City Creek Nature Notes – Salt Lake City

December 17, 2016

December 17th

Filed under: Birds, Colors, Elk, Insects, Light, Pepper-and-salt Moth, Seasons, Unidentified — canopus56 @ 7:51 pm

Late Signs of Coming Winter

5:00 p.m. Another arctic front came through last night, today there was light snow, and temperatures have dropped into the twenties in the city and into the teens in the canyon. For jogging, it is time to start dressing for the coldest part of the year. I start layering up by putting on two warm turtleneck shirts, a wind breaker, and then a sweater. For the lower body I have two socks and a light stretch running pants and a second heavier running pant. With heavy gloves, I am comfortable enough, if moving.

Everything in the canyon is frosted with two or three inches of snow. The Sun is near its most southern position on the ecliptic, and it sets behind the south wall at mile 1.0 and not the north wall. At dusk at milepost 1.5, a warm ray of sunshine breaks through the clouds and casts a warming light the western hills. The ray disappears, but as sunset continues, the cloud that obscures the sun is highlighted at its fringes with bright orange-yellow glow. Through the orange light at the distant canyon mouth, a raptor glides through yellow light. No elk or deer nor their tracks are seen.

5:00 p.m., December 12th, 2016 (Supplement). Winter starts on the 21st. Below Black Mountain, I can see elk tracks that traverse from the Avenues ridgeline down to the canyon road. For me, this is one of the early signals of true winter, which is in five days. The beginning of winter is not first snow, the frost, or even the first real cold spell. It is when the elk collect and migrate out of the higher mountains through Red Butte, Little Mountain Pass, Emigration Canyon, and upper City Creek. Four the next few weeks, they will congregate and file past this mid-elevation of Black Mountain, cross City Creek Canyon, and climb up to winter grazing habitat behind Ensign Peak. Black Mountains’ snow covered lower slope betrays their movements.

At Guardhouse gate, there is small pepper-grey winter moth (probably a Pepper-and-salt moth) that is, for the lack of a better word, panting like a dog. It flutters its wings in a slow sinusoidal rhythm and not in the frenetic flapping before flight. It must be warming its muscles.

In Thoreau’s “Journal” on December 17th 1850, he observes that the practical working length of twilight is lengthened by light reflecting from snow. On December 17th 1853, he finds more moth or butterfly cocoons hanging from trees. On December 17th, 1856, he finds a winter scrub oak forest to be beautiful. On December 17th, 1859, he finds small seeds on the snow surface that have been dispersed by the wind.

On December 17, 1926, the Salt Lake Telegram reported that a mature chestnut tree, that was being dug up at the corner of 100 South and 300 East, was being donated and relocated to Memory Grove Park in City Creek Canyon.


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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