City Creek Nature Notes – Salt Lake City

June 27, 2017

June 26th

Wasp Explosion and Return of the Water Striders

4:30 p.m. It reaches 100 degrees in the valley; the estival heat has returned. The stream level continues to decline, and the pond at picnic site 5 is beginning to reform under the higher spring run-off. At its banks, a wetted sand and silt line has developed. Here, about fifteen Western Yellowjacket wasps land and take sips of water. In a small pocket of calm water, the season’s first water strider (Aquarius remigis) appears (Sept 12th). A similar scene is found at the water seeps below picnic site 6. Checking the stream and its opposite banks at several times along the first mile, I find areas with thirty or forty Yellowjackets. One one bank,a Western tiger swallowtail butterfly lands also seeking to take a drink. Individual Yellowjackets start dive bombing the swallowtail, and after the fourth, the butterfly move down canon. What the yellow jackets are eating is unclear. I find one crawling over a roadside weed that no longer has flowers. It crawls to the juncture between a leaf and the plant’s main stalk where a white liquid oozes out. The wasp spends a minute drinking before flying off. I estimate that there are about 400 wasps along the first mile of road: enough for two colonies. At picnic site 1, a Prairie rose (Rosa setigera), a cultivar, with delicate pink blossoms that surround fifty stamens, blossoms.

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Per Thoreau’s “Journal” on June 26th, 1853, he notes that air is warmer after a thunderstorm. He describes a summer sunset and a faint afterglow three minutes after the sun falls below the horizon it lights up low clouds in the sky. He notes how in summer light, the outlines of mountain ridges are more distinct. On June 26, 1856, he describes the last remaining Native American, a seventy-year old woman, who lives alone in his neighborhood.

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On June 26th, R. J. Robinson, a consulting engineer who obtain water rights in City Creek Canyon, offered to sell his rights to the City (Salt Lake Tribune). On June 26th, 1908, the Salt Lake Tribune reported that Chin Wo, who had been sentenced to the City Creek chain gang road crew for vagrancy and who was believed to have mental health issues, attacked police guard Kast with a shovel.

May 22, 2017

May 22nd (Revised)

Continental Scale Bird Population Trends – Part I

(Science Section Revised May 28th.)

1:30 p.m. It will be a good day. As I ready to leave for the canyon and before even starting the car, a brilliant red House finch lands on a nearby telephone wire and sings happily for five minutes. Bright sunlight floods the canyon, and spring life explodes. There is too much to see, and I am overwhelmed. The roadside heats up with smells of fresh growth, and it mixes with the crisp cool air that rises from the transparent, chilled water of the swift stream. In the first mile, fifty birds are active, all singing in cacophony. The red ozier dogwood bushes are covered with small one-half inch bees with yellow and black abdomens and similarly miniature wasps with black and white striped abdomens. The first Western Yellowjacket wasp of the season lands. Nine Yellow swallowtail butterflies line the first mile with Mourning cloak, White cabbage, Painted Lady, and Spring Azure butterflies. Two Blue-eyed darner dragonflies fly above the road, and one unceremoniously defecates as it passes.

Immediately past Guardhouse Gate, three Warbling vireos exchange calls from the surrounding trees. Along the road to mile 0.3, I can distinguish about fifteen bird songs and calls, but by sound, I can identify the American robin, a Mountain chickadee, the Black-headed grosbeak, and the Song sparrow. A small Blue-gray gnatcatcher (Polioptilidae Polioptila caerulea) jumps parallel to the road along oak branches. Black-chinned hummingbird wings beat loudly.

At the bend in the road above picnic site 3, there is another riot of bird songs in a small cluster. Songs of the House finch, Mountain chickadee and others blend together. Then a blazing Yellow warbler comes of the screen of trees and lands in a nearby branch. The warbler leaves and finally, a Western scrub jay lands on a another branch. I play a recording of one of its kind squawking, the blue shouldered bird replies. This way we have an odd conversation. There is more, but this is enough.

This is the green explosion that the vernal season (February 16th) has been building to since the first of May.

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Parrish, Norvell and Howe’s Utah bird study covers one state – Utah (Parrish et al. 2007; Novell, Howe and Parrish 2005), but birds are international travellers. Olsen’s Pacific Flyway data is international but regional (Olsen 2017). Because of their dispersal, bird trends also need analysis on the continental scale. In 1966 in response to DDT’s impact on birds, the U.S.G.S. and the Canadian Wildlife Service began the first North American continental Breeding Bird Survey (BBS). However, design of the BBS did not cover weighted areas of differing habitat types (Bart 2005; Parrish et al. 2007 at 11). All survey sites were along roads, and this introduced a bias that would not allow for the study of how changes in habitat affects bird populations (id). Acknowledgement of the need to have coordinated continental scale non-game, longitudinal bird population data led to the establishment of the Partner-in-Fight Working Group (Bart 2005) to supplement the Breeding Bird Survey, and Parrish, Norvell and Howe’s work on Utah riparian habitats was part of the Partners’ system. Governmental agencies, including Utah, consolidate results into the national Breeding Bird Survey database (Sauer 2017; Pardieck 2016). Both the BBS and the Partners-in-Flight programs focus on professionally trained biologists working for or associated with many governmental agencies collecting high quality data by conducting transect surveys over time at the same sites.

Through 2015, the Breeding Bird Survey shows a declining population at 1.4 percent per year in its Western region (Sauer 2017). Plumbeous vireos decline at 2.3 percent per year.

Since the 1990s, concerns grew over what impact climate warming might have on bird populations and a need was perceived to develop management tools to early identify adversely effected bird species, and a management tool, the Partners-in-Flight the Conservation Concern Index was develop to provide guidance under the conditions of uncertainty in estimating local and global bird populations and their trends. The Partners-in-Flight methodology rates stresses on bird populations for 1,154 bird North American bird species (Panjabi et al 2012) based on five non-dimensional, ascending scales ranging from 1 (least concern) to 5 (most concern). The five indices are global population size, breeding geographical distribution, non-breeding geographical distribution, threats to surviving the summer breeding season, threats to surviving the non-breeding season, and population trends, and the combined indices yield a maximum total score of at most 25 denoted as the “Conservation Concern Index”.

Of the five indices, the global breeding population size is the most sensitive. It varies by a geometric growth rate of 10 denoted by a logarithmic index:

5 – World breeding population is less than 50,000 or 5 x 10^4.

4 – World breeding population greater or equal to 50,000 (5 x 10^4) and is less than 500,000 (5 x 10^5).

3 – World breeding population greater or equal to 500,000 (5 x 10^5) and is less than 5,000,000 (5 x 10^6).

2 – World breeding population greater or equal to 5,000,000 (5 x 10^6) and is less than 50,000,000 (5 x 10^7).

1 – World breeding population greater or equal to 500,000,000 (5 x 10^8) (Panjabi et al 2012).

The global breeding distribution index is the second most sensitive. It varies by a geometric growth rate of 3 denoted by a logarithmic index. An index of “5”, or highest concern, corresponds to 80,000 square kilometers or a U.S. state size of about 300 kilometers square. A breeding distribution index of “1”, or least concern, corresponds to 4,000,000 square kilometers, or a continent-sized 2,000 kilometer square(Panjabi et al 2012).

The Populations growth index is the least sensitive. An annual growth decline rate between 0 and 15 percent is rated “3”. Only crashing populations with a growth rate of greater than 50 percent are have an index of “5”.

Logarithmic risk indices are intended to overcome human compression bias, i.e. – our tendency to misinterpret risk over a large range of outcomes (Adams and Smith). Humans overestimate the risk of rare events, like botulism, and under estimate the risk of common events, like heart attack (id) and many natural processes, for example from our hearing and sight, increase sensitivity by a geometric scale. Thus, a logarithm index is a useful abstraction, but it is still often misperceived. If a risk level is expressed in terms of raw data, e.g. a world population breeding size of 50,000 to 500,000,000, this lends to unwarranted accusations of overstating for conservation. Conversely, when confronted with a logarithmic index, the natural human tendency is to erroneously interpret risk as an arithmetic sum. The earthquake Richter scale is a useful, common analogy. An earthquake of 5.0 on the Richter scale will shake the picture frames on your walls, but an earthquake of 7.5, will turn your home into a pile of sticks. The effects are perceived as additive, but in reality the effects are exponential.

To supplement the governmental North American Breeding Bird Survey by applying the Panjabi et al criteria on a global scale, private groups and industry from the North American Bird Conservation Initiative (NABCI). NABCI analyses are reported in annual glossy “North American State of the Bird” reports, – e.g. North American Bird Conservation Initiative (2009) and North American Bird Conservation Initiative (2016a). Another useful form of the their results is the annual NABCI Assessment Database, a spreadsheet that allows the user to sort and select birds by risk and habitat North American Bird Conservation Initiative (2016b). The mean of the index is 11.5, and a Conservation Concern Index higher than 13.5 suggests a high level of concern for which further study and action should be taken. A Conservation Concern Index (CCI) of 8.5 to 13.5 denotes moderate concern. This continental scale study provides insights into future threats that might change the currently stable bird diversity and populations totals seen in the canyon. But again, the CCI is a management tool and it does not report additive risk. Because its two key component scales, global breeding size and global breeding area, are logarithmic, the CCI scale conveys an expert opinion of a geometrically or exponentially increasing risk.

Two spring species that are regularly seen in the canyon (May 6th, May 20th) have CCI’s of 13 at the borderline of high concern: Virginia’s warbler and Plumbeous vireo. Others in the moderate concern category and their concern indices are: Broad-tailed Hummingbird (12), Steller’s Jay (11), Dusky Flycatcher (10), American Dipper (10), Black-chinned Hummingbird (10), Mountain Chickadee (10), Townsend’s Solitaire (10), Lazuli Bunting (9), Northwestern Crow (9), Orange-crowned Warbler (9), Western Scrub-Jay (9), and the Western Tanager (9). One commonality between these 13 species of 149 known to visit the canyon are that their non-breeding season ranges are in the southern Mexican highlands or the Pacific Coast lowlands. In short, land development in distant places might reduce their annual appearance in the canyon. But these results should be read in context. The NABCI indices for species found in the canyon generally indicate there is low concern of immediate threats to most species. The diversity of bird species in the canyon is stable. The NABCI “State of Birds” reports are not a trend-based forecast, although their short annual narrative report incorporates conclusions from Christmas Bird Count trend studies by the Audubon Society and governmental Breeding Bird Surveys.

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On May 22nd, 1914, the newly completed scenic automobile drive up City Creek and along 11th Avenue to be called Wasatch Boulevard will be opened to the public (Salt Lake Tribune). Other park improvements include the new Thirteenth Street Reservoir Park and adding lawn areas to Liberty Park (id).

October 13, 2016

October 13th

The Moth Who Wore Pink Pants

6:00 p.m. The overnight cold leaves faltering insects on the road, and this aids in identifying flying insects that are otherwise too fast to see or too uncooperative to pose for a portrait. In the last few days, four have landed on the road.

The Pepper-and-Salt Moth (Biston betularia) is an example of evolutionary camouflage. Whether on the road or on a tree trunk, as its name implies, the salt-and-pepper grey pattern on this wings blends in perfectly with the varied grey backgrounds of tree trunks. Darwin famously pointed to this moth’s cousin, the European Peppered Moth, as an example of artificial selection: As surfaces turned black under the coal of the first Industrial Revolution, the wings of British peppered moths turned black in order to match their sooty surroundings. More recently and following the clearing of the skies in our post-Industrial Revolution era, Richard Fox of the British Garden Moths Count Project reported that these black British peppered moths have re-evolved to their original peppered appearance.

A couple of days ago, when I try to take a close picture of the Pepper-and-Salt moth on the road, it is startled and vigorously flaps its wings. Underneath its wings, its thorax or abdomen is painted bright pink with white stripes. At best, I can obtain only a blurred picture of the agitated moth with its pink pants. I check my insect guides and find no mention of the pink undergarments.

A Western Yellowjacket wasp (Vespula penslvanica) was also trapped by cold on the road. It can be distinguished from the paper wasps seen on October 9th by their more stout bodies, hairier thoraxes, and their generally more bee-like appearance. This wasp has a red-brown color to its abdominal segments rather than the typical black. It has probably been displaced here by a recent field-clearing project of the Utah Conservation Corps.

This afternoon, there are two more insect refugees on the road. At mile 1.6, the first refugee is a wasp with a dark red-brown head and thorax. The upper one-third of the abdomen is also dark brown, before it turns to alternating yellow-black bands. I am unable to find it in any guides, and this wasp is unidentified. Further down canyon, another wild bee variant is found. The lower third of its abdomen is black, while the upper third is alternating black and red-orange. It is similar too but not the same as the red-rumped central bumble bee, first seen on September 24th. The red-rumped central bumble bee has a red, not a black rump. It could be the Yellow-head bumble bee (Bombus flavifrons), but it is too late in the year for them to be out.

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