City Creek Nature Notes – Salt Lake City

December 12, 2016

December 12th

Filed under: Meadow Mile 2.1, picnic site 3, picnic site 6, Sounds, Weather — canopus56 @ 7:50 pm

Loud City Rumble

8:00 p.m., December 9th, 2016: After a hectic night and day of work, I am spent. Having aged, I am more aware that I should give myself a full day. My circadian rhythms are disrupted and to help them reset I go for a late night jog. The Moon is three-quarters full and the sky is partly overcast, so there is sufficient light that seeing is not a problem. It is late on a Friday night, it is at the height of shopping season, there is major sports game downtown, and jetliners taking off from the airport are routed over the canyon. To my surprise, city rumble noise (November 18th) is deafening deep into the canyon. I try to outrun it, but even at milepost 2.0, the mechanical noise level is still around 20 decibels. I have never heard it this loud; city rumble usually cuts out within the first one-third of a mile near picnic site 3. Although there is no healing solitude in the canyon tonight, I am rewarded with moonlit silvery shadows cast by myself and the trees. 5:00 p.m., December 11th, 2016: City rumble is still relatively loud. Going down canyon, I first detect it around picnic site 6. 5:00 p.m., December 12th, 2016: The noise of City rumble has retreated to below picnic site 3.

While noise becomes softer; temperatures rise: 8:00 p.m., December 9th. The arctic air pocket has dissipated, and the resulting higher temperatures have changed the snow. It is now partially melted and a shoe into its surface parts with wet compaction. It is what backcountry skiers would call a fast snow: skis glide at a high-speed through the snow, but there is a reduced ability to control turns. Almost all of the pack on the north west side of the canyon has melted away. 5:00 p.m, December 11th: Temperatures remain in the high thirties, and as a result the Gambel’s oaks are drying out and those trees of the half Black Tube (Entry, Dec. 11th) are becoming gray again. Yesterday’s rain has changed the snow. Now it has a crusty surface. A foot breaks through the surface, and the fast snow of yesterday is underneath. Backcountry skiers know this to be a difficult snow. The crust breaks in varying degrees of resistance, and on occasion, will pile up and grab a ski, thus bringing the skier to an immediate stop. 4:30 p.m., December 12th: Jogging up canyon, slopes that face down canyon and the Sun are free of snow. Upon reaching milepost 1.5, I turn around, and find the opposite is true. All of the north up-canyon are still frosted in snow. Snow only remains on the north facing slopes and in the very bottom of the canyon. Further up canyon at Black Mountain, heavy snow still covers the ground and the trees remain frosted.

In Thoreau’s “Journal” on December 12th, 1858, he observes large flocks of red polls, an eastern finch similar to the European house sparrow found in the western states.

September 20, 2016

August 22nd

Filed under: Cliff Swallow, Dragonfly, Insects, Meadow Mile 2.1 — canopus56 @ 11:17 pm

Circling Swallows

7:45 p.m. There is a meadow near mile 2.1. The meadow is in shadow, but about 25 feet above the meadow, the horizontal line of sunset is rising up the south canyon wall. In this sunset light and for a swath about three eighths of a mile long, fifteen swallows are hunting by flying in ellipses. Their orbits appear random, but after about five minutes, curiously, groups of five or ten swallows will meet in a small cluster in the sky. Then they will disperse into their individual ellipses. I watch them repeat this behavior two or three times. How they can time this is a complete mystery. Perhaps there is some explanation in mathematics of non-linear chaos. (For the mathematically inclined, the swallows are flying a pattern suggestive of Lorentz attractor.)

What the swallows are hunting is unclear. In the shadowed meadow, a few dragonflies also circle. Do the dragonflies eat small insects and then do the swallows eat the dragonflies? But there are too few dragonflies to support fifteen hungry swallows.

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