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Migration of the Pinyon Jay in Colorado

Junius Henderson
Publication Information
1 (January-February)
From Field and Study

Migrations of the Pinyon Jay in Colorado

The Pinyon Jay (Cyanocephalus Cyanocephalus) is an erratic bird in Boulder County and other portions of Colorado beyond the range of the pinyon pines, “continually changing location according to food supply” (Cooke). Betts says they have been seen in Boulder County every month of the year except December. For several years, in May, especially late in the month, they have been seen flying over Boulder daily in large flocks, almost always moving a little west of north. This has been so regular as to indicate a normal spring migration, such as occurs in Wyoming, according to Knight. I have also seen them in October and November at Boulder, flying in various directions, but mostly south. The puzzling autumnal movement of these jays at Boulder in 1919 has attracted the attention of many persons who ordinarily do not notice the birds very closely. Beginning about August 25 they were seen daily flying over in scattered groups and small flocks, passing so continuously sometimes in the mornings that for an hour or two their harsh calls could be heard almost without cessation, and less continuously later in the day. Up to October 8 many thousands passed, almost without exception flying about ten degrees north of east, from the mountains out over the plains, at right angle with the spring flight. I saw them but once flying in any other direction, and that was the last flock seen, about fifty birds, on October 8, flying in exactly the opposite direction. All observers here report about the same experience. Mr. Geo. E. Osterhout, of Windsor, northeast of Boulder, wrote on October 6 that he had seen no Pinyon Jays there this season. Professor L. A. Adams, of Teachers College, Greeley, wrote on September 23 that he had seen none until September 16, two days after my letter reached him, when they first appeared and had been flying over almost every day since in large flocks, travelling east. In another sentence he says “always going or coming from the west to east or vice versa.” Mr. W. L. Burnett, of the State Agricultural College, Fort Collins, wrote on September 20 that he had not seen or heard any of the jays there this season. I should like to know whether other observers have noted their movements east of the Rockies in Colorado, Wyoming or adjacent States.

Junius Henderson

Boulder, Colorado, November 10, 1919

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