The Yellow-billed Magpie 



or else the nuttalli stock was planted here by direct, and of course, arti- 

 ficial, though prehistoric, importation from eastern Asia. It is quite 



conceivable that Pica pica stock, 

 jfjg 1 ' especially if represented by a single 



pair, suddenly released under ab- 

 solutely different conditions, 

 should develop a sharp variant 

 which would soon achieve validity 

 as an independent species. Against 

 the former hypothesis should be 

 urged the failure of the species to 

 react from its narrow confines (in 

 theoretical southern California), 

 when it was released by the ice. 

 And in favor of the latter hypo- 

 thesis may be urged the very 

 limited distribution which the bird 

 has attained, even in California. 

 It is authoritatively reported from 

 only thirty counties (or, by in- 

 clusion, thirty-seven), all contigu- 

 ous, out of a possible fifty-nine. 

 We cannot tell; but at any rate 

 there is a profoundly interesting 

 problem here. 



One who is familiar with both 

 species, pica and nuttalli, finds it a 

 little difficult to draw distinctions 

 of any other sort save color and 

 size between them. There are no 

 recognizable peculiarities of voice, 

 or motion, or nesting habit, which will serve to distinguish them. Yet 

 I have a feeling that the Yellow-billed Magpie is a weaker stock, less 

 aggressive and resourceful, than its northern kinsman. On the whole, 

 too, I think it is a quieter bird. Occupying, as it does, a more favored 

 area, with open winters, there is perhaps a less highly developed social 

 instinct in the southern bird, with probably a less frequent resort to 

 mob tactics. But none of these points can be pressed. 



Whatever the cause, whether a less virile stock, or the more intimate 

 pressure of civilization, it is certain that Yellow-billed Magpies are 

 suffering a gradual reduction of distributional area, with steadily de- 

 creasing numbers. At the present rate of destruction (from injuries real 



Taken in San Luis Obispo County Photo by the Author 



A CRITICAL MOMENT— COUNTING THE EGGS 



40 



