City Creek Nature Notes – Salt Lake City

October 6, 2016

October 6th

Battling Birds

10:45 a.m. A flock of Western Scrub Jays (Aphelocoma californica) have returned to the canyon, as revealed by their raucous screech call. On the north embankment of the road near Guardhouse Gate, one jay lands, picks up an acorn off the slope, throws it into the air above its head, and then expertly catches and swallows the falling nut. Like the flickers, the Gambel’s Oak acron are the scrub jay’s staple during the non-breeding season. Scrub Jays are one of the two prominent jays that pass through the canyon; the other is Stellar’s Jay (Cyanocitta stelleri). Both the western jay, Stellar’s Jay, and magpies are cousins in the family Corvidae.

Just northeast of Guardhouse Gate, the flock of Scrub Jays and the flock of Northern Flickers are having a heated discussion. Given that the Scrub Jays the more aggressive species, I suspect that they will get the best of the matter.

At mile 1.7 near the eastern end of Pleasant Valley, the Black-billed magpies (Pica hudsonia) have also returned. The Black-billed magpie is a commonly-seen over-wintering bird in urban Salt Lake City, and they are known for their obnoxious “wenk-wenk-wenk” screech. They are well-adapted both the city and their native open chaparral. Magpies are another bird for which I have a great deal of respect. They are highly intelligent and opportunistic. One winter, after leaving a window open, I discovered two them in the kitchen snacking on granola and three others exploring the house. They over-winter in Utah and seem to be impervious to sub-freezing temperatures that would kill a human within an hour, and despite being carrion eaters, they find adequate food during the winter. They are fearless of humans. Today, as I jog pass the mile 1.5, a magpie is sitting at the base of the 1.5 milepost sign with his back to the road. He or she only gives me a brief acknowledging glance as I stride by.

The meadow at mile 1.7 is a recuperating, open, and circular flat where a concrete reservoir used to sit. During the 2000s, the reservoir was decommissioned, like many older dams on the western urban slopes along the Wasatch Front range, out of concern that water retention structures would fail in a large earthquake. Trees circle the outside of the flat.

Today, a magpie flock is stretched along several trees on the far edge of the flat, and on the side nearest the road, a similar flock of Scrub Jays rest in a string of trees. At the tree dividing the two sides, a couple of magpies and jays are debating loudly. The magpies are larger than the jays, and they are more of a bully than their cousins. I suspect the magpies will win the discussion.

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