t have much time but I wanted to connect with the river. It’s a funny underworld sitting below usual Tucson birding and daily life.

Walking off the bridge at Camino del Cerro onto The Loop Trail, I wondered what I would find along the Santa Cruz River. I could hear almost nothing in the river because of the cars rushing by. Three lesser goldfinches had perched on a snag for a moment, and I heard one Abert’s towhee tooting a call. Some rock pigeons flew by.

I descended under the bridge on the paved bicycle and pedestrian trail, where it reached only feet from the river’s sandy bottom. I leaned down and passed between the bars of the dull red-painted railing, and dropped the last 4 feet down the steep embankment. I was in the shade of the bridge on the sand, with the river’s weak flow about 10 yards away.

Whenever I get down to the river I feel like I’ve gone below the city’s surface. It’s like being injected into a major artery, below the skin. The bright morning sun and the sounds of the street are dulled and the sound of slowly passing fluid becomes dominant.

There were no owls perched in the bridge supports, something I had wondered about. Still no barn owl on my year list.

But there was abundant evidence of recently departed cliff swallows on the sides of the bridge’s understructure. Mud nests were plastered to the upper part while upward pointing cones of bird poop lined the ledge below the nests.

Down here I heard a few more birds, but less than I would have heard a couple of weeks ago while fall migration was more vigorous. A warbler chipped softly. I chased it but couldn’t get more than a fleeting shadow of it among willow leaves. Then a zippy little call made me think of lazuli bunting. I began to rethink the earlier chip and the grayish shadow I had seen, but the shadow flew across the river and out of sight.

All in all, on this morning there was more evidence of people than birds. The metal girders creaked above me as people passed over on their way to work. There was trash, quite a bit of trash. Some of it was fresh, left by people passing by or homeless sleeping under the bridge. On this morning there was somebody camped under the east end of the bridge on a high ledge, near where the bridge meets the east bank of the river. There was a makeshift curtain at one end made of a white sheet, letting people know that spot was taken. I could just see him, or her, wrapped in something and sleeping near a backpack.

Below the sleeping perch were plastic bottles, food wrappers, shoes, and assorted bits of clothing. It looked like evidence of far more than just one person on one night. Like a lot of people, homeless don't "take only pictures, leave only footprints."

Other trash had come from upstream, like a green plastic chair I found wedged into the trunks of a willow. Perhaps it had been cast into the river by some frustrated soul. Or maybe it was brought down to the river somewhere upstream by other homeless people, hiding their temporary camps in the tamarisks. It could also have washed out of a yard in one of the heavy downpours in July, floating along a street, down a storm drain and into a momentarily frothing river.

A shushing house wren call caught my attention. It momentarily appeared in the leaves of a tamarisk before going back out of sight. A mourning dove passed over low and fast, as they often do.

Other people, besides the homeless, had spent time under the bridge as well. The gray concrete pillars holding up the bridge had been decorated according to somebody’s—multiple people’s—ideas of color and identity.

As I emerged again to street level, a dot on a tall transmission line tower turned out to be a peregrine falcon. I was back in the bleak and dry historic floodplain, full of predatory activity, human and aerial. The falcon was rubbing his bill on the tower, or perhaps on its own feet, rubbing off the remains of an early bird special.