City Creek Nature Notes – Salt Lake City

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).

February 20, 2017

February 20th

Filed under: Bald-Faced Hornets, Blacked-Headed Chickadee, picnic site 4, Wasp — canopus56 @ 1:57 pm

Hornet Nest

Opened Hornet Nest

External Link to Image

Source: Author. The nest is rotated 180 degrees and in nature points down.

10:30 a.m. It is a very windy day, and a holiday. The wind blows leaves on and by the side of the road in two patterns. First, is a widening v-shaped spray. Second, the brown leaves dance together in a circle and are driven by a hidden dust devil. The canyon is again full of strollers, runners and bicyclists. The Black-billed magpies have come around the ridgeline from Ensign Peak (Feb. 15th), and taken up residence near picnic site 2 and down canyon from the Black-capped chickadees.

Near picnic site 4, I peel back the bark of a horizontal fallen snag. Underneath the bark are no insects, but there are long strands of a fungus sticking between the trunk and the bark. Hidden well up under the bark is a Paper wasp nest. The wasps carefully choose this place. Only a small opening in the bark leads down a tunnel to their hidden fan shaped nest. This is the natural version of their human adapted nests at the Red Bridge and in the natural gas pipeline valve station tubes (Dec. 10th). At those sites, the Paper wasp nests are inside metal fence hangers and bridge tubing. At picnic site 9, the hornet’s nest that I discovered on September 27th, long abandoned, has finally fallen from its tree. Inspecting the nest, it is apparent how the Bald-Faced hornets, who are a more social form of wasps, have engineered an evolutionary improvement in home building over their cousins, the Paper wasps. The Bald-Faced hornet nest also contains fanned shaped crèches that hang down from an attachment point. But in the hornet nest, they have constructed apartment style tiers. From the middle of the first, largest tier, a stack protrudes and on the bottom of that stalk, a second tier hangs. The third smallest tier hangs below. The diameter of the respective tiers contain 17, 12, and 9 cells, and this suggests that this compact eight inch high colony contained about 380 individuals. It is around this that the hornets build a thin multi-layer shell about two to three times the central colony. The shell contains air gaps that provide ventilation and natural cooling. The nest’s core colony is a marvel of insect engineering and the broken outer paper shell an artistic swirl of gray toned bands. That such beautiful complex construction can arise from simple, almost robotic insects is inspiring.

On my way down-canyon, I check the five hornet nests that I inventoried on December 10th. Winter weather has blown all from the trees. In a few months, will they will rebuild at the same locations?

In Thoreau’s “Journal” on February 20th, 1856, he finds otter tracks.

On February 20th, 1909, City Engineer Louis C. Kelsey reported on infrastructure accomplishments across several years of his tenure (Salt Lake Tribune, Salt Lake Herald). He recommended the replacement of the wooden flume below the City Creek Brick Tanks reservoir be replaced with a concrete flume and that water mains be extended into the business district.

September 28, 2016

September 28th

Filed under: Insects, Meadow Mile 1.3, People, Places, Pleasant Valley, Sunflower, Uncategorized, Wasp — canopus56 @ 8:00 pm

Iridescent Wasps

2:00 p.m. The last of the sunflowers in Pleasant Valley are giving out, and a just a few remain at the natural gas check-value in Pleasant Valley at mile 1.3 across from picnic site 11. I check them for pollinators. One is surrounded by a swarm of about 10 micro wasps. They are less than one-quarter of an inch long and are steely dark blue green. Their thoraxes and heads are iridescent, and their wings are brown-black. They are definitely not flys, as they have discernible stingers. They are not the same micro-wasps seen back on August 9th. Those had yellow banding on their thoraxes while these are completely black. I am unable to identify these wasps, nor have I seen them before in the canyon.

In the canyon on this warm fall afternoon, there are two groups, lead by graduate teaching assistants, of university biology seniors studying plant systematics (University of Utah BIO 5435). They carefully go through each plant along the roadside and discuss its scientific name. These are the real current and future experts on classifying life in the canyon.

Late in the evening, another storm front moves in, and a cold rain falls.

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