City Creek Nature Notes – Salt Lake City

May 10, 2017

May 7th

Iridescent butterflies

4:00 p.m. Red-ozier dogwoods are blooming. Gambel’s oak trees at picnic site 1 have leafed-out to between two and four inches, but some of these oaks higher at mile 1.0 have no leaves. At Pleasant Valley, grasses are twelve inches high and move in waves in response to breezes. The high canyon walls are all covered in these green waves. Along the Pipeline Trail, red maples have leafed out to four inches. Mullein stalks are beginning to rise. Along the Pipeline Trail, 20 or 30 birds can be heard, but only yesterday’s male Black-chinned hummingbird puts in an appearance at its usual post on the powerline. No soaring raptors are seen today.

The thirty or forty butterflies in the first mile are dominated by Orange Sarah tops and Desert Elfin (Incisalia fotis fotis) butterflies. Below picnic site 1, an unidentified red-brown caterpillar hangs from a Box Elder tree by a twenty-foot long silk thread, and as the wind blows it sways back and forth in large five foot arcs. It does not know whether to go further down or up. At picnic site 3, an unidentified beetle lites onto a table, and in a ray of sunlight, a patch on its back radiates a bright lime green. Near mile 0.5, a small black ant drags a dead lime green caterpillar back to its nest. Along the Pipeline Trail, a Common sulphur butterfly moves between and drinks from Arrowleaf balsamroot blossoms, and more than ten Stink bugs are active on the trail. I miss nearly stepping on one that is laid out, legs splayed wide, on the trail. My foot alarms it and it springs up and lands in a defensive posture. Back at the Guardhouse Gate, I notice a Cabbage white butterfly fly into a bush, inexplicably struggle, and then frenetically fly off. Close examination shows the circular web of an orb weaver spider (Araneus sp.). This unidentified spider has wonderful orange, white and black spotting on its abdomen, but I am unable to photograph. My autofocus camera only sees the background and refuses to make a sharp image of the tiny spider in the foreground.

Just before Guardhouse Gate, two mallards, one-male, one-female, are standing right next to the road unafraid of humans. The male is half-asleep and appears contemptuous of people. The female is feeding on roaches under the leave litter. She digs through the leaf litter and rapidly opens and closes her beak. This separates the chaff of the dead leaves from the wheat of the small bugs. In the Guardhouse Gate parking lot, an immature Rock squirrel is browsing in the middle of the road. I pull out the car and chase him back into the brush with flashing lights and a honking horn. I am teaching the squirrel to be afraid of cars. For this squirrel, there will be no repeat of finding it dead on the road, as seen last summer.

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Butterflies also have ultra-violet vision used in differentiating flowers, but some may use iridescence and the uv spectrum to communicate between themselves (Doucet and Meadows, 2009; Buront and Majerus, 1995). Butterfly wings are covered in miniature scales that like the feathers of birds make colors have diffraction. In 1968, an experiment of Obara and Hidaka at the Tokyo Institute of Agriculture and Technology demonstrated that male Cabbage White butterflies locate their mates primarily by visual clues (Obara and Hidaka, 1968). They sealed females and male dummy butterflies in Petri dishes in order to prevent the males from finding their mates by smell. Since male and female Cabbage whites look nearly identical in the visual spectrum, how could the males tell them apart? Ultra-violet photography revealed that the wings of female Cabbage whites are white or patterned and the males are totally dark. On 2008, Obara and colleagues repeated this experiment, but noted that females have subtle changes in their UV color during the summer, and males preferentially mate only with the summer-colored females (Obara et al 2008). In 2000, Knuttel and Fiedler at the Universitat Bayreuth suggested that this was not a universal principle. They found that many species of butterflies appear different in the visual and uv light, but the variations within species where larger than between species and were not so great as to be a means discriminating between or within species (Knuttel and Fiedler, 2000; Buront and Majerus, 1995, same). Iridescent differences in the visual spectrum is dominant in butterflies when distinguishing between individuals (id). Butterflies also have iridescent colors in order to confuse predators or to warn them that the insect is poisonous (Doucet and Meadows, S124).

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On May 7th, 1996, Utah Partners in Flight plan migratory bird watching in City Creek Canyon (Salt Lake Tribune). On May 7th, 1910, the Salt Lake Telegram published a photographic spread on City Creek Canyon and extolled the canyon’s virtues. The Telegram argued for a City Commission proposal to widen the road using prison labor and to make other park improvements (id).


April 13, 2017

April 13th

Insect Revival

1:00 p.m. The jet stream has diverted storms to the north of the canyon, and thus, there will several days of sunshine and temperatures in the seventies like today. The insects sense this change, and in addition to the usual reprisal of Mourning Cloaks and White Cabbage butterflies, new insects gone since the fall reappear. There is a White cabbage like butterfly but with bright orange triangular wing tips: a Sara Orange Tip (Anthocharis sara). Two yellow Anise swallowtails fly up the road, but one is now full grown (April 1st). There are two new bees, one black and one brown, that restlessly hover and zip by me at several points along the first mile road. Both are two fast to identify, but after some attempts to follow them, two examples land and briefly rest. The black bee may be a Western leafcutting bee (Megachile perihirta). The brown-haired one remains unidentified. A Brown Daddy-long-legs (Phalangium opilio) scurries across the road. Ants are again active, and the first flies appear. Below Guardhouse Gate, some broad leaf plants have been reduce to pock-holed skeletons. After examining several plants, at the base of one are black caterpillars barely one and one-half millimeters long by one-quarter millimeters in diameter.

By afternoon, the heating of the valley-floor cold morning air to the seventies contrasts with the air in the high mountains that is still a degrees above freezing creates up strong canyon high winds. More broken twigs litter the road, and for the second time, I jog up canyon, only find when returning down canyon, a 4 inch diameter and 12 foot long broken branch laying across the road.

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On April 13th, 2007, City Creek Canyon was closed while solid waste was removed from the water treatment plant (Deseret News). On April 13th, 2006, the Salt Lake Tribune does an article on how dog interactions during canyon walks are important to a dog’s socialization (Salt Lake Tribune). On April 13th, 1915, City Commissioners inspected the proposed Pleasant Valley reservoir site in City Creek Canyon (Salt Lake Tribune). On April 13, 1915, the Wasatch Hiking Club reported for its initial hike, club members traveling up City Creek to the Forks (Utah Daily Chronicle). On April 13th, 1910, the Commercial Club proposed that the City hire an expert to plan a system of parks for the city (Salt Lake Telegram). With respect to City Creek, the Telegram editorialized that:

“City Creek can be made a wonderland, or it can be spoiled. City Creek Canyon and the heights just above can be made a place of enchantment through all the summer and more especially in the long autumn. In the hands of a chump, it can be spoiled. . . .” (id).

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