202 Recent Literature. [ £& 



RECENT LITERATURE. 



Grinnell's ' The Biota of the San Bernardino Mountains.' ' — During the 

 seasons of 1905, 1906, and 1907, the author devoted considerable time, 

 often aided by several assistants, in investigating the fauna and flora of 

 the San Bernardino Mountains in southern California, which, from their 

 altitude and isolation, offer an attractive field for the study of distribution. 

 The present report of his researches includes a consideration of the life 

 zones of the region; descriptions of the localities visited, with special 

 reference to the faunal complexion of each ; a discussion of the bird popula- 

 tion and the influences modifying it; a list of the important species of 

 plants, with notes on their distribution; a list of the birds of the region 

 (139 species), with a detailed record of the distribution of each, with bio- 

 graphical and critical notes on many of them; and similar lists of the 

 mammals and reptiles. 



The San Bernardino region rises from a base level, on the south side, of 

 from 1500 to 2500 feet, and on the north side of about 4000 feet, to the 

 maxima of 10,600 (San Bernardino Peak) and 11,485 feet (San Gorgonio 

 Peak), and thus includes the life zones from the Lower Sonoran to the 

 Alpine-Arctic. The limits of these several zones are discussed, with lists 

 of the plants that characterize them. 



Under the caption 'Bird Population and its Modifying Influences/ the 

 food supply is considered to be the factor that determines the maximum 

 number of birds that can exist in a given region. "Competitive struggle 

 between species has led to the adoption of remote and otherwise unex- 

 plainable habitats, temporary or constant. It has also led to the develop- 

 ment of various and perfected means of food-getting." In this connection 

 attention is called to the "almost universal exodus in July," from the 

 coastal lowlands of southern California, " of many of the birds of the 'sum- 

 mer-visitant' category which have bred and raised broods during April, 

 May and June." A considerable number of species (which he enumerates) 

 "become scarce, or disappear altogether towards the end of July. . . .when 

 everything becomes excessively dry; among plants most annuals have 

 died, and the perennials have ceased active growth; insects become rela- 

 tively rare, except along watercourses. The May bird population, which is 

 abundant, cannot continue to be supported after this 'winter' [dry] season 

 sets in, and the result is, they must move elsewhere." He has found that 

 they then move up to the mountains, in families of young and old, where 

 the climate is moister, where vegetation still flourishes, and where insects 

 are abundant. 



"All this invasion of the higher altitudes occurs when spring and summer 



1 The Biota of the San Bernardino Mountains. By Joseph Grinnell. University 

 of California Publications in Zoology, Vol. V, No. 1, pp. 1-170, pll. i-xxiv. Decem- 

 ber 31, 1908. 



