City Creek Nature Notes – Salt Lake City

May 19, 2017

May 19th

Sun Dappled Stream and Butterfly Hosts

5:15 p.m. The first mile is almost fully leafed-out and the understory is well-developed. The stream, which throughout the winter is fully visible, can now only be caught in partially obscured glimpses where the trees and underbrush break. Through those screens, the low, warm, yellow light of the falling Sun glides and lands on clear surface of the stream in round dapples. Today is an advance hint of the stream during the summer canyon summer which is now one month away. The key today difference is the stream runs high, but like the summer it has turned transparent. The stream has fallen about four inches overnight, but the water is pure. The spring period in which the stream runs, according to the City’s 1895 Mayor Baskin, as “very muddy, unwholesome and unpalatable water” (Feb. 6th) has passed. Rocks can clearly be seen through the rushing waters between its windowed surface.

It remains unseasonably cold – in the low fifties in the canyon and near freezing overnight – from the passage of the last storm. People in the city complain about it constantly having wearied of prior long winter season, and in the canyon, this has emptied the road. The cold has also suppressed the birds and the butterflies. A lesser total of 15 birds are heard along the road and the Pipeline Trail. Only a single Western tiger swallowtail and some gnats make an appearance.

A single Red-tailed hawk floats one hundred feet over the parking lot. At picnic site 1, my evening Lazuli Bunting is perched on the tallest tree. Along the Pipeline Trail using audio recordings and spectrograms, I am able to identify the songs of three of the some ten song birds, i.e. – a , a Warbling vireo, and a bleating evening “keah” from a Northern flicker. I have begun to make some progress into understanding the canyon birding soundscape (May 6th).

When the butterflies rally in next week’s rising heat, what will the adult butterflies and their caterpillars eat? I can find nothing specific for Utah, and therefore, using sources for other States, I compiled a list of possible hosts and food sources for some of the recently seen butterflies. It is a starting point, suggestive, and not authoritative. Although the butterfly spring peak has passed, I will have to take better notes on which butterflies are associated with which plants.

List of Possible Plant Hosts for Butterflies and Their Caterpillars in City City Creek Canyon
• Mourning cloak butterfly. Adult: Tree sap from Gambel’s oaks. Willows, elms, maple and ash trees. Caterpillar: The same plus aspen and river birch.

• White cabbage butterfly. Adult: Nectar from mustards, dandelion, asters, clovers and mints. Caterpillar: Same. There are various analogs to these plants in the canyon.

• Painted lady butterfly. Adult: Yarrows, thistles, sagebrush, sunflowers, milk-thistle, stinging nettle. Caterpillars: Same plus milkweed.

• American lady butterfly. Adult: Sagebrush, thistles, Wood’s rose and vetches. Caterpillar: Sunflowers, burdock, milkweed and aster.

• White-lined sphinx moth. Adult: Nectar from columbines, larkspurs, clovers, and thistles. I have seen Giant sphinx primary feed in the spring on dandelion. Caterpillar: apple and elm trees.

• Spring Azure. Adult: Dogwood, and berry plants.

• Common sulphur butterfly. Adult: Clovers and vetches and nectar from many plants. Caterpillar: Clovers and vetches.

• Sara Orange Tip butterfly. The Sara Orange tip is similar to the Julia Orangetip butterfly (Anthocharis julia browningi). For the Julia – Adult: Flower nectar from rock cresses, violets, and mustards. Caterpillar: Rock cresses.

Source: Dallas County Lepidopterists’ Society (2008). Host Plants by Butterfly (Web).

* * * *

University of Utah Meteorology Professor James Steenburgh recommends a new climate change application to examine whether local daily weather patterns are unusual. People tend to mid-interpret unusual cold and hot seasons as indications either for or against the existence of global warming, regardless of the separate issue of whether it is human-caused or not. The University of Maine and its Climate Change Institute has deployed an internet application that shows each day, a map of the globe and how surface temperatures at each point on the Earth differs from the average temperature at that point for that day over the last seventy years (University of Maine 2017a). A large dark blue spot on the map hovers over Utah, Colorado and Wyoming, indicating that the Intermountain West is 18 degrees Fahrenheit cooler that normal. The coldspot sits in the cradle of a “U” shaped dip in the jet stream. Overall, the globe is about 0.5 degrees warmer. The lesson to be learned from the map is even when their are local anomalies in weather, such as in the canyon today, the world average remains steady. The world average is the indicator of global warming and not local conditions.

* * * *

On May 19th, 2008, the City closes City Creek Canyon to spray herbicides on the invasive Starthistle plant (Salt Lake Tribune, May 20, 2008). On May 19th, 1906, the City tankman and former city councilman George D. Dean, was found dead at the Water tankman’s house in City Creek Canyon (Deseret Evening News, Salt Lake Tribune, May 20th, 1906). On May 19th, 1875, seminary students went picnicking in City Creek Canyon (May 19, 1875).

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