112 Univers^ity of California Publications in Zoology [Vol. 21 



The figures given for the southern half of the Sierra Nevada and 

 for the Sierra foothill sections are based in part on material secured 

 by expeditions from the California Museum of Vertebrate Zoology into 

 the Yosemite region, covering every month of the year. The results 

 apply only to this limited area, but judging from these figures the 

 subspecies of the Schistacea group form but a small part of the winter 

 population of the Sierra Nevada. 



I am convinced that there is significance in the results of these 

 tabulations. I believe them to indicate that some forms really have 

 a winter habitat nearly as sharply defined as the summer home, while 

 others show preferences somewhat less marked. 



One lesson to be learned from this analysis of winter collections 

 is that inasmuch as the extensive collecting of specimens at certain 

 limited spots has yielded definite knowledge of a sort that obviously 

 could not have been obtained in any other way, similarly extensive 

 collecting at places regarding which we are still very ignorant as to 

 the winter avifauna, may be expected to explain many details of 

 distribution in this group of birds of which at present we have no 

 knowledge. In the writer's opinion, the solution of such complicated 

 questions of relationship and distribution as are presented in the 

 Passerella group lies only in the wholesale but intelligentlj^ directed 

 collecting of specimens. 



In the course of the writer's field experience he has from time to 

 time noted facts in the distribution and migration of fox sparrows, 

 which, disconnected though they be, are set down here as having some 

 bearing on the subject in general. In a number of years of observa- 

 tion about Los Angeles, fox sparrows were found to be extremely rare 

 in the flat valley in which the city is situated, one or two of the 

 Unalaschcensis group, and two altivagans being all that were noted, 

 and these at long intervals. In the low foothills of the Santa Monica 

 Mountains, but a few miles away, certain subspecies could be found 

 in fair numbers regularly every winter. This was also the case in 

 the brush of the Arroyo Seco, a stream issuing from the mountains 

 near Pasadena, fox sparrows being seen regularly in winter in the 

 bordering willow thickets, practically as far as the junction of this 

 stream with the Los Angeles River, at the edge of the city. 



In years past many southern California valleys were covered with 

 miles of more or less dense chaparral. Much of this land has been 

 cleared for agricultural purposes, but some fairly extensive areas of 

 this nature still remain, the haunts of many typical Californian animal 



