Jeffries on the Ipsivich Sjmrrow. 



105 



month. By December the princeps in their turn move south, a few re- 

 maining through the winter. 



If we regard princeps as merely a Northern form or variety of P. savanna, 

 in what ought we to expect it to differ from the typical form V First, it 

 should be of greater size ; second, it should be of lighter color, but have 

 the same style of coloration. 



First, as to size, princeps is undeniably larger on the average than 

 Savanna Sparrows shot in Massachusetts, but not so decidedly as I had 

 inferred from published measurements. The following table shows that 

 specimens of princeps intergrade with typical savanna in size, while the 

 average size of princeps is smaller than var. sandwichensis as given in 

 " History of North American Birds " : — 



Measurements* 



* All of the specimens of Passeradii^ prinreps were taken either at Marblehead or Swampscott. 

 Four are in Mr. Brewster's collection, and the remaining fifteen in that of Mr. J. A. Jeffries, 

 t Average of eleven specimens. 



Certainly princeps is not distinguishable from savanna by its larger size, 

 since it is generally smaller than that variety which lives in the North- 

 west. In the above table most weight is given to length of wing, that 

 being the measurement least liable to vary with the person measuring. 



Secondly, princeps, the Northern race, should be the lighter. Here we 

 have one of the characteristics given as easily distinguishing princeps from 

 savanna. The plan of coloration is alike in both forms throughout, the 

 variation being simply one of intensity of color. The color of the ventral 

 surface of both birds is often identical. The yellow superciliary stripe 

 varies with season, and in different individuals, sometimes there being no 

 yellow, while again it is very marked. One point in which extreme speci- 

 mens seem to differ is, that savanna has a good deal of buff on the sides 

 of the head, breast, and flanks ; the Avhole back also shows this buffy 

 tinge ; while a light princeps shows very little of it, if any. Intermediate 

 specimens, however, grade one into the other. It so happens that we 

 have an excellent parallel of this coloration in our Thrushes, the Southern 

 form of Tardus swainsoni showing a very similar suffusion on the sides of 



