City Creek Nature Notes – Salt Lake City

June 25, 2017

June 25th

Fishing spiders

5:00 p.m. The first mile of road has turned into a green tube, and the garland of butterflies described on June 15th and June 22nd continues. The sky is clear and the air calm. Trees overhang above and views of the stream are obscured by thick underbrush except at picnic sites. The stream can also be accessed at small breaks made by anglers or at small natural breaks. There about ten of these breaks along the first road mile. I force myself through several of the breaks and look down to enjoy the cool, transparent stream. At each I find various types of spider webs: disordered tangle webs, sheet webs hung low just above the waterline, and the circular webs of Orb weaver spiders (Araneus sp.). Paradoxically, I see no spiders today, but their webs are full of hapless arthropod victims.

Lining the stream banks at these breaks are Bittersweet nightshade plants (Solanum dulcamara) a.k.a. Climbing nightshade with deep blue blossoms. These plants hug the stream’s steep banks and vertical rock retention walls, and they grow just above the waterline. At a few places along the first road mile, they incongruously protrude from the understory of serviceberry bushes (Amelanchier sp.), and there they are noticeable because their colorful blossoms are one of the few flowering plants that are left after the spring flower explosion. The Nightshade’s blossoms are either shriveling or extend vibrant yellow cones surrounded by blue petals. In the fall, these will yield bright red fruit.

Looking up from the stream and into the thick green sub-story, there are butterflies everywhere. They are the usual suspects for a canyon spring and early summer: Cabbage white butterflies, Western tiger swallowtails, Mourning cloaks (Nymphalis antiopa). These are now joined by White Admiral butterflies and by Common whitetail dragonflies patrolling overhead. I am used to seeing this floating butterfly assemblage traveling linearly on their feeding searches along bushes on the road’s sides, but here they fly in their natural setting. The butterflies follow large spiral flight paths broken by and traveling through the dense shrubs. In this setting, their frenetic sharp turns and chaotic shifts are necessary to navigate this complicated scene, and this explains these seemingly purposeless motions on their flights over the road. In this manner, the butterflies explore every possible hiding place in which a flowing blossom might be found.

At each of my stops along the stream, I see about five butterflies, and together with butterflies along the road, I estimate that there about 100 butterflies in the first mile road. Two Painted Lady butterflies (Venessa cardui) are also patrolling the roadside bushes. What flowering plant these butterflies are searching in the shurb understory is a mystery. The daytime flowering blossoms of spring are past, and only a few Foxglove beardtongue flowers remain open producing nectar. The only substantial flowering plant left is Yellow sweet clover. But the stands of this weed that line only the roadsides are fading, and on any one plant only one-third of the blossoms found at their peak are viable.

The fierce post-solistice sun begins to affect tree leaves. One or two Gambel’s oaks and Norway maples have a brace of leaves that are browned and shriveled at the edges. Once damaged, their leafs curl up, and the crabapple tree at the upper end of Pleasant Valley near mile 1.7 shows similar signs of stress. But the deciduous trees’ principal defense against the loss of water from heat and sunlight is a waxy layer on the upper surfaces of trees. This is best seen on the leafs of the western River birch trees. At the right angle to the Sun, their canopy flashes dappled green light for leafs titled away from the light and a blinding silver-white light for those at appropriate angle of reflection. University of Sussex ecologist Hartley notes that the waxy layer provides another benefit: it is some tree’s defense against caterpillars (Hartely 2009). Although caterpillars have evolved specialized feet to grasp leaf surfaces, caterpillars have a hard time walking over the wax layer, they fall off, and the plant is preserved. This may explain the caterpillars sometimes found along the road in the last week. I had supposed the caterpillars had crawled onto the roadway, but perhaps they have slipped and fallen from above.

Returning down canyon from milepost 1.5, insects are backlit by the Sun, and this makes them easier to see. At mile 1.1 near the entrance to lower Pleasant Valley, 30 to 40 Common whitetail dragonflies are circling between 50 and 100 feet above ground. Between the road surface and fifty feet, there are none. In cool places beneath the shade of trees, the prey of the dragonflies, groups of up to 100 gnats float. A small, immature desert tarantula (Aphonopelma chalcodes) scurries into the bushes.

Also mile 1.1, I hear raptor screams, and this repeats my earlier experience of June 21st. They are the unmistakable calls of two Peregrine falcons (Falco peregrinus). This time I travel back up canyon to get a better view, and below the eastern canyon wall near mile 0.8, more than a quarter-mile away, two peregrines are driving a smaller bird away from the canyon sides. There loud screams travel coherently through the calm summer air. This may be where the peregrines are nesting this season, but that side of the canyon does not have the steep cliffs found on its western walls. I note to watch this area closer to see if a nest can be confirmed.

* * * *

Per Thoreau’s “Journal” on June 25th, 1852, he sees a rainbow in the eastern morning sky. He opines that younger birds are duller in color in order to protect them from predators. He hears a bobolink and a golden robin. He sees wild rose and butter-and-eggs. He notes that in cool air, the ridges on distant mountains are more distinctly seen. He describes a moon-light walk. On June 25th, 1853, he finds two bushes of ripe service berries and associated cherry birds. On June 25th, 1854, he sees a bittern. On June 25th, 1858, he sees two or three young squirrels playing. He observes how objects including grass and water skimmers cast lenticular shadows on the bottom of a river. He again notes how the lighter undersides of leaves illuminate dark sprout forests.

* * * *

On June 25th, 1946, City Water Commissioner D. A. Affleck closed all lands in lower City Creek and above 14th Avenue to entry in order to prevent the possibility of grass fires (Salt Lake Telegram). Campfires were prohibited in upper City Creek Canyon (id). On June 25th, 1913, City officials plan to inspect the headwaters of Salt Lake valley canyons for water purity as part of a plan to develop more water sources (Salt Lake Telegram). On June 25th, 1896, new silver and lead ore bodies were discovered in upper City Creek Canyon about one mile from the old Red Bird Mine on Black Mountain (Salt Lake Herald). Mining work continues at other mines in the Hot Springs mining district, which includes City Creek (id). On June 25th, 1892, an old, destitute woman who had been living in cave in City Creek Canyon was sent to the hospital (Salt Lake Times).

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2 Comments »

  1. This blog is extraordinary. I find that I look forward each day to the new post. Thank you.

    Comment by Andrew Cliburn — June 26, 2017 @ 7:17 pm

  2. Thanks, Andrew.

    Comment by canopus56 — June 27, 2017 @ 4:27 pm


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