RECENT LITERATURE 
99 
Douglas ground squirrel. Apparently differences in color separating this squirrel 
from others in California are associated with differences in habitat and food 
preference as well (p. 53). It is unfortunate that there are those who question 
the value of systematic work, description, and classification. As the eminent 
English mammalogist Hinton says, . . so many have yet to learn that all 
branches of science are valuable and interdependent, that in reality there are not 
two kinds of science — one called ‘applied,’ essential, it extracts gold; the other 
called ‘pure,’ quite unimportant it extracts nothing but facts.” (M. A. C. Hinton, 
Rats and mice as enemies of mankind, British Museum of Natural History, 
London, 1918, pp. 26-27.) 
Further on in the account of the Douglas squirrel the principle is enunciated 
that “the squirrels require a certain amount of space around them so that they 
can have a fair show of reaching the safety of their burrows after an enemy is 
first caught sight of” (p. 54). This principle is apparently of general application 
among the Sciuridse. 
While in the past, hibernation of animals as a result of the effect of cold and 
snow has been emphasized, estivation due to a lack of moisture has hardly received 
its share of attention. Recent investigations have demonstrated its importance. 
Thus Grinnell and Dixon show that the. Oregon ground squirrel of the warm 
Upper Sonoran and Transition zones of northern California disappears from 
view during July and does not reappear until the following March (pp. 66-67). 
On the other hand the Belding ground squirrel {Citellus heldingi) of the cold 
Hudsonian Zone of the high Sierra Nevada does not become quiescent until a 
full two months later than the Oregon ground squirrel (p. 72). 
The immensity of losses to agriculture caused by squirrel pests is seldom 
fully appreciated. The authors’ studies of Citellus oregonus lead them to conclude 
that 30 grams of forage are eaten daily by each individual. In thickly settled 
squirrel country the average number of the animals per square mile is estimated 
at 70,000, This number will consume 2,100,000 grams, or more than 2 tons of 
green forage per square mile every day. “Granted that a grazing steer eats 
50 pounds of pasture forage each day, we conclude that the squirrels on a square 
mile of pasture appropriate each day the forage which might support ninety 
head of cattle” (p. 63). 
W. T. Shaw’s paper on the Columbian ground squirrel (pp. 118-128) is worthy 
of more than casual attention. This contribution, based on years of work by 
the author, is all too short, and impels the reader to look with keen anticipation 
to the publication of the full report of Professor Shaw’s illuminating investiga- 
tions. These ground squirrel papers of Grinnell and Dixon and of Shaw are of a 
type of zoological investigation which has been all too rare in mammalogy, 
particularly in this country. 
Much credit is due to the State leaders of rodent control in California for the 
enlightened manner in which they are dealing with their problems. If those in 
charge of practical projects of rodent control and animal administration generally 
made as vigorous efforts to stimulate scientific research of a basic character 
and then to utilize the results thereof, there is no doubt whatever that greater 
progress would be achieved than is now the case. 
— Walter P. Taylor. 
