City Creek Nature Notes – Salt Lake City

May 28, 2017

May 24th

Birds of Concern

5:00 p.m. At dawn today, from the west half of the valley, I could see the upper slopes of Grandview Peak that feeds the stream, and they are still covered at some depth. Significantly, overnight temperatures have returned the sixites. This early evening, a summer storm front moves through from the southwest bringing warm rain and micrcobursts of fifty mile an hour winds. Under their pressure, individual trees in the canyon wave back and forth violently under momentarily black skies. The first Woods rosa blooms have opened for the season, and in the lower canyon, some Gambel’s oak leaves have reached a mature length of 5 inches. Since it is early in the evening, most birds are quiet. At Guardhouse Gate, five Warbling vireos weakly call and at picnic site 5, another is joined by a Song sparrow.

Near mile 0.6, I stop along the road to tie a shoelace. Looking up, a male mallard is swimming on the stream’s surface about seven feet below the roadside. The mallard is grazing on streamers of underwater grass that waves under the swiftly moving current.

Stink bugs line the roadside today, all uniformly standing with their abdomens pointed upward at above the centerline of the road. Given the presence of the spring birds, this is a wise resting posture. A two-inch unidentified, hair covered caterpillar crawls along the road. In a possible example of mimicry, each of its segments has a white, black and brown pattern that is nearly identical to the Variegated Meadowhawk dragonfly. Further up canyon, a one-inch beetle has two bright perpendicular orange bars on its back, and the orange tone is the same found on a Lady Bug. It is a carrion eater – the Burying beetle (Nicrophorus tomentosus). Unlike other Nicrophorus species, this beetle does not bury its carrion, but only drags it to a shallow depression and covers the carcass with leaf litter. A colony of tiny brown ants erupts from a crack in the pavement. A four inch circle contains an estimated 500 individuals that all crawl on top and over each other. About eight unidentified small brown butterflies are seen along the first mile. Their wings have a bright light-brown metallic upper side.

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Under the United States dual-sovereignty scheme, protection of endangered and other birds is divided between federal and state authorities. The federal government through the U.S. Fish and Wildlife Service has primary authority to protect both endangered and threatened bird species through the Endangered Species Act of 1973 (16 U.S.C. Sec. 1531), and with respect to non-endangered migratory birds, such as those seen in the canyon, through the Migratory Bird Treaty Act of 1918 (16 U.S.C. Secs. 703-712). The federal government is authorized to enter into cooperative agreements with States to share protective efforts for the migratory songbirds seen in the canyon through the Neotropical Migratory Bird Conservation Act of 2000 (16. U.S.C. Secs. 6101-6109). While no federally endangered species are currently known to frequent the canyon, historically, the Yellow-billed cuckoo, a federally listed threatened species, may have used the canyon (Rawley).

The State of Utah, under its sovereign authority, also designates sensitive species that are given special monitoring attention (Utah Code Ann. Sec. 23-14-1 et seq.; Utah Administrative Rule 657-48; Utah Department of Natural Resources 2015), and the State exercises that authority under a policy to “seek to balance the habitat requirements of wildlife with the social and economic activities of man” (Utah Code Ann. 23-14-3(2)(iii) (2017)). Federal threatened species and Utah state sensitive species share the common quality that a birds’ declining populations raise issues as to its continued viability. State sensitive species found in the canyon are Bald eagles and Northern Goshawks. Other State sensitive species historically, but not currently, found in the canyon include Bobolinks (Dolichonyx oryzivorus) and Ferruginous hawks (Buteo regalis) (Utah Department of Natural Resources 2015). In designating a sensitive bird species, the state circumscribes its authority to those species for which “there is credible scientific evidence to substantiate a viable threat to continued population viability” (Utah Administrative Rule 657-48; Utah Department of Natural Resources 2015). The state relies principally on the Breeding Bird survey data (May 21st, May 22nd and May 23rd) (Utah Department of Natural Resources 2015, Appendices; Sauer et al 2017).

Bird designation on the state list occurs primarily either because of global population size combined with local population trends. The State designates the Bald Eagle as a sensitive species primarily because of the size of the eagle’s continental breeding population. In 2006, there were about 10,000 breeding pairs of bald eagles left in the United States (out of a population of 70,000), and the 10 bald eagles that over-winter in Utah represent about thirty percent of all Bald Eagles west of the Rocky Mountains (Utah Department of Natural Resources 2015, Appendix A, Sec. 5.1). In using the Partner’s-in-Flight rating system, the eagle would be given a population concern index of 5 for having less than 10,000 breeding pairs. Conversely, the Bobolink have about 10,000,000 global breeding pairs, but the decline in the global and local populations is 1.6 percent per year (id, Appendix A, Sec. 5.8). The Ferruginous hawk (id, Appendix A), like the Peregrine falcon, is a recovering raptor with an estimated global breeding population of 80,000, or a population concern index of 4. But, due to recovery management efforts, its population is increasing. That both the Bobolink and Ferruginous hawk are believed to have been widely present in Utah historically, but now are largely absent from the state also supports their Utah sensitive species status (id, Appendix A).

In contrast, other birds that receive a private Conservation Concern Index of 13 like the Virginia’s Warbler and the Plumbeous vireo and that are found in the canyon are not designated by the State. Although they have locally declining population trends, the Virginia’s Warbler has a global breeding population of about 400,000 pairs and although the Breeding Bird Survey found only 192 pairs of Plumbeous vireos in the Intermountain West (Sauer et al 2017), the Plumbeous vireo has a global population of about 2,700,000. The Peregrine falcon is another bird not designated on the state’s list (Utah Department of Natural Resources 2015). The Peregrine was delisted by the federal U.S. Environmental Protection Agency in 1999, and the global breeding population of Peregrines is about 93,300. But there only about 90 breeding pairs of this still recovering raptor, or a sufficiently small population that it could wiped out by a set of determined illegal hunters in a few weeks. Although I feel some of these Utah state sensitive bird specie designations to be inconsistent, e.g. – the Boblink but not the Plumbeous vireo is designated, they evidence a process in place, albeit an imperfect process that operates under considerable uncertainty, to monitor and assess potential crashes in bird populations.

Uncertainty in the state-of-knowledge about bird populations and in the process of designating them for more intensive monitoring is also unsettling. Conversely, the signs that these researchers and their models provide allow us to act more thoughtfully than simply relying on political beliefs and folk-tales about nature’s ability to cope with change. That a considerable multi-state monitoring effort coupled with recovery planning exists is cause for celebration and not cynicism. That process has led to the ongoing recoveries of Peregrine falcons and Ferrigunous hawks. But even with all this effort, I find it hard to let go of the sense that we are pulling at the strings of nature’s web, and like Plato’s prisoners in his allegorical cave described in the Republic, our scientific efforts and mathematical models of specie risk give only a limited indirect view of a truer complexity that we do not understand.

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On May 24, 2007, 200 persons attend the annual Memory Grove clean-up (Salt Lake Tribune). On May 24th, 1996, veterans groups plan to gather at Memory Grove for Memorial Day. On May 24th, 1920, the North Bench Improvement Association Chairman G. A. Iverson published an artist conceptual drawing for a park in lower City Creek including a viaduct across the canyon at 5th Avenue (Salt Lake Telegram). On May 24th, 1913, members of the Rotary Club and City Commissioner Korn plan to tour the proposed route of a scenic highway up City Creek Canyon and into Morgan County (Salt Lake Tribune). May 24th, 1907, the Salt Lake Tribune urged the creation of reservoir dams in City Creek and Parley’s Canyons. On May 24, 1903, the Salt Lake Tribune overviewed many canyon drives around Salt Lake City, including in City Creek Canyon. One photograph includes Shippler’s image of a carriage going up a heavily wooded City Creek track (id). The article also relates a parable and legend about a young man who located a lost gold mine, and contrary to his Mormon bishop’s advice, spent his life in a vain attempt to relocate it. His futile search was described as his “punishment for his disobedience to the mandate of the prophet revealed by God” (id). The Tribune noted that hundreds of City residents go into the canyon on the weekends.

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).

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