The nature of the restriction in each case is more or less obscure: sometimes, as with the strong wind, it is evidently some direct influence of the environment upon the birds. This particular kind of magpie appears not to extend its range into lands where there is frequent high wind, long, snowy, and cold winters, or especially dry and hot summers. Another is open ground either bare, as in well-kept orchards, or comprising cultivated fields or grassy pastures and slopes. The whole question of relationships and trends of variation in the magpies is an attractive one for the person who may be able to collect the pertinent evidence.Ī feature common to situations inhabited by the yellow-billed magpie is the presence of tall trees, usually in linear arrangement bordering streams or in parklike groves, either on valley floors or on hills. The anatomical, behavioral, and geographical situations there are much like the ones encountered in California.
Somewhat similar problems arise in determining the phylogenetic status of the magpies in southwestern Europe and northern Africa. It is true that the birds in western Europe appear structurally to he much like the Amer~-an black-billed ones, although these two kinds are separated by several forms that differ considerably from them. The relationship indicated there seems even more remote than that with the yellow-billed bird, but it is commonly recognized as a subspecific one.
The situation is not much different on the opposite side of the range of the black-billed bird, where it approaches the nearest representative of the group in Asia. The ranges do not overlap in fact, the gap separating them is about 50 miles wide at its narrowest place. Some differences in habits also may be seen on close study of the two birds.
MAGPIE SACRAMENTO TWOBIRD SKIN
The most nearly obvious distinctions have to do with the possession of the yellow pigment, which shows in the bill, claws, and some places in the skin of the yellow-billed form, and its generally smaller size. Probably it makes little difference which way we think of them so long as we recognize the nature of the characters and ranges of the birds, insofar as they represent the true relationship, for it is scarcely possible to prove the correctness of either opinion. Some persons like to think of this relationship as subspecific others consider the two kinds as distinct species. The yellow-billed magpie is obviously a close relative of the blackbilled magpie. The area occupied is less than 150 miles wide and extends for about 500 miles from north to south. They are restricted to that part of the State west of the Sierra Nevada from Shasta County, at the north end of the Sacramento Valley, southward to Ventura and Kern Counties, and are chiefly in the Sacramento and San Joaquin Valleys and the coastal valleys south of San Francisco. Localities occupied are known with exhaustive detail. California contains within its borders the whole range of the yellowbilled magpie.
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