OREGON JUNCO 1053 



everywhere as we hiked into the foothills, Juncos flew from beneath 

 roadside cuts, from imder shrubs covered and bent ^^•ith snow, and 

 from the path ahead of us. It seemed to us as though the birds were 

 marking time imtil they could continue migration. 



We could easily recognize more than one race. Included in the 

 many small irregular sized flocks, besides our local breeding race 

 w«ar?isi, were other Oregon jimcos -udth darker heads, more bro-wTiish 

 sides, or more bro\Miish backs than mearnsi. Two or three slate-col- 

 ored jimcos were seen this day, too, confu-ming that migratory juncos 

 were indeed present. Two weeks later juncos w^ere gone from the low 

 coimtry and only oiu" local breeding birds were seen in the mountains. 



Migration dates in spring, as given by A. A. Saunders (1912a) for 

 western Montana near Butte, are March 10 to April 5. L. R. Dice 

 (1918), at Prescott in southeastern Washington, for the years 1905 to 

 1913, gives April 13 and May 1 as last spring observations, indicating 

 migration had taken place from the low country. In the Lahontan 

 Valley, Churchill County, Nev., an irrigated farming area, J. R. 

 Alcorn (1946) says: "Jimcos (of all races) were seen frequently each 

 month from September to April, inclusive." The status of the dif- 

 ferent races for California as summarized in Grinnell and Miller (1944) 

 indicates spring migration takes place in March and April. R. B. 

 Rockwell (1908) and others say that the bidk of migration northward 

 in Colorado is about April 1. 



T. T. and Elinor McCabe (1927), at their banding station in inte- 

 rior British Columbia, report that diu-ing the 1927 spring migration 

 "the great rush began on the 10th [of April]." They comment also 

 on the excess of males over females, about four to one. At Coeur 

 d'Alene, Idaho, Henry J. Rust (1915) ^vTites: "Arriving as early as 

 February 22, becoming common by first week in April." A. R. 

 Phillips (1933) says wintering Oregon juncos were seen in the Bab- 

 oquivari Mountains, Ariz., imtil Mar. 16 and Apr. 1, 1932. 



The experiments of Albert Wolfson (1942) with resident and migra- 

 tory races of Oregon junco deserve mention. Wolfson says that 

 internal and external factors were found to regulate the spring migra- 

 tion of the Oregon junco. The external factor is the length of day. 

 "As the days increase in length the birds are awake for longer periods." 

 Longer periods of being awake stimulate an increase in production or 

 release of the production from various glands, which in turn causes 

 physiological changes in the bird such as recrudescence of the gonads 

 and the deposition of large amounts of fat. The internal stimulus 

 triggers the actual migration by releasing the nervous mechanism that 

 controls the migratory behavior. Resident birds show no deposition 

 of fat, says Wolfson. On the other hand, the testes of the residents 



