THE EFFECT OF CLIMATE UPON PACIFIC COAST 



BIRDS. 



BY L. BELDING. 



It has been the custom of American ornithologists to refer to the 

 birds of the damp forests on the coasts of Northern California, Ore- 

 gon, Washington, and British Columbia as the "dark, northwest 

 coast birds;" of the birds of the arid treeless areas east of the Cas- 

 cade and Sierra Nevada Mountains, of the Mojave and Colorado 

 deserts and Arizona, as the "bleached desert races;" of the resident 

 peculiar forms of the Sacramento and San Joaquin valleys, as birds 

 of the "dry, hot interior," thus referring to localized forms, which 

 migrate little, if at all, and in the terms quoted, correctly conveying the 

 idea that the environment or climate inhabited by these forms is the 

 cause of their divergence from nearly related species and sub-spe- 

 cies. A familiar axiom carrying the same idea is, "Migration holds 

 species fast, localization lets them slip," the purport of which is that 

 birds which migrate and are subject to many conditions are much 

 less liable to change than those which do not migrate and are subject 

 to few conditions. Whatever potency natural selection or sexual 

 selection may have in causing differentiation — and their operation 

 in this direction seems very obscure — here, where there is such vari- 

 ety of climate, soil, and vegetation, consequent upon difference in 

 altitude and humidity, proximity to the ocean and removal from it, we 

 may well consider climate as our most important factor in evolution. 



Turning from birds to man, we see in our country, descendants of 

 people of various European nationalities who bear the impress of our 

 climate and the distinctive characteristics of Americans. Even the 

 pure-blooded Jew, whose occupations and modes of living vary but 

 little, is similarly affected, and I have noticed that the English Jew 

 resembles, more or less, the Englishman, the German Jew the Ger- 

 man, and I think the Polish Jew is different from any of these. It 

 is difficult to see how selection could have had much influence in 

 modifying the Jew. 



The black man appears to be one of the natural products of Africa, 

 the copper-colored man of America, but I would not venture to pre- 

 dict that the Caucasian and negro of America will in the dim future 

 become copper colored, and that our vexatious race problem will in 

 this way be solved, but I do venture to protest against giving the 

 theory of selection undue prominence. 



