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).

March 14, 2017

March 14th

Flooding of City Creek’s Delta – Part V

1:30 p.m. An early spring arrives; the temperature is in the seventies. The canyon continues to be flooded with walkers, runners and bicyclists during the middle of a workday, and this may be driven in part by the fact that the local university is on spring break. Near mile 0.4, I watch a large raptor soaring next to the high cliff walls on the canyon’s west-side for several minutes, and then it dives into a nesting site in cliff wall. Raptors are known to nest there through mid-June. Although trees continue in their somnolence, insects respond instantly overnight. I estimate 500 Box Elder bugs are active in the first mile. Their abdominal segments are a bright red-orange, and this aids them in locating each other for their many mating orgies that I pass on the road. Gnats are in abundance, the first houseflies appear, and I see the first wasp of the season. I count five butterflies of four different types. The first is a large black butterfly with a white trailing edge, probably a Mourning Cloak (Nymphalis antiopa), and the second mid-size butterfly with black wings and a trailing red-orange band is probably an early Red Admiral butterfly (Vanessa atalanta). A White Cabbage butterfly is seen on the Pipeline Trail. The fourth is the inverse of the Red Admiral: orange-winged with a black trailing edge. These are early hatchlings. The annual butterfly explosion, in which up to one-thousand butterflies can be seen on the road, is several weeks away. One regret that I have from the winter is that despite my searches, I was unable to locate any butterfly or moth cocoons hanging from trees. That is where the butterflies hibernate through the winter.

Near mile 0.4 where the Gambel’s oak forest spreads up the western canyon slope, the oak thicket hides small birds, but I can hear about five distinct calls. Only a robin’s call can be definitely identified. Along the stream, a startled thrush runs under the tangle of a bush’s roots. I jog down the Pipeline Trail. In April and May and after the oaks renew their leafs, smaller migrating song birds can be seen perching on the electrical power lines that parallel the trail, but today, I see none. Below Shark Fin Rock near trail mile 0.5, a mid-sized bird, screened by the trees, calls with a loud “chirp-cheep”. I cannot see it, but from the changes of its calls’ levels, I can tell that the bird is standing in place and rotating around, probably advertising for a mate.

In Thoreau’s “Journal” on March 14th, 1854, he hears a large flock of song-sparrows in the trees. On March 14th, 1855, he sees sparrow tracks in the snow leading to blue curls, a plant that contains dried seeds.

The weather and increased ability to forecast flooding works against City residents’ tendency to forget extreme events. The National Weather Service, the National Soil Conservation Service and the U.S. Geological Survey maintain an extensive system of flood gauge monitors and a sophisticated national flood prediction system, the Advanced Hydrographic Prediction Service, the data from which is publicly available (U.S.G.S. 2017, NSCS 2017, NWS 2017b, 2017c). The NWS regularly publishes probability predictions of annual flooding whenever the snowpack is high (Salt Lake Tribune, April 29, 2011). For example, although 2017 has not resulted in flooding in City Creek, flooding in northern Utah towns like Tremonton fill the news.

When City Creek returns to flood its delta, the waters will find a much changed city. In the 2000s, when the North Temple shopping district was rebuilt at the cost of over $1 billion USD. Since 1983, the business district has seen construction of numerous large buildings on both sides or Main and State Streets, and pursuant with City policy, each has constructed many large underground parking lots. For example, between South Temple and 100 South and State and Main, the entire 10 acre block now contains a multi-level underground parking structure. The same is true between 200 South and 300 South between State and Main. The doors that close off entry to these underground cavities are simple thin roll-down affairs that will not keep flood water out. Although during the 1983 flood, sandbagging kept water out of the then only underground garage, when City Creek again floods the downtown, these underground lots will be susceptible to filling with water, and the economic cost of the next extreme flood – which still can overwhelm the post-1983 increased capacity of the storm water system – will be much higher.

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