City Creek Nature Notes – Salt Lake City

January 16, 2017

January 14th

Filed under: Blacked-Headed Chickadee, Sounds — canopus56 @ 1:31 am

Chickadee Call

2:00 p.m. I am greeted beyond Guardhouse gate with the high-pitched sound of another inquisitive Black-capped chickadee. I have also begun measuring the decibel sound levels increased by urban noise in the canyon using cell phone software. At Guardhouse Gate with urban noise, or city rumble (Nov. 18th, Nov. 25th, Dec. 12th), the background sound level is around 62 decibels, and that sound consists mostly of urban noise. In response to this urban noise, recent research suggests that the call of chickadees may be increasing in pitch and increasing in frequency.

The adaptive acoustic hypothesis suggests that evolutionary pressure from habitat molds the pitch and duration of bird calls (Boncoraglio and Saino). Open meadows such as on Antelope Island in the Great Salt Lake would favor birds with high pitched calls like the meadow lark. In open meadow sounds are not attenuated by forest leaves, and the high-frequency high-energy sounds travel further. Using a tone generator, I estimate the the highest pitch of the chickadee’s call around 3khz, near the high end of frequency of normal human conversation. In deciduous forests, leaves absorb sound energy and reverberate and scatter higher pitched calls, so lower frequency sounds travel farther. Pine needle forests have an intermediate affect on sound attenuation. Thus, in wooded forests, like the canyon, resident owls use lower pitched calls. A behavioral variant of the adaptive acoustic hypothesis is the noise-dependent frequency hypothesis (Proppe et al). Under the noise-dependent frequency hypothesis, birds will increase the frequency of their pitch to overcome the masking effect of urban noise and to maintain intelligible communication. In 2012, Proppe and colleagues at the University of Alberta found that Black-capped chickadees sang at higher frequencies in both noise-polluted open meadow and closed forest environments as compared to similar quiet environments. In 2013, Goodwin and Podos at the University of Massachusetts at Amherst found that Black-capped chickadees in response to artificial masking tones decreased average time between calls by about thirty seconds. Both of these changes in calls compensated for impaired communication in higher noise polluted environments.

In Thoreau’s “Journal” on January 14th, 1852, he again notes blue shadows in winter snow. On January 14th, 1857, he finds many caterpillar cocoons on trees overhanging a stream. On January 14, 1860, he comments on the pure blue color of the sky on a clear winter day.

On January 14, 1914, the City Commission recommended issuance of a major bond to finance water system improvement recommended by the Commercial Club, including building two dams in Big Cottonwood and a 5,000,000 gallon distribution reservoir tank in City Creek Canyon (Salt Lake Tribune). On January 14, 1913, Superintendent of Waterworks C. F. Barrett presented a plan to the City Commission along the lines of the Commercial Club proposal, including building two dams in Big Cottonwood but only tunneling in City Creek to develop springs (Salt Lake Tribune). Barrett proposed the formation of a canyon watershed patrol to police all watershed canyons, including City Creek, for water quality violators (id.) With respect to a proposal to develop of highway up City Creek to Morgan County, Barrett stated, that

I respectfully submit that progressive policy on sanitary matters would contemplate bringing the other canyons up to the standard of City creek at present rather than reducing this [City Creek] canyon to the poorer condition of the others, and I respectfully recommend that nothing be left undone to defeat any project which would in any way endanger the waters of this stream by any contaminating element (id).

Miners in Hardscrabble Canyon (on the Morgan County side of City Creek headwaters) and Morgan County diary farmers had long argued for construction of a highway down City Creek. With such a road, they would not have to travel the forty mile route over Parley’s Canyon to deliver ore and goods to market.


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