I 29 settlers— old and new 



Forest Service to reduce erosion along the desert washes, 

 are native to the same Mediterranean region to v^hich Cal- 

 ifornia has sent its palms. Smyrna figs grow well in Cali- 

 fornia but, as I have said before, wouldn't fruit until it 

 was discovered that they had to have a certain wasp which 

 not only had to be imported to please them, but which it- 

 self had to be given an otherwise useless scrub fig from the 

 Near East upon which it depends during a part of its life 

 cycle. 



In a region of deserts broken up by mountains as our 

 southwestern deserts are, such mountain or desert barriers 

 are very important factors in controlling the distribution 

 of animals as well as of plants, and "islands" of the one or 

 the other are isolated long enough to begin to develop in- 

 digenous species very much as the isolated Galapagos Is- 

 lands produced those which first puzzled and then en- 

 lightened Darwin. The best known case is that of the 

 abert squirrel and the kaibab squirrel. 



The first I see often at seven or eight thousand feet on 

 the nearest mountain range. With the possible exception 

 of the Sonoran fox squirrel, whom I have been lucky 

 enough to glimpse within the few square miles where Ari- 

 zona, New Mexico, and Old Mexico meet and where 

 alone he consents to cross the border from Mexico, the 

 abert is the handsomest squirrel I know: conspicuously 

 larger than the familiar gray, brown-backed with an al- 

 most red saddle, with pointed ears emphasized by pointed 

 tufts of hair, and with an exuberant tail part gray, part 

 white. He is a mountain creature inhabiting a rather re- 

 stricted area and south of the Grand Canyon he is just 



